Active Record objects don‘t specify their attributes directly, but rather infer them from the table definition with which they‘re linked. Adding, removing, and changing attributes and their type is done directly in the database. Any change is instantly reflected in the Active Record objects. The mapping that binds a given Active Record class to a certain database table will happen automatically in most common cases, but can be overwritten for the uncommon ones.
See the mapping rules in table_name and the full example in files/README.html for more insight.
Creation
Active Records accept constructor parameters either in a hash or as a block. The hash method is especially useful when you‘re receiving the data from somewhere else, like an HTTP request. It works like this:
user = User.new(:name => "David", :occupation => "Code Artist") user.name # => "David"
You can also use block initialization:
user = User.new do |u| u.name = "David" u.occupation = "Code Artist" end
And of course you can just create a bare object and specify the attributes after the fact:
user = User.new user.name = "David" user.occupation = "Code Artist"
Conditions
Conditions can either be specified as a string, array, or hash representing the WHERE-part of an SQL statement. The array form is to be used when the condition input is tainted and requires sanitization. The string form can be used for statements that don‘t involve tainted data. The hash form works much like the array form, except only equality and range is possible. Examples:
class User < ActiveRecord::Base def self.authenticate_unsafely(user_name, password) find(:first, :conditions => "user_name = '#{user_name}' AND password = '#{password}'") end def self.authenticate_safely(user_name, password) find(:first, :conditions => [ "user_name = ? AND password = ?", user_name, password ]) end def self.authenticate_safely_simply(user_name, password) find(:first, :conditions => { :user_name => user_name, :password => password }) end end
The authenticate_unsafely method inserts the parameters directly into the query and is thus susceptible to SQL-injection attacks if the user_name and password parameters come directly from an HTTP request. The authenticate_safely and authenticate_safely_simply both will sanitize the user_name and password before inserting them in the query, which will ensure that an attacker can‘t escape the query and fake the login (or worse).
When using multiple parameters in the conditions, it can easily become hard to read exactly what the fourth or fifth question mark is supposed to represent. In those cases, you can resort to named bind variables instead. That‘s done by replacing the question marks with symbols and supplying a hash with values for the matching symbol keys:
Company.find(:first, :conditions => [ "id = :id AND name = :name AND division = :division AND created_at > :accounting_date", { :id => 3, :name => "37signals", :division => "First", :accounting_date => '2005-01-01' } ])
Similarly, a simple hash without a statement will generate conditions based on equality with the SQL AND operator. For instance:
Student.find(:all, :conditions => { :first_name => "Harvey", :status => 1 }) Student.find(:all, :conditions => params[:student])
A range may be used in the hash to use the SQL BETWEEN operator:
Student.find(:all, :conditions => { :grade => 9..12 })
An array may be used in the hash to use the SQL IN operator:
Student.find(:all, :conditions => { :grade => [9,11,12] })
Overwriting default accessors
All column values are automatically available through basic accessors on the Active Record object, but sometimes you want to specialize this behavior. This can be done by overwriting the default accessors (using the same name as the attribute) and calling read_attribute(attr_name) and write_attribute(attr_name, value) to actually change things. Example:
class Song < ActiveRecord::Base # Uses an integer of seconds to hold the length of the song def length=(minutes) write_attribute(:length, minutes.to_i * 60) end def length read_attribute(:length) / 60 end end
You can alternatively use self[:attribute]=(value) and self[:attribute] instead of write_attribute(:attribute, value) and read_attribute(:attribute) as a shorter form.
Attribute query methods
In addition to the basic accessors, query methods are also automatically available on the Active Record object. Query methods allow you to test whether an attribute value is present.
For example, an Active Record User with the name attribute has a name? method that you can call to determine whether the user has a name:
user = User.new(:name => "David") user.name? # => true anonymous = User.new(:name => "") anonymous.name? # => false
Accessing attributes before they have been typecasted
Sometimes you want to be able to read the raw attribute data without having the column-determined typecast run its course first. That can be done by using the <attribute>_before_type_cast accessors that all attributes have. For example, if your Account model has a balance attribute, you can call account.balance_before_type_cast or account.id_before_type_cast.
This is especially useful in validation situations where the user might supply a string for an integer field and you want to display the original string back in an error message. Accessing the attribute normally would typecast the string to 0, which isn‘t what you want.
Dynamic attribute-based finders
Dynamic attribute-based finders are a cleaner way of getting (and/or creating) objects by simple queries without turning to SQL. They work by appending the name of an attribute to find_by_, find_last_by_, or find_all_by_, so you get finders like Person.find_by_user_name, Person.find_all_by_last_name, and Payment.find_by_transaction_id. So instead of writing Person.find(:first, :conditions => ["user_name = ?", user_name]), you just do Person.find_by_user_name(user_name). And instead of writing Person.find(:all, :conditions => ["last_name = ?", last_name]), you just do Person.find_all_by_last_name(last_name).
It‘s also possible to use multiple attributes in the same find by separating them with "and", so you get finders like Person.find_by_user_name_and_password or even Payment.find_by_purchaser_and_state_and_country. So instead of writing Person.find(:first, :conditions => ["user_name = ? AND password = ?", user_name, password]), you just do Person.find_by_user_name_and_password(user_name, password).
It‘s even possible to use all the additional parameters to find. For example, the full interface for Payment.find_all_by_amount is actually Payment.find_all_by_amount(amount, options). And the full interface to Person.find_by_user_name is actually Person.find_by_user_name(user_name, options). So you could call Payment.find_all_by_amount(50, :order => "created_on"). Also you may call Payment.find_last_by_amount(amount, options) returning the last record matching that amount and options.
The same dynamic finder style can be used to create the object if it doesn‘t already exist. This dynamic finder is called with find_or_create_by_ and will return the object if it already exists and otherwise creates it, then returns it. Protected attributes won‘t be set unless they are given in a block. For example:
# No 'Summer' tag exists Tag.find_or_create_by_name("Summer") # equal to Tag.create(:name => "Summer") # Now the 'Summer' tag does exist Tag.find_or_create_by_name("Summer") # equal to Tag.find_by_name("Summer") # Now 'Bob' exist and is an 'admin' User.find_or_create_by_name('Bob', :age => 40) { |u| u.admin = true }
Use the find_or_initialize_by_ finder if you want to return a new record without saving it first. Protected attributes won‘t be set unless they are given in a block. For example:
# No 'Winter' tag exists winter = Tag.find_or_initialize_by_name("Winter") winter.new_record? # true
To find by a subset of the attributes to be used for instantiating a new object, pass a hash instead of a list of parameters. For example:
Tag.find_or_create_by_name(:name => "rails", :creator => current_user)
That will either find an existing tag named "rails", or create a new one while setting the user that created it.
Saving arrays, hashes, and other non-mappable objects in text columns
Active Record can serialize any object in text columns using YAML. To do so, you must specify this with a call to the class method serialize. This makes it possible to store arrays, hashes, and other non-mappable objects without doing any additional work. Example:
class User < ActiveRecord::Base serialize :preferences end user = User.create(:preferences => { "background" => "black", "display" => large }) User.find(user.id).preferences # => { "background" => "black", "display" => large }
You can also specify a class option as the second parameter that‘ll raise an exception if a serialized object is retrieved as a descendant of a class not in the hierarchy. Example:
class User < ActiveRecord::Base serialize :preferences, Hash end user = User.create(:preferences => %w( one two three )) User.find(user.id).preferences # raises SerializationTypeMismatch
Single table inheritance
Active Record allows inheritance by storing the name of the class in a column that by default is named "type" (can be changed by overwriting Base.inheritance_column). This means that an inheritance looking like this:
class Company < ActiveRecord::Base; end class Firm < Company; end class Client < Company; end class PriorityClient < Client; end
When you do Firm.create(:name => "37signals"), this record will be saved in the companies table with type = "Firm". You can then fetch this row again using Company.find(:first, "name = ‘37signals’") and it will return a Firm object.
If you don‘t have a type column defined in your table, single-table inheritance won‘t be triggered. In that case, it‘ll work just like normal subclasses with no special magic for differentiating between them or reloading the right type with find.
Note, all the attributes for all the cases are kept in the same table. Read more: www.martinfowler.com/eaaCatalog/singleTableInheritance.html
Connection to multiple databases in different models
Connections are usually created through ActiveRecord::Base.establish_connection and retrieved by ActiveRecord::Base.connection. All classes inheriting from ActiveRecord::Base will use this connection. But you can also set a class-specific connection. For example, if Course is an ActiveRecord::Base, but resides in a different database, you can just say Course.establish_connection and Course and all of its subclasses will use this connection instead.
This feature is implemented by keeping a connection pool in ActiveRecord::Base that is a Hash indexed by the class. If a connection is requested, the retrieve_connection method will go up the class-hierarchy until a connection is found in the connection pool.
Exceptions
- ActiveRecordError - Generic error class and superclass of all other errors raised by Active Record.
- AdapterNotSpecified - The configuration hash used in establish_connection didn‘t include an :adapter key.
- AdapterNotFound - The :adapter key used in establish_connection specified a non-existent adapter (or a bad spelling of an existing one).
- AssociationTypeMismatch - The object assigned to the association wasn‘t of the type specified in the association definition.
- SerializationTypeMismatch - The serialized object wasn‘t of the class specified as the second parameter.
- ConnectionNotEstablished+ - No connection has been established. Use establish_connection before querying.
- RecordNotFound - No record responded to the find method. Either the row with the given ID doesn‘t exist or the row didn‘t meet the additional restrictions. Some find calls do not raise this exception to signal nothing was found, please check its documentation for further details.
- StatementInvalid - The database server rejected the SQL statement. The precise error is added in the message.
- MultiparameterAssignmentErrors - Collection of errors that occurred during a mass assignment using the attributes= method. The errors property of this exception contains an array of AttributeAssignmentError objects that should be inspected to determine which attributes triggered the errors.
- AttributeAssignmentError - An error occurred while doing a mass assignment through the attributes= method. You can inspect the attribute property of the exception object to determine which attribute triggered the error.
Note: The attributes listed are class-level attributes (accessible from both the class and instance level). So it‘s possible to assign a logger to the class through Base.logger= which will then be used by all instances in the current object space.
- ==
- ===
- []
- []=
- abstract_class?
- aggregate_mapping
- all
- allow_concurrency
- allow_concurrency=
- attr_accessible
- attr_protected
- attr_readonly
- attribute_for_inspect
- attribute_names
- attribute_present?
- attributes
- attributes=
- attributes_before_type_cast
- base_class
- becomes
- benchmark
- cache_key
- class_of_active_record_descendant
- clone
- column_for_attribute
- column_names
- columns
- columns_hash
- compute_type
- connected?
- connection
- connection
- connection_pool
- content_columns
- count_by_sql
- create
- decrement
- decrement!
- decrement_counter
- default_scope
- delete
- delete
- delete_all
- descends_from_active_record?
- destroy
- destroy
- destroy_all
- destroyed?
- eql?
- establish_connection
- exists?
- expand_hash_conditions_for_aggregates
- find
- find_by_sql
- first
- freeze
- frozen?
- has_attribute?
- hash
- human_attribute_name
- human_name
- id
- id=
- increment
- increment!
- increment_counter
- inheritance_column
- inspect
- inspect
- last
- merge_conditions
- new
- new_record?
- primary_key
- readonly!
- readonly?
- readonly_attributes
- reload
- remove_connection
- reset_column_information
- reset_counters
- respond_to?
- retrieve_connection
- sanitize_sql_array
- sanitize_sql_for_assignment
- sanitize_sql_for_conditions
- sanitize_sql_hash_for_assignment
- sanitize_sql_hash_for_conditions
- save
- save!
- serialize
- serialized_attributes
- set_inheritance_column
- set_primary_key
- set_sequence_name
- set_table_name
- silence
- sti_name
- table_exists?
- table_name
- to_param
- toggle
- toggle!
- update
- update_all
- update_attribute
- update_attributes
- update_attributes!
- update_counters
- verification_timeout
- verification_timeout=
- with_exclusive_scope
- with_scope
VALID_FIND_OPTIONS | = | [ :conditions, :include, :joins, :limit, :offset, :order, :select, :readonly, :group, :having, :from, :lock ] |
[RW] | abstract_class | Set this to true if this is an abstract class (see abstract_class?). |
Overwrite the default class equality method to provide support for association proxies.
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# File activerecord/lib/active_record/base.rb, line 1489 1489: def ===(object) 1490: object.is_a?(self) 1491: end
Returns whether this class is a base AR class. If A is a base class and B descends from A, then B.base_class will return B.
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# File activerecord/lib/active_record/base.rb, line 1505 1505: def abstract_class? 1506: defined?(@abstract_class) && @abstract_class == true 1507: end
This is an alias for find(:all). You can pass in all the same arguments to this method as you can to find(:all)
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# File activerecord/lib/active_record/base.rb, line 638 638: def all(*args) 639: find(:all, *args) 640: end
Deprecated and no longer has any effect.
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# File activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 92 92: def allow_concurrency 93: ActiveSupport::Deprecation.warn("ActiveRecord::Base.allow_concurrency has been deprecated and no longer has any effect. Please remove all references to allow_concurrency.") 94: end
Deprecated and no longer has any effect.
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# File activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 97 97: def allow_concurrency=(flag) 98: ActiveSupport::Deprecation.warn("ActiveRecord::Base.allow_concurrency= has been deprecated and no longer has any effect. Please remove all references to allow_concurrency=.") 99: end
Specifies a white list of model attributes that can be set via mass-assignment, such as new(attributes), update_attributes(attributes), or attributes=(attributes)
This is the opposite of the attr_protected macro: Mass-assignment will only set attributes in this list, to assign to the rest of attributes you can use direct writer methods. This is meant to protect sensitive attributes from being overwritten by malicious users tampering with URLs or forms. If you‘d rather start from an all-open default and restrict attributes as needed, have a look at attr_protected.
class Customer < ActiveRecord::Base attr_accessible :name, :nickname end customer = Customer.new(:name => "David", :nickname => "Dave", :credit_rating => "Excellent") customer.credit_rating # => nil customer.attributes = { :name => "Jolly fellow", :credit_rating => "Superb" } customer.credit_rating # => nil customer.credit_rating = "Average" customer.credit_rating # => "Average"
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# File activerecord/lib/active_record/base.rb, line 1086 1086: def attr_accessible(*attributes) 1087: write_inheritable_attribute(:attr_accessible, Set.new(attributes.map(&:to_s)) + (accessible_attributes || [])) 1088: end
Attributes named in this macro are protected from mass-assignment, such as new(attributes), update_attributes(attributes), or attributes=(attributes).
Mass-assignment to these attributes will simply be ignored, to assign to them you can use direct writer methods. This is meant to protect sensitive attributes from being overwritten by malicious users tampering with URLs or forms.
class Customer < ActiveRecord::Base attr_protected :credit_rating end customer = Customer.new("name" => David, "credit_rating" => "Excellent") customer.credit_rating # => nil customer.attributes = { "description" => "Jolly fellow", "credit_rating" => "Superb" } customer.credit_rating # => nil customer.credit_rating = "Average" customer.credit_rating # => "Average"
To start from an all-closed default and enable attributes as needed, have a look at attr_accessible.
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# File activerecord/lib/active_record/base.rb, line 1053 1053: def attr_protected(*attributes) 1054: write_inheritable_attribute(:attr_protected, Set.new(attributes.map(&:to_s)) + (protected_attributes || [])) 1055: end
Attributes listed as readonly can be set for a new record, but will be ignored in database updates afterwards.
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# File activerecord/lib/active_record/base.rb, line 1096 1096: def attr_readonly(*attributes) 1097: write_inheritable_attribute(:attr_readonly, Set.new(attributes.map(&:to_s)) + (readonly_attributes || [])) 1098: end
Returns the base AR subclass that this class descends from. If A extends AR::Base, A.base_class will return A. If B descends from A through some arbitrarily deep hierarchy, B.base_class will return A.
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# File activerecord/lib/active_record/base.rb, line 1496 1496: def base_class 1497: class_of_active_record_descendant(self) 1498: end
Log and benchmark multiple statements in a single block. Example:
Project.benchmark("Creating project") do project = Project.create("name" => "stuff") project.create_manager("name" => "David") project.milestones << Milestone.find(:all) end
The benchmark is only recorded if the current level of the logger is less than or equal to the log_level, which makes it easy to include benchmarking statements in production software that will remain inexpensive because the benchmark will only be conducted if the log level is low enough.
The logging of the multiple statements is turned off unless use_silence is set to false.
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# File activerecord/lib/active_record/base.rb, line 1469 1469: def benchmark(title, log_level = Logger::DEBUG, use_silence = true) 1470: if logger && logger.level <= log_level 1471: result = nil 1472: ms = Benchmark.ms { result = use_silence ? silence { yield } : yield } 1473: logger.add(log_level, '%s (%.1fms)' % [title, ms]) 1474: result 1475: else 1476: yield 1477: end 1478: end
Returns an array of column names as strings.
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# File activerecord/lib/active_record/base.rb, line 1318 1318: def column_names 1319: @column_names ||= columns.map { |column| column.name } 1320: end
Returns an array of column objects for the table associated with this class.
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# File activerecord/lib/active_record/base.rb, line 1304 1304: def columns 1305: unless defined?(@columns) && @columns 1306: @columns = connection.columns(table_name, "#{name} Columns") 1307: @columns.each { |column| column.primary = column.name == primary_key } 1308: end 1309: @columns 1310: end
Returns a hash of column objects for the table associated with this class.
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# File activerecord/lib/active_record/base.rb, line 1313 1313: def columns_hash 1314: @columns_hash ||= columns.inject({}) { |hash, column| hash[column.name] = column; hash } 1315: end
Returns true if ActiveRecord is connected.
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# File activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 127 127: def connected? 128: connection_handler.connected?(self) 129: end
Returns the connection currently associated with the class. This can also be used to "borrow" the connection to do database work unrelated to any of the specific Active Records.
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# File activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 114 114: def connection 115: retrieve_connection 116: end
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# File activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 118 118: def connection_pool 119: connection_handler.retrieve_connection_pool(self) 120: end
Returns an array of column objects where the primary id, all columns ending in "_id" or "_count", and columns used for single table inheritance have been removed.
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# File activerecord/lib/active_record/base.rb, line 1324 1324: def content_columns 1325: @content_columns ||= columns.reject { |c| c.primary || c.name =~ /(_id|_count)$/ || c.name == inheritance_column } 1326: end
Returns the result of an SQL statement that should only include a COUNT(*) in the SELECT part. The use of this method should be restricted to complicated SQL queries that can‘t be executed using the ActiveRecord::Calculations class methods. Look into those before using this.
Parameters
- sql - An SQL statement which should return a count query from the database, see the example below.
Examples
Product.count_by_sql "SELECT COUNT(*) FROM sales s, customers c WHERE s.customer_id = c.id"
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# File activerecord/lib/active_record/base.rb, line 918 918: def count_by_sql(sql) 919: sql = sanitize_conditions(sql) 920: connection.select_value(sql, "#{name} Count").to_i 921: end
Creates an object (or multiple objects) and saves it to the database, if validations pass. The resulting object is returned whether the object was saved successfully to the database or not.
The attributes parameter can be either be a Hash or an Array of Hashes. These Hashes describe the attributes on the objects that are to be created.
Examples
# Create a single new object User.create(:first_name => 'Jamie') # Create an Array of new objects User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }]) # Create a single object and pass it into a block to set other attributes. User.create(:first_name => 'Jamie') do |u| u.is_admin = false end # Creating an Array of new objects using a block, where the block is executed for each object: User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }]) do |u| u.is_admin = false end
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# File activerecord/lib/active_record/base.rb, line 721 721: def create(attributes = nil, &block) 722: if attributes.is_a?(Array) 723: attributes.collect { |attr| create(attr, &block) } 724: else 725: object = new(attributes) 726: yield(object) if block_given? 727: object.save 728: object 729: end 730: end
Decrement a number field by one, usually representing a count.
This works the same as increment_counter but reduces the column value by 1 instead of increasing it.
Parameters
- counter_name - The name of the field that should be decremented.
- id - The id of the object that should be decremented.
Examples
# Decrement the post_count column for the record with an id of 5 DiscussionBoard.decrement_counter(:post_count, 5)
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# File activerecord/lib/active_record/base.rb, line 1025 1025: def decrement_counter(counter_name, id) 1026: update_counters(id, counter_name => -1) 1027: end
Deletes the row with a primary key matching the id argument, using a SQL DELETE statement, and returns the number of rows deleted. Active Record objects are not instantiated, so the object‘s callbacks are not executed, including any :dependent association options or Observer methods.
You can delete multiple rows at once by passing an Array of ids.
Note: Although it is often much faster than the alternative, destroy, skipping callbacks might bypass business logic in your application that ensures referential integrity or performs other essential jobs.
Examples
# Delete a single row Todo.delete(1) # Delete multiple rows Todo.delete([2,3,4])
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# File activerecord/lib/active_record/base.rb, line 779 779: def delete(id) 780: delete_all([ "#{connection.quote_column_name(primary_key)} IN (?)", id ]) 781: end
Deletes the records matching conditions without instantiating the records first, and hence not calling the destroy method nor invoking callbacks. This is a single SQL DELETE statement that goes straight to the database, much more efficient than destroy_all. Be careful with relations though, in particular :dependent rules defined on associations are not honored. Returns the number of rows affected.
Parameters
- conditions - Conditions are specified the same way as with find method.
Example
Post.delete_all("person_id = 5 AND (category = 'Something' OR category = 'Else')") Post.delete_all(["person_id = ? AND (category = ? OR category = ?)", 5, 'Something', 'Else'])
Both calls delete the affected posts all at once with a single DELETE statement. If you need to destroy dependent associations or call your before_* or after_destroy callbacks, use the destroy_all method instead.
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# File activerecord/lib/active_record/base.rb, line 901 901: def delete_all(conditions = nil) 902: sql = "DELETE FROM #{quoted_table_name} " 903: add_conditions!(sql, conditions, scope(:find)) 904: connection.delete(sql, "#{name} Delete all") 905: end
True if this isn‘t a concrete subclass needing a STI type condition.
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# File activerecord/lib/active_record/base.rb, line 1420 1420: def descends_from_active_record? 1421: if superclass.abstract_class? 1422: superclass.descends_from_active_record? 1423: else 1424: superclass == Base || !columns_hash.include?(inheritance_column) 1425: end 1426: end
Destroy an object (or multiple objects) that has the given id, the object is instantiated first, therefore all callbacks and filters are fired off before the object is deleted. This method is less efficient than ActiveRecord#delete but allows cleanup methods and other actions to be run.
This essentially finds the object (or multiple objects) with the given id, creates a new object from the attributes, and then calls destroy on it.
Parameters
- id - Can be either an Integer or an Array of Integers.
Examples
# Destroy a single object Todo.destroy(1) # Destroy multiple objects todos = [1,2,3] Todo.destroy(todos)
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# File activerecord/lib/active_record/base.rb, line 802 802: def destroy(id) 803: if id.is_a?(Array) 804: id.map { |one_id| destroy(one_id) } 805: else 806: find(id).destroy 807: end 808: end
Destroys the records matching conditions by instantiating each record and calling its destroy method. Each object‘s callbacks are executed (including :dependent association options and before_destroy/after_destroy Observer methods). Returns the collection of objects that were destroyed; each will be frozen, to reflect that no changes should be made (since they can‘t be persisted).
Note: Instantiation, callback execution, and deletion of each record can be time consuming when you‘re removing many records at once. It generates at least one SQL DELETE query per record (or possibly more, to enforce your callbacks). If you want to delete many rows quickly, without concern for their associations or callbacks, use delete_all instead.
Parameters
- conditions - A string, array, or hash that specifies which records to destroy. If omitted, all records are destroyed. See the Conditions section in the introduction to ActiveRecord::Base for more information.
Examples
Person.destroy_all("last_login < '2004-04-04'") Person.destroy_all(:status => "inactive")
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# File activerecord/lib/active_record/base.rb, line 880 880: def destroy_all(conditions = nil) 881: find(:all, :conditions => conditions).each { |object| object.destroy } 882: end
Establishes the connection to the database. Accepts a hash as input where the :adapter key must be specified with the name of a database adapter (in lower-case) example for regular databases (MySQL, Postgresql, etc):
ActiveRecord::Base.establish_connection( :adapter => "mysql", :host => "localhost", :username => "myuser", :password => "mypass", :database => "somedatabase" )
Example for SQLite database:
ActiveRecord::Base.establish_connection( :adapter => "sqlite", :database => "path/to/dbfile" )
Also accepts keys as strings (for parsing from YAML for example):
ActiveRecord::Base.establish_connection( "adapter" => "sqlite", "database" => "path/to/dbfile" )
The exceptions AdapterNotSpecified, AdapterNotFound and ArgumentError may be returned on an error.
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# File activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 51 51: def self.establish_connection(spec = nil) 52: case spec 53: when nil 54: raise AdapterNotSpecified unless defined? RAILS_ENV 55: establish_connection(RAILS_ENV) 56: when ConnectionSpecification 57: self.connection_handler.establish_connection(name, spec) 58: when Symbol, String 59: if configuration = configurations[spec.to_s] 60: establish_connection(configuration) 61: else 62: raise AdapterNotSpecified, "#{spec} database is not configured" 63: end 64: else 65: spec = spec.symbolize_keys 66: unless spec.key?(:adapter) then raise AdapterNotSpecified, "database configuration does not specify adapter" end 67: 68: begin 69: require 'rubygems' 70: gem "activerecord-#{spec[:adapter]}-adapter" 71: require "active_record/connection_adapters/#{spec[:adapter]}_adapter" 72: rescue LoadError 73: begin 74: require "active_record/connection_adapters/#{spec[:adapter]}_adapter" 75: rescue LoadError 76: raise "Please install the #{spec[:adapter]} adapter: `gem install activerecord-#{spec[:adapter]}-adapter` (#{$!})" 77: end 78: end 79: 80: adapter_method = "#{spec[:adapter]}_connection" 81: if !respond_to?(adapter_method) 82: raise AdapterNotFound, "database configuration specifies nonexistent #{spec[:adapter]} adapter" 83: end 84: 85: remove_connection 86: establish_connection(ConnectionSpecification.new(spec, adapter_method)) 87: end 88: end
Returns true if a record exists in the table that matches the id or conditions given, or false otherwise. The argument can take five forms:
- Integer - Finds the record with this primary key.
- String - Finds the record with a primary key corresponding to this string (such as ‘5‘).
- Array - Finds the record that matches these find-style conditions (such as [‘color = ?’, ‘red’]).
- Hash - Finds the record that matches these find-style conditions (such as {:color => ‘red’}).
- No args - Returns false if the table is empty, true otherwise.
For more information about specifying conditions as a Hash or Array, see the Conditions section in the introduction to ActiveRecord::Base.
Note: You can‘t pass in a condition as a string (like name = ‘Jamie‘), since it would be sanitized and then queried against the primary key column, like id = ‘name = \’Jamie\’‘.
Examples
Person.exists?(5) Person.exists?('5') Person.exists?(:name => "David") Person.exists?(['name LIKE ?', "%#{query}%"]) Person.exists?
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# File activerecord/lib/active_record/base.rb, line 693 693: def exists?(id_or_conditions = {}) 694: find_initial( 695: :select => "#{quoted_table_name}.#{primary_key}", 696: :conditions => expand_id_conditions(id_or_conditions)) ? true : false 697: end
Find operates with four different retrieval approaches:
- Find by id - This can either be a specific id (1), a list of ids (1, 5, 6), or an array of ids ([5, 6, 10]). If no record can be found for all of the listed ids, then RecordNotFound will be raised.
- Find first - This will return the first record matched by the options used. These options can either be specific conditions or merely an order. If no record can be matched, nil is returned. Use Model.find(:first, *args) or its shortcut Model.first(*args).
- Find last - This will return the last record matched by the options used. These options can either be specific conditions or merely an order. If no record can be matched, nil is returned. Use Model.find(:last, *args) or its shortcut Model.last(*args).
- Find all - This will return all the records matched by the options used. If no records are found, an empty array is returned. Use Model.find(:all, *args) or its shortcut Model.all(*args).
All approaches accept an options hash as their last parameter.
Parameters
- :conditions - An SQL fragment like "administrator = 1", [ "user_name = ?", username ], or ["user_name = :user_name", { :user_name => user_name }]. See conditions in the intro.
- :order - An SQL fragment like "created_at DESC, name".
- :group - An attribute name by which the result should be grouped. Uses the GROUP BY SQL-clause.
- :having - Combined with +:group+ this can be used to filter the records that a GROUP BY returns. Uses the HAVING SQL-clause.
- :limit - An integer determining the limit on the number of rows that should be returned.
- :offset - An integer determining the offset from where the rows should be fetched. So at 5, it would skip rows 0 through 4.
- :joins - Either an SQL fragment for additional joins like "LEFT JOIN comments ON comments.post_id = id" (rarely needed), named associations in the same form used for the :include option, which will perform an INNER JOIN on the associated table(s), or an array containing a mixture of both strings and named associations. If the value is a string, then the records will be returned read-only since they will have attributes that do not correspond to the table‘s columns. Pass :readonly => false to override.
- :include - Names associations that should be loaded alongside. The symbols named refer to already defined associations. See eager loading under Associations.
- :select - By default, this is "*" as in "SELECT * FROM", but can be changed if you, for example, want to do a join but not include the joined columns. Takes a string with the SELECT SQL fragment (e.g. "id, name").
- :from - By default, this is the table name of the class, but can be changed to an alternate table name (or even the name of a database view).
- :readonly - Mark the returned records read-only so they cannot be saved or updated.
- :lock - An SQL fragment like "FOR UPDATE" or "LOCK IN SHARE MODE". :lock => true gives connection‘s default exclusive lock, usually "FOR UPDATE".
Examples
# find by id Person.find(1) # returns the object for ID = 1 Person.find(1, 2, 6) # returns an array for objects with IDs in (1, 2, 6) Person.find([7, 17]) # returns an array for objects with IDs in (7, 17) Person.find([1]) # returns an array for the object with ID = 1 Person.find(1, :conditions => "administrator = 1", :order => "created_on DESC")
Note that returned records may not be in the same order as the ids you provide since database rows are unordered. Give an explicit :order to ensure the results are sorted.
Examples
# find first Person.find(:first) # returns the first object fetched by SELECT * FROM people Person.find(:first, :conditions => [ "user_name = ?", user_name]) Person.find(:first, :conditions => [ "user_name = :u", { :u => user_name }]) Person.find(:first, :order => "created_on DESC", :offset => 5) # find last Person.find(:last) # returns the last object fetched by SELECT * FROM people Person.find(:last, :conditions => [ "user_name = ?", user_name]) Person.find(:last, :order => "created_on DESC", :offset => 5) # find all Person.find(:all) # returns an array of objects for all the rows fetched by SELECT * FROM people Person.find(:all, :conditions => [ "category IN (?)", categories], :limit => 50) Person.find(:all, :conditions => { :friends => ["Bob", "Steve", "Fred"] } Person.find(:all, :offset => 10, :limit => 10) Person.find(:all, :include => [ :account, :friends ]) Person.find(:all, :group => "category")
Example for find with a lock: Imagine two concurrent transactions: each will read person.visits == 2, add 1 to it, and save, resulting in two saves of person.visits = 3. By locking the row, the second transaction has to wait until the first is finished; we get the expected person.visits == 4.
Person.transaction do person = Person.find(1, :lock => true) person.visits += 1 person.save! end
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# File activerecord/lib/active_record/base.rb, line 611 611: def find(*args) 612: options = args.extract_options! 613: validate_find_options(options) 614: set_readonly_option!(options) 615: 616: case args.first 617: when :first then find_initial(options) 618: when :last then find_last(options) 619: when :all then find_every(options) 620: else find_from_ids(args, options) 621: end 622: end
Executes a custom SQL query against your database and returns all the results. The results will be returned as an array with columns requested encapsulated as attributes of the model you call this method from. If you call Product.find_by_sql then the results will be returned in a Product object with the attributes you specified in the SQL query.
If you call a complicated SQL query which spans multiple tables the columns specified by the SELECT will be attributes of the model, whether or not they are columns of the corresponding table.
The sql parameter is a full SQL query as a string. It will be called as is, there will be no database agnostic conversions performed. This should be a last resort because using, for example, MySQL specific terms will lock you to using that particular database engine or require you to change your call if you switch engines.
Examples
# A simple SQL query spanning multiple tables Post.find_by_sql "SELECT p.title, c.author FROM posts p, comments c WHERE p.id = c.post_id" > [#<Post:0x36bff9c @attributes={"title"=>"Ruby Meetup", "first_name"=>"Quentin"}>, ...] # You can use the same string replacement techniques as you can with ActiveRecord#find Post.find_by_sql ["SELECT title FROM posts WHERE author = ? AND created > ?", author_id, start_date] > [#<Post:0x36bff9c @attributes={"first_name"=>"The Cheap Man Buys Twice"}>, ...]
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# File activerecord/lib/active_record/base.rb, line 664 664: def find_by_sql(sql) 665: connection.select_all(sanitize_sql(sql), "#{name} Load").collect! { |record| instantiate(record) } 666: end
A convenience wrapper for find(:first, *args). You can pass in all the same arguments to this method as you can to find(:first).
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# File activerecord/lib/active_record/base.rb, line 626 626: def first(*args) 627: find(:first, *args) 628: end
Transforms attribute key names into a more humane format, such as "First name" instead of "first_name". Example:
Person.human_attribute_name("first_name") # => "First name"
This used to be depricated in favor of humanize, but is now preferred, because it automatically uses the I18n module now. Specify options with additional translating options.
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# File activerecord/lib/active_record/base.rb, line 1396 1396: def human_attribute_name(attribute_key_name, options = {}) 1397: defaults = self_and_descendants_from_active_record.map do |klass| 1398: "#{klass.name.underscore}.#{attribute_key_name}""#{klass.name.underscore}.#{attribute_key_name}" 1399: end 1400: defaults << options[:default] if options[:default] 1401: defaults.flatten! 1402: defaults << attribute_key_name.to_s.humanize 1403: options[:count] ||= 1 1404: I18n.translate(defaults.shift, options.merge(:default => defaults, :scope => [:activerecord, :attributes])) 1405: end
Transform the modelname into a more humane format, using I18n. Defaults to the basic humanize method. Default scope of the translation is activerecord.models Specify options with additional translating options.
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# File activerecord/lib/active_record/base.rb, line 1411 1411: def human_name(options = {}) 1412: defaults = self_and_descendants_from_active_record.map do |klass| 1413: "#{klass.name.underscore}""#{klass.name.underscore}" 1414: end 1415: defaults << self.name.humanize 1416: I18n.translate(defaults.shift, {:scope => [:activerecord, :models], :count => 1, :default => defaults}.merge(options)) 1417: end
Increment a number field by one, usually representing a count.
This is used for caching aggregate values, so that they don‘t need to be computed every time. For example, a DiscussionBoard may cache post_count and comment_count otherwise every time the board is shown it would have to run an SQL query to find how many posts and comments there are.
Parameters
- counter_name - The name of the field that should be incremented.
- id - The id of the object that should be incremented.
Examples
# Increment the post_count column for the record with an id of 5 DiscussionBoard.increment_counter(:post_count, 5)
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# File activerecord/lib/active_record/base.rb, line 1008 1008: def increment_counter(counter_name, id) 1009: update_counters(id, counter_name => 1) 1010: end
Defines the column name for use with single table inheritance — can be set in subclasses like so: self.inheritance_column = "type_id"
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# File activerecord/lib/active_record/base.rb, line 1216 1216: def inheritance_column 1217: @inheritance_column ||= "type".freeze 1218: end
Returns a string like ‘Post id:integer, title:string, body:text‘
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# File activerecord/lib/active_record/base.rb, line 1434 1434: def inspect 1435: if self == Base 1436: super 1437: elsif abstract_class? 1438: "#{super}(abstract)" 1439: elsif table_exists? 1440: attr_list = columns.map { |c| "#{c.name}: #{c.type}" } * ', ' 1441: "#{super}(#{attr_list})" 1442: else 1443: "#{super}(Table doesn't exist)" 1444: end 1445: end
A convenience wrapper for find(:last, *args). You can pass in all the same arguments to this method as you can to find(:last).
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# File activerecord/lib/active_record/base.rb, line 632 632: def last(*args) 633: find(:last, *args) 634: end
Merges conditions so that the result is a valid condition
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# File activerecord/lib/active_record/base.rb, line 1524 1524: def merge_conditions(*conditions) 1525: segments = [] 1526: 1527: conditions.each do |condition| 1528: unless condition.blank? 1529: sql = sanitize_sql(condition) 1530: segments << sql unless sql.blank? 1531: end 1532: end 1533: 1534: "(#{segments.join(') AND (')})" unless segments.empty? 1535: end
New objects can be instantiated as either empty (pass no construction parameter) or pre-set with attributes but not yet saved (pass a hash with key names matching the associated table column names). In both instances, valid attribute keys are determined by the column names of the associated table — hence you can‘t have attributes that aren‘t part of the table columns.
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# File activerecord/lib/active_record/base.rb, line 2476 2476: def initialize(attributes = nil) 2477: @attributes = attributes_from_column_definition 2478: @attributes_cache = {} 2479: @new_record = true 2480: ensure_proper_type 2481: self.attributes = attributes unless attributes.nil? 2482: assign_attributes(self.class.send(:scope, :create)) if self.class.send(:scoped?, :create) 2483: result = yield self if block_given? 2484: callback(:after_initialize) if respond_to_without_attributes?(:after_initialize) 2485: result 2486: end
Defines the primary key field — can be overridden in subclasses. Overwriting will negate any effect of the primary_key_prefix_type setting, though.
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# File activerecord/lib/active_record/base.rb, line 1189 1189: def primary_key 1190: reset_primary_key 1191: end
Returns an array of all the attributes that have been specified as readonly.
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# File activerecord/lib/active_record/base.rb, line 1101 1101: def readonly_attributes 1102: read_inheritable_attribute(:attr_readonly) 1103: end
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# File activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 131 131: def remove_connection(klass = self) 132: connection_handler.remove_connection(klass) 133: end
Resets all the cached information about columns, which will cause them to be reloaded on the next request.
The most common usage pattern for this method is probably in a migration, when just after creating a table you want to populate it with some default values, eg:
class CreateJobLevels < ActiveRecord::Migration def self.up create_table :job_levels do |t| t.integer :id t.string :name t.timestamps end JobLevel.reset_column_information %w{assistant executive manager director}.each do |type| JobLevel.create(:name => type) end end def self.down drop_table :job_levels end end
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# File activerecord/lib/active_record/base.rb, line 1368 1368: def reset_column_information 1369: generated_methods.each { |name| undef_method(name) } 1370: @column_names = @columns = @columns_hash = @content_columns = @dynamic_methods_hash = @generated_methods = @inheritance_column = nil 1371: end
Resets one or more counter caches to their correct value using an SQL count query. This is useful when adding new counter caches, or if the counter has been corrupted or modified directly by SQL.
Parameters
- id - The id of the object you wish to reset a counter on.
- counters - One or more counter names to reset
Examples
# For Post with id #1 records reset the comments_count Post.reset_counters(1, :comments)
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# File activerecord/lib/active_record/base.rb, line 936 936: def reset_counters(id, *counters) 937: object = find(id) 938: counters.each do |association| 939: child_class = reflect_on_association(association.to_sym).klass 940: belongs_name = self.name.demodulize.underscore.to_sym 941: counter_name = child_class.reflect_on_association(belongs_name).counter_cache_column 942: value = object.send(association).count 943: 944: connection.update("UPDATE \#{quoted_table_name}\nSET \#{connection.quote_column_name(counter_name)} = \#{value}\nWHERE \#{connection.quote_column_name(primary_key)} = \#{quote_value(object.id)}\n", "#{name} UPDATE") 945: end 946: return true 947: end
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# File activerecord/lib/active_record/base.rb, line 1509 1509: def respond_to?(method_id, include_private = false) 1510: if match = DynamicFinderMatch.match(method_id) 1511: return true if all_attributes_exists?(match.attribute_names) 1512: elsif match = DynamicScopeMatch.match(method_id) 1513: return true if all_attributes_exists?(match.attribute_names) 1514: end 1515: 1516: super 1517: end
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# File activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 122 122: def retrieve_connection 123: connection_handler.retrieve_connection(self) 124: end
If you have an attribute that needs to be saved to the database as an object, and retrieved as the same object, then specify the name of that attribute using this method and it will be handled automatically. The serialization is done through YAML. If class_name is specified, the serialized object must be of that class on retrieval or SerializationTypeMismatch will be raised.
Parameters
- attr_name - The field name that should be serialized.
- class_name - Optional, class name that the object type should be equal to.
Example
# Serialize a preferences attribute class User serialize :preferences end
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# File activerecord/lib/active_record/base.rb, line 1120 1120: def serialize(attr_name, class_name = Object) 1121: serialized_attributes[attr_name.to_s] = class_name 1122: end
Returns a hash of all the attributes that have been specified for serialization as keys and their class restriction as values.
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# File activerecord/lib/active_record/base.rb, line 1125 1125: def serialized_attributes 1126: read_inheritable_attribute(:attr_serialized) or write_inheritable_attribute(:attr_serialized, {}) 1127: end
Sets the name of the inheritance column to use to the given value, or (if the value # is nil or false) to the value returned by the given block.
class Project < ActiveRecord::Base set_inheritance_column do original_inheritance_column + "_id" end end
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# File activerecord/lib/active_record/base.rb, line 1264 1264: def set_inheritance_column(value = nil, &block) 1265: define_attr_method :inheritance_column, value, &block 1266: end
Sets the name of the primary key column to use to the given value, or (if the value is nil or false) to the value returned by the given block.
class Project < ActiveRecord::Base set_primary_key "sysid" end
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# File activerecord/lib/active_record/base.rb, line 1250 1250: def set_primary_key(value = nil, &block) 1251: define_attr_method :primary_key, value, &block 1252: end
Sets the name of the sequence to use when generating ids to the given value, or (if the value is nil or false) to the value returned by the given block. This is required for Oracle and is useful for any database which relies on sequences for primary key generation.
If a sequence name is not explicitly set when using Oracle or Firebird, it will default to the commonly used pattern of: #{table_name}_seq
If a sequence name is not explicitly set when using PostgreSQL, it will discover the sequence corresponding to your primary key for you.
class Project < ActiveRecord::Base set_sequence_name "projectseq" # default would have been "project_seq" end
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# File activerecord/lib/active_record/base.rb, line 1283 1283: def set_sequence_name(value = nil, &block) 1284: define_attr_method :sequence_name, value, &block 1285: end
Sets the table name to use to the given value, or (if the value is nil or false) to the value returned by the given block.
class Project < ActiveRecord::Base set_table_name "project" end
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# File activerecord/lib/active_record/base.rb, line 1238 1238: def set_table_name(value = nil, &block) 1239: define_attr_method :table_name, value, &block 1240: end
Silences the logger for the duration of the block.
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# File activerecord/lib/active_record/base.rb, line 1481 1481: def silence 1482: old_logger_level, logger.level = logger.level, Logger::ERROR if logger 1483: yield 1484: ensure 1485: logger.level = old_logger_level if logger 1486: end
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# File activerecord/lib/active_record/base.rb, line 1519 1519: def sti_name 1520: store_full_sti_class ? name : name.demodulize 1521: end
Indicates whether the table associated with this class exists
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# File activerecord/lib/active_record/base.rb, line 1299 1299: def table_exists? 1300: connection.table_exists?(table_name) 1301: end
Guesses the table name (in forced lower-case) based on the name of the class in the inheritance hierarchy descending directly from ActiveRecord::Base. So if the hierarchy looks like: Reply < Message < ActiveRecord::Base, then Message is used to guess the table name even when called on Reply. The rules used to do the guess are handled by the Inflector class in Active Support, which knows almost all common English inflections. You can add new inflections in config/initializers/inflections.rb.
Nested classes are given table names prefixed by the singular form of the parent‘s table name. Enclosing modules are not considered.
Examples
class Invoice < ActiveRecord::Base; end; file class table_name invoice.rb Invoice invoices class Invoice < ActiveRecord::Base; class Lineitem < ActiveRecord::Base; end; end; file class table_name invoice.rb Invoice::Lineitem invoice_lineitems module Invoice; class Lineitem < ActiveRecord::Base; end; end; file class table_name invoice/lineitem.rb Invoice::Lineitem lineitems
Additionally, the class-level table_name_prefix is prepended and the table_name_suffix is appended. So if you have "myapp_" as a prefix, the table name guess for an Invoice class becomes "myapp_invoices". Invoice::Lineitem becomes "myapp_invoice_lineitems".
You can also overwrite this class method to allow for unguessable links, such as a Mouse class with a link to a "mice" table. Example:
class Mouse < ActiveRecord::Base set_table_name "mice" end
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# File activerecord/lib/active_record/base.rb, line 1162 1162: def table_name 1163: reset_table_name 1164: end
Updates an object (or multiple objects) and saves it to the database, if validations pass. The resulting object is returned whether the object was saved successfully to the database or not.
Parameters
- id - This should be the id or an array of ids to be updated.
- attributes - This should be a hash of attributes to be set on the object, or an array of hashes.
Examples
# Updating one record: Person.update(15, :user_name => 'Samuel', :group => 'expert') # Updating multiple records: people = { 1 => { "first_name" => "David" }, 2 => { "first_name" => "Jeremy" } } Person.update(people.keys, people.values)
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# File activerecord/lib/active_record/base.rb, line 748 748: def update(id, attributes) 749: if id.is_a?(Array) 750: idx = -1 751: id.collect { |one_id| idx += 1; update(one_id, attributes[idx]) } 752: else 753: object = find(id) 754: object.update_attributes(attributes) 755: object 756: end 757: end
Updates all records with details given if they match a set of conditions supplied, limits and order can also be supplied. This method constructs a single SQL UPDATE statement and sends it straight to the database. It does not instantiate the involved models and it does not trigger Active Record callbacks.
Parameters
- updates - A string of column and value pairs that will be set on any records that match conditions. This creates the SET clause of the generated SQL.
- conditions - An SQL fragment like "administrator = 1" or [ "user_name = ?", username ]. See conditions in the intro for more info.
- options - Additional options are :limit and :order, see the examples for usage.
Examples
# Update all billing objects with the 3 different attributes given Billing.update_all( "category = 'authorized', approved = 1, author = 'David'" ) # Update records that match our conditions Billing.update_all( "author = 'David'", "title LIKE '%Rails%'" ) # Update records that match our conditions but limit it to 5 ordered by date Billing.update_all( "author = 'David'", "title LIKE '%Rails%'", :order => 'created_at', :limit => 5 )
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# File activerecord/lib/active_record/base.rb, line 831 831: def update_all(updates, conditions = nil, options = {}) 832: sql = "UPDATE #{quoted_table_name} SET #{sanitize_sql_for_assignment(updates)} " 833: 834: scope = scope(:find) 835: 836: select_sql = "" 837: add_conditions!(select_sql, conditions, scope) 838: 839: if options.has_key?(:limit) || (scope && scope[:limit]) 840: # Only take order from scope if limit is also provided by scope, this 841: # is useful for updating a has_many association with a limit. 842: add_order!(select_sql, options[:order], scope) 843: 844: add_limit!(select_sql, options, scope) 845: sql.concat(connection.limited_update_conditions(select_sql, quoted_table_name, connection.quote_column_name(primary_key))) 846: else 847: add_order!(select_sql, options[:order], nil) 848: sql.concat(select_sql) 849: end 850: 851: connection.update(sql, "#{name} Update") 852: end
A generic "counter updater" implementation, intended primarily to be used by increment_counter and decrement_counter, but which may also be useful on its own. It simply does a direct SQL update for the record with the given ID, altering the given hash of counters by the amount given by the corresponding value:
Parameters
- id - The id of the object you wish to update a counter on or an Array of ids.
- counters - An Array of Hashes containing the names of the fields to update as keys and the amount to update the field by as values.
Examples
# For the Post with id of 5, decrement the comment_count by 1, and # increment the action_count by 1 Post.update_counters 5, :comment_count => -1, :action_count => 1 # Executes the following SQL: # UPDATE posts # SET comment_count = comment_count - 1, # action_count = action_count + 1 # WHERE id = 5 # For the Posts with id of 10 and 15, increment the comment_count by 1 Post.update_counters [10, 15], :comment_count => 1 # Executes the following SQL: # UPDATE posts # SET comment_count = comment_count + 1, # WHERE id IN (10, 15)
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# File activerecord/lib/active_record/base.rb, line 983 983: def update_counters(id, counters) 984: updates = counters.map do |counter_name, value| 985: operator = value < 0 ? '-' : '+' 986: quoted_column = connection.quote_column_name(counter_name) 987: "#{quoted_column} = COALESCE(#{quoted_column}, 0) #{operator} #{value.abs}" 988: end 989: 990: update_all(updates.join(', '), primary_key => id ) 991: end
Deprecated and no longer has any effect.
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# File activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 102 102: def verification_timeout 103: ActiveSupport::Deprecation.warn("ActiveRecord::Base.verification_timeout has been deprecated and no longer has any effect. Please remove all references to verification_timeout.") 104: end
Deprecated and no longer has any effect.
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# File activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 107 107: def verification_timeout=(flag) 108: ActiveSupport::Deprecation.warn("ActiveRecord::Base.verification_timeout= has been deprecated and no longer has any effect. Please remove all references to verification_timeout=.") 109: end
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# File activerecord/lib/active_record/base.rb, line 2291 2291: def aggregate_mapping(reflection) 2292: mapping = reflection.options[:mapping] || [reflection.name, reflection.name] 2293: mapping.first.is_a?(Array) ? mapping : [mapping] 2294: end
Returns the class descending directly from ActiveRecord::Base or an abstract class, if any, in the inheritance hierarchy.
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# File activerecord/lib/active_record/base.rb, line 2249 2249: def class_of_active_record_descendant(klass) 2250: if klass.superclass == Base || klass.superclass.abstract_class? 2251: klass 2252: elsif klass.superclass.nil? 2253: raise ActiveRecordError, "#{name} doesn't belong in a hierarchy descending from ActiveRecord" 2254: else 2255: class_of_active_record_descendant(klass.superclass) 2256: end 2257: end
Returns the class type of the record using the current module as a prefix. So descendants of MyApp::Business::Account would appear as MyApp::Business::AccountSubclass.
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# File activerecord/lib/active_record/base.rb, line 2236 2236: def compute_type(type_name) 2237: modularized_name = type_name_with_module(type_name) 2238: silence_warnings do 2239: begin 2240: class_eval(modularized_name, __FILE__) 2241: rescue NameError 2242: class_eval(type_name, __FILE__) 2243: end 2244: end 2245: end
Sets the default options for the model. The format of the options argument is the same as in find.
class Person < ActiveRecord::Base default_scope :order => 'last_name, first_name' end
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# File activerecord/lib/active_record/base.rb, line 2208 2208: def default_scope(options = {}) 2209: self.default_scoping << { :find => options, :create => options[:conditions].is_a?(Hash) ? options[:conditions] : {} } 2210: end
Accepts a hash of SQL conditions and replaces those attributes that correspond to a composed_of relationship with their expanded aggregate attribute values. Given:
class Person < ActiveRecord::Base composed_of :address, :class_name => "Address", :mapping => [%w(address_street street), %w(address_city city)] end
Then:
{ :address => Address.new("813 abc st.", "chicago") } # => { :address_street => "813 abc st.", :address_city => "chicago" }
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# File activerecord/lib/active_record/base.rb, line 2307 2307: def expand_hash_conditions_for_aggregates(attrs) 2308: expanded_attrs = {} 2309: attrs.each do |attr, value| 2310: unless (aggregation = reflect_on_aggregation(attr.to_sym)).nil? 2311: mapping = aggregate_mapping(aggregation) 2312: mapping.each do |field_attr, aggregate_attr| 2313: if mapping.size == 1 && !value.respond_to?(aggregate_attr) 2314: expanded_attrs[field_attr] = value 2315: else 2316: expanded_attrs[field_attr] = value.send(aggregate_attr) 2317: end 2318: end 2319: else 2320: expanded_attrs[attr] = value 2321: end 2322: end 2323: expanded_attrs 2324: end
Accepts an array of conditions. The array has each value sanitized and interpolated into the SQL statement.
["name='%s' and group_id='%s'", "foo'bar", 4] returns "name='foo''bar' and group_id='4'"
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# File activerecord/lib/active_record/base.rb, line 2379 2379: def sanitize_sql_array(ary) 2380: statement, *values = ary 2381: if values.first.is_a?(Hash) and statement =~ /:\w+/ 2382: replace_named_bind_variables(statement, values.first) 2383: elsif statement.include?('?') 2384: replace_bind_variables(statement, values) 2385: else 2386: statement % values.collect { |value| connection.quote_string(value.to_s) } 2387: end 2388: end
Accepts an array, hash, or string of SQL conditions and sanitizes them into a valid SQL fragment for a SET clause.
{ :name => nil, :group_id => 4 } returns "name = NULL , group_id='4'"
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# File activerecord/lib/active_record/base.rb, line 2283 2283: def sanitize_sql_for_assignment(assignments) 2284: case assignments 2285: when Array; sanitize_sql_array(assignments) 2286: when Hash; sanitize_sql_hash_for_assignment(assignments) 2287: else assignments 2288: end 2289: end
Accepts an array, hash, or string of SQL conditions and sanitizes them into a valid SQL fragment for a WHERE clause.
["name='%s' and group_id='%s'", "foo'bar", 4] returns "name='foo''bar' and group_id='4'" { :name => "foo'bar", :group_id => 4 } returns "name='foo''bar' and group_id='4'" "name='foo''bar' and group_id='4'" returns "name='foo''bar' and group_id='4'"
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# File activerecord/lib/active_record/base.rb, line 2269 2269: def sanitize_sql_for_conditions(condition, table_name = quoted_table_name) 2270: return nil if condition.blank? 2271: 2272: case condition 2273: when Array; sanitize_sql_array(condition) 2274: when Hash; sanitize_sql_hash_for_conditions(condition, table_name) 2275: else condition 2276: end 2277: end
Sanitizes a hash of attribute/value pairs into SQL conditions for a SET clause.
{ :status => nil, :group_id => 1 } # => "status = NULL , group_id = 1"
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# File activerecord/lib/active_record/base.rb, line 2370 2370: def sanitize_sql_hash_for_assignment(attrs) 2371: attrs.map do |attr, value| 2372: "#{connection.quote_column_name(attr)} = #{quote_bound_value(value)}" 2373: end.join(', ') 2374: end
Sanitizes a hash of attribute/value pairs into SQL conditions for a WHERE clause.
{ :name => "foo'bar", :group_id => 4 } # => "name='foo''bar' and group_id= 4" { :status => nil, :group_id => [1,2,3] } # => "status IS NULL and group_id IN (1,2,3)" { :age => 13..18 } # => "age BETWEEN 13 AND 18" { 'other_records.id' => 7 } # => "`other_records`.`id` = 7" { :other_records => { :id => 7 } } # => "`other_records`.`id` = 7"
And for value objects on a composed_of relationship:
{ :address => Address.new("123 abc st.", "chicago") } # => "address_street='123 abc st.' and address_city='chicago'"
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# File activerecord/lib/active_record/base.rb, line 2340 2340: def sanitize_sql_hash_for_conditions(attrs, default_table_name = quoted_table_name) 2341: attrs = expand_hash_conditions_for_aggregates(attrs) 2342: 2343: conditions = attrs.map do |attr, value| 2344: table_name = default_table_name 2345: 2346: unless value.is_a?(Hash) 2347: attr = attr.to_s 2348: 2349: # Extract table name from qualified attribute names. 2350: if attr.include?('.') 2351: attr_table_name, attr = attr.split('.', 2) 2352: attr_table_name = connection.quote_table_name(attr_table_name) 2353: else 2354: attr_table_name = table_name 2355: end 2356: 2357: attribute_condition("#{attr_table_name}.#{connection.quote_column_name(attr)}", value) 2358: else 2359: sanitize_sql_hash_for_conditions(value, connection.quote_table_name(attr.to_s)) 2360: end 2361: end.join(' AND ') 2362: 2363: replace_bind_variables(conditions, expand_range_bind_variables(attrs.values)) 2364: end
Works like with_scope, but discards any nested properties.
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# File activerecord/lib/active_record/base.rb, line 2193 2193: def with_exclusive_scope(method_scoping = {}, &block) 2194: with_scope(method_scoping, :overwrite, &block) 2195: end
Scope parameters to method calls within the block. Takes a hash of method_name => parameters hash. method_name may be :find or :create. :find parameters may include the :conditions, :joins, :include, :offset, :limit, and :readonly options. :create parameters are an attributes hash.
class Article < ActiveRecord::Base def self.create_with_scope with_scope(:find => { :conditions => "blog_id = 1" }, :create => { :blog_id => 1 }) do find(1) # => SELECT * from articles WHERE blog_id = 1 AND id = 1 a = create(1) a.blog_id # => 1 end end end
In nested scopings, all previous parameters are overwritten by the innermost rule, with the exception of :conditions, :include, and :joins options in :find, which are merged.
:joins options are uniqued so multiple scopes can join in the same table without table aliasing problems. If you need to join multiple tables, but still want one of the tables to be uniqued, use the array of strings format for your joins.
class Article < ActiveRecord::Base def self.find_with_scope with_scope(:find => { :conditions => "blog_id = 1", :limit => 1 }, :create => { :blog_id => 1 }) do with_scope(:find => { :limit => 10 }) find(:all) # => SELECT * from articles WHERE blog_id = 1 LIMIT 10 end with_scope(:find => { :conditions => "author_id = 3" }) find(:all) # => SELECT * from articles WHERE blog_id = 1 AND author_id = 3 LIMIT 1 end end end end
You can ignore any previous scopings by using the with_exclusive_scope method.
class Article < ActiveRecord::Base def self.find_with_exclusive_scope with_scope(:find => { :conditions => "blog_id = 1", :limit => 1 }) do with_exclusive_scope(:find => { :limit => 10 }) find(:all) # => SELECT * from articles LIMIT 10 end end end end
Note: the +:find+ scope also has effect on update and deletion methods, like update_all and delete_all.
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# File activerecord/lib/active_record/base.rb, line 2132 2132: def with_scope(method_scoping = {}, action = :merge, &block) 2133: method_scoping = method_scoping.method_scoping if method_scoping.respond_to?(:method_scoping) 2134: 2135: # Dup first and second level of hash (method and params). 2136: method_scoping = method_scoping.inject({}) do |hash, (method, params)| 2137: hash[method] = (params == true) ? params : params.dup 2138: hash 2139: end 2140: 2141: method_scoping.assert_valid_keys([ :find, :create ]) 2142: 2143: if f = method_scoping[:find] 2144: f.assert_valid_keys(VALID_FIND_OPTIONS) 2145: set_readonly_option! f 2146: end 2147: 2148: # Merge scopings 2149: if [:merge, :reverse_merge].include?(action) && current_scoped_methods 2150: method_scoping = current_scoped_methods.inject(method_scoping) do |hash, (method, params)| 2151: case hash[method] 2152: when Hash 2153: if method == :find 2154: (hash[method].keys + params.keys).uniq.each do |key| 2155: merge = hash[method][key] && params[key] # merge if both scopes have the same key 2156: if key == :conditions && merge 2157: if params[key].is_a?(Hash) && hash[method][key].is_a?(Hash) 2158: hash[method][key] = merge_conditions(hash[method][key].deep_merge(params[key])) 2159: else 2160: hash[method][key] = merge_conditions(params[key], hash[method][key]) 2161: end 2162: elsif key == :include && merge 2163: hash[method][key] = merge_includes(hash[method][key], params[key]).uniq 2164: elsif key == :joins && merge 2165: hash[method][key] = merge_joins(params[key], hash[method][key]) 2166: else 2167: hash[method][key] = hash[method][key] || params[key] 2168: end 2169: end 2170: else 2171: if action == :reverse_merge 2172: hash[method] = hash[method].merge(params) 2173: else 2174: hash[method] = params.merge(hash[method]) 2175: end 2176: end 2177: else 2178: hash[method] = params 2179: end 2180: hash 2181: end 2182: end 2183: 2184: self.scoped_methods << method_scoping 2185: begin 2186: yield 2187: ensure 2188: self.scoped_methods.pop 2189: end 2190: end
Returns true if the comparison_object is the same object, or is of the same type and has the same id.
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# File activerecord/lib/active_record/base.rb, line 2857 2857: def ==(comparison_object) 2858: comparison_object.equal?(self) || 2859: (comparison_object.instance_of?(self.class) && 2860: comparison_object.id == id && 2861: !comparison_object.new_record?) 2862: end
Returns the value of the attribute identified by attr_name after it has been typecast (for example, "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)). (Alias for the protected read_attribute method).
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# File activerecord/lib/active_record/base.rb, line 2755 2755: def [](attr_name) 2756: read_attribute(attr_name) 2757: end
Updates the attribute identified by attr_name with the specified value. (Alias for the protected write_attribute method).
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# File activerecord/lib/active_record/base.rb, line 2761 2761: def []=(attr_name, value) 2762: write_attribute(attr_name, value) 2763: end
Returns an inspect-like string for the value of the attribute attr_name. String attributes are elided after 50 characters, and Date and Time attributes are returned in the :db format. Other attributes return the value of inspect without modification.
person = Person.create!(:name => "David Heinemeier Hansson " * 3) person.attribute_for_inspect(:name) # => '"David Heinemeier Hansson David Heinemeier Hansson D..."' person.attribute_for_inspect(:created_at) # => '"2009-01-12 04:48:57"'
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# File activerecord/lib/active_record/base.rb, line 2822 2822: def attribute_for_inspect(attr_name) 2823: value = read_attribute(attr_name) 2824: 2825: if value.is_a?(String) && value.length > 50 2826: "#{value[0..50]}...".inspect 2827: elsif value.is_a?(Date) || value.is_a?(Time) 2828: %("#{value.to_s(:db)}") 2829: else 2830: value.inspect 2831: end 2832: end
Returns an array of names for the attributes available on this object sorted alphabetically.
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# File activerecord/lib/active_record/base.rb, line 2847 2847: def attribute_names 2848: @attributes.keys.sort 2849: end
Returns true if the specified attribute has been set by the user or by a database load and is neither nil nor empty? (the latter only applies to objects that respond to empty?, most notably Strings).
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# File activerecord/lib/active_record/base.rb, line 2836 2836: def attribute_present?(attribute) 2837: value = read_attribute(attribute) 2838: !value.blank? 2839: end
Returns a hash of all the attributes with their names as keys and the values of the attributes as values.
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# File activerecord/lib/active_record/base.rb, line 2795 2795: def attributes 2796: attrs = {} 2797: attribute_names.each { |name| attrs[name] = read_attribute(name) } 2798: attrs 2799: end
Allows you to set all the attributes at once by passing in a hash with keys matching the attribute names (which again matches the column names).
If guard_protected_attributes is true (the default), then sensitive attributes can be protected from this form of mass-assignment by using the attr_protected macro. Or you can alternatively specify which attributes can be accessed with the attr_accessible macro. Then all the attributes not included in that won‘t be allowed to be mass-assigned.
class User < ActiveRecord::Base attr_protected :is_admin end user = User.new user.attributes = { :username => 'Phusion', :is_admin => true } user.username # => "Phusion" user.is_admin? # => false user.send(:attributes=, { :username => 'Phusion', :is_admin => true }, false) user.is_admin? # => true
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# File activerecord/lib/active_record/base.rb, line 2785 2785: def attributes=(new_attributes, guard_protected_attributes = true) 2786: return if new_attributes.nil? 2787: attributes = new_attributes.dup 2788: attributes.stringify_keys! 2789: 2790: attributes = remove_attributes_protected_from_mass_assignment(attributes) if guard_protected_attributes 2791: assign_attributes(attributes) if attributes and attributes.any? 2792: end
Returns a hash of attributes before typecasting and deserialization.
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# File activerecord/lib/active_record/base.rb, line 2802 2802: def attributes_before_type_cast 2803: self.attribute_names.inject({}) do |attrs, name| 2804: attrs[name] = read_attribute_before_type_cast(name) 2805: attrs 2806: end 2807: end
Returns an instance of the specified klass with the attributes of the current record. This is mostly useful in relation to single-table inheritance structures where you want a subclass to appear as the superclass. This can be used along with record identification in Action Pack to allow, say, Client < Company to do something like render :partial => @client.becomes(Company) to render that instance using the companies/company partial instead of clients/client.
Note: The new instance will share a link to the same attributes as the original class. So any change to the attributes in either instance will affect the other.
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# File activerecord/lib/active_record/base.rb, line 2652 2652: def becomes(klass) 2653: klass.new.tap do |became| 2654: became.instance_variable_set("@attributes", @attributes) 2655: became.instance_variable_set("@attributes_cache", @attributes_cache) 2656: became.instance_variable_set("@new_record", new_record?) 2657: end 2658: end
Returns a cache key that can be used to identify this record.
Examples
Product.new.cache_key # => "products/new" Product.find(5).cache_key # => "products/5" (updated_at not available) Person.find(5).cache_key # => "people/5-20071224150000" (updated_at available)
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# File activerecord/lib/active_record/base.rb, line 2534 2534: def cache_key 2535: case 2536: when new_record? 2537: "#{self.class.model_name.cache_key}/new" 2538: when timestamp = self[:updated_at] 2539: "#{self.class.model_name.cache_key}/#{id}-#{timestamp.to_s(:number)}" 2540: else 2541: "#{self.class.model_name.cache_key}/#{id}" 2542: end 2543: end
Returns a clone of the record that hasn‘t been assigned an id yet and is treated as a new record. Note that this is a "shallow" clone: it copies the object‘s attributes only, not its associations. The extent of a "deep" clone is application-specific and is therefore left to the application to implement according to its need.
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# File activerecord/lib/active_record/base.rb, line 2637 2637: def clone 2638: attrs = clone_attributes(:read_attribute_before_type_cast) 2639: attrs.delete(self.class.primary_key) 2640: record = self.class.new 2641: record.send :instance_variable_set, '@attributes', attrs 2642: record 2643: end
Returns the column object for the named attribute.
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# File activerecord/lib/active_record/base.rb, line 2852 2852: def column_for_attribute(name) 2853: self.class.columns_hash[name.to_s] 2854: end
Returns the connection currently associated with the class. This can also be used to "borrow" the connection to do database work that isn‘t easily done without going straight to SQL.
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# File activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 19 19: def connection 20: self.class.connection 21: end
Initializes attribute to zero if nil and subtracts the value passed as by (default is 1). The decrement is performed directly on the underlying attribute, no setter is invoked. Only makes sense for number-based attributes. Returns self.
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# File activerecord/lib/active_record/base.rb, line 2709 2709: def decrement(attribute, by = 1) 2710: self[attribute] ||= 0 2711: self[attribute] -= by 2712: self 2713: end
Wrapper around decrement that saves the record. This method differs from its non-bang version in that it passes through the attribute setter. Saving is not subjected to validation checks. Returns true if the record could be saved.
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# File activerecord/lib/active_record/base.rb, line 2719 2719: def decrement!(attribute, by = 1) 2720: decrement(attribute, by).update_attribute(attribute, self[attribute]) 2721: end
Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can‘t be persisted). Returns the frozen instance.
The row is simply removed with a SQL DELETE statement on the record‘s primary key, and no callbacks are executed.
To enforce the object‘s before_destroy and after_destroy callbacks, Observer methods, or any :dependent association options, use destroy.
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# File activerecord/lib/active_record/base.rb, line 2611 2611: def delete 2612: self.class.delete(id) unless new_record? 2613: @destroyed = true 2614: freeze 2615: end
Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can‘t be persisted).
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# File activerecord/lib/active_record/base.rb, line 2619 2619: def destroy 2620: unless new_record? 2621: connection.delete( 2622: "DELETE FROM #{self.class.quoted_table_name} " + 2623: "WHERE #{connection.quote_column_name(self.class.primary_key)} = #{quoted_id}", 2624: "#{self.class.name} Destroy" 2625: ) 2626: end 2627: 2628: @destroyed = true 2629: freeze 2630: end
Returns true if the record has been destroyed.
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# File activerecord/lib/active_record/base.rb, line 2886 2886: def destroyed? 2887: @destroyed 2888: end
Delegates to ==
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# File activerecord/lib/active_record/base.rb, line 2865 2865: def eql?(comparison_object) 2866: self == (comparison_object) 2867: end
Freeze the attributes hash such that associations are still accessible, even on destroyed records.
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# File activerecord/lib/active_record/base.rb, line 2876 2876: def freeze 2877: @attributes.freeze; self 2878: end
Returns true if the attributes hash has been frozen.
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# File activerecord/lib/active_record/base.rb, line 2881 2881: def frozen? 2882: @attributes.frozen? 2883: end
Returns true if the given attribute is in the attributes hash
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# File activerecord/lib/active_record/base.rb, line 2842 2842: def has_attribute?(attr_name) 2843: @attributes.has_key?(attr_name.to_s) 2844: end
Delegates to id in order to allow two records of the same type and id to work with something like:
[ Person.find(1), Person.find(2), Person.find(3) ] & [ Person.find(1), Person.find(4) ] # => [ Person.find(1) ]
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# File activerecord/lib/active_record/base.rb, line 2871 2871: def hash 2872: id.hash 2873: end
A model instance‘s primary key is always available as model.id whether you name it the default ‘id’ or set it to something else.
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# File activerecord/lib/active_record/base.rb, line 2490 2490: def id 2491: attr_name = self.class.primary_key 2492: column = column_for_attribute(attr_name) 2493: 2494: self.class.send(:define_read_method, :id, attr_name, column) 2495: # now that the method exists, call it 2496: self.send attr_name.to_sym 2497: 2498: end
Sets the primary ID.
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# File activerecord/lib/active_record/base.rb, line 2554 2554: def id=(value) 2555: write_attribute(self.class.primary_key, value) 2556: end
Initializes attribute to zero if nil and adds the value passed as by (default is 1). The increment is performed directly on the underlying attribute, no setter is invoked. Only makes sense for number-based attributes. Returns self.
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# File activerecord/lib/active_record/base.rb, line 2692 2692: def increment(attribute, by = 1) 2693: self[attribute] ||= 0 2694: self[attribute] += by 2695: self 2696: end
Wrapper around increment that saves the record. This method differs from its non-bang version in that it passes through the attribute setter. Saving is not subjected to validation checks. Returns true if the record could be saved.
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# File activerecord/lib/active_record/base.rb, line 2702 2702: def increment!(attribute, by = 1) 2703: increment(attribute, by).update_attribute(attribute, self[attribute]) 2704: end
Returns the contents of the record as a nicely formatted string.
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# File activerecord/lib/active_record/base.rb, line 2902 2902: def inspect 2903: attributes_as_nice_string = self.class.column_names.collect { |name| 2904: if has_attribute?(name) || new_record? 2905: "#{name}: #{attribute_for_inspect(name)}" 2906: end 2907: }.compact.join(", ") 2908: "#<#{self.class} #{attributes_as_nice_string}>" 2909: end
Returns true if this object hasn‘t been saved yet — that is, a record for the object doesn‘t exist yet; otherwise, returns false.
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# File activerecord/lib/active_record/base.rb, line 2559 2559: def new_record? 2560: @new_record || false 2561: end
Marks this record as read only.
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# File activerecord/lib/active_record/base.rb, line 2897 2897: def readonly! 2898: @readonly = true 2899: end
Returns true if the record is read only. Records loaded through joins with piggy-back attributes will be marked as read only since they cannot be saved.
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# File activerecord/lib/active_record/base.rb, line 2892 2892: def readonly? 2893: defined?(@readonly) && @readonly == true 2894: end
Reloads the attributes of this object from the database. The optional options argument is passed to find when reloading so you may do e.g. record.reload(:lock => true) to reload the same record with an exclusive row lock.
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# File activerecord/lib/active_record/base.rb, line 2744 2744: def reload(options = nil) 2745: clear_aggregation_cache 2746: clear_association_cache 2747: @attributes.update(self.class.send(:with_exclusive_scope) { self.class.find(self.id, options) }.instance_variable_get('@attributes')) 2748: @attributes_cache = {} 2749: self 2750: end
Saves the model.
If the model is new a record gets created in the database, otherwise the existing record gets updated.
If perform_validation is true validations run. If any of them fail the action is cancelled and save returns false. If the flag is false validations are bypassed altogether. See ActiveRecord::Validations for more information.
There‘s a series of callbacks associated with save. If any of the before_* callbacks return false the action is cancelled and save returns false. See ActiveRecord::Callbacks for further details.
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# File activerecord/lib/active_record/base.rb, line 2580 2580: def save 2581: create_or_update 2582: end
Saves the model.
If the model is new a record gets created in the database, otherwise the existing record gets updated.
With save! validations always run. If any of them fail ActiveRecord::RecordInvalid gets raised. See ActiveRecord::Validations for more information.
There‘s a series of callbacks associated with save!. If any of the before_* callbacks return false the action is cancelled and save! raises ActiveRecord::RecordNotSaved. See ActiveRecord::Callbacks for further details.
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# File activerecord/lib/active_record/base.rb, line 2597 2597: def save! 2598: create_or_update || raise(RecordNotSaved) 2599: end
Returns a String, which Action Pack uses for constructing an URL to this object. The default implementation returns this record‘s id as a String, or nil if this record‘s unsaved.
For example, suppose that you have a User model, and that you have a map.resources :users route. Normally, user_path will construct a path with the user object‘s ‘id’ in it:
user = User.find_by_name('Phusion') user_path(user) # => "/users/1"
You can override to_param in your model to make user_path construct a path using the user‘s name instead of the user‘s id:
class User < ActiveRecord::Base def to_param # overridden name end end user = User.find_by_name('Phusion') user_path(user) # => "/users/Phusion"
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# File activerecord/lib/active_record/base.rb, line 2522 2522: def to_param 2523: # We can't use alias_method here, because method 'id' optimizes itself on the fly. 2524: (id = self.id) ? id.to_s : nil # Be sure to stringify the id for routes 2525: end
Assigns to attribute the boolean opposite of attribute?. So if the predicate returns true the attribute will become false. This method toggles directly the underlying value without calling any setter. Returns self.
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# File activerecord/lib/active_record/base.rb, line 2727 2727: def toggle(attribute) 2728: self[attribute] = !send("#{attribute}?") 2729: self 2730: end
Wrapper around toggle that saves the record. This method differs from its non-bang version in that it passes through the attribute setter. Saving is not subjected to validation checks. Returns true if the record could be saved.
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# File activerecord/lib/active_record/base.rb, line 2736 2736: def toggle!(attribute) 2737: toggle(attribute).update_attribute(attribute, self[attribute]) 2738: end
Updates a single attribute and saves the record without going through the normal validation procedure. This is especially useful for boolean flags on existing records. The regular update_attribute method in Base is replaced with this when the validations module is mixed in, which it is by default.
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# File activerecord/lib/active_record/base.rb, line 2663 2663: def update_attribute(name, value) 2664: send(name.to_s + '=', value) 2665: save(false) 2666: end
Updates all the attributes from the passed-in Hash and saves the record. If the object is invalid, the saving will fail and false will be returned.
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# File activerecord/lib/active_record/base.rb, line 2670 2670: def update_attributes(attributes) 2671: with_transaction_returning_status(:update_attributes_inside_transaction, attributes) 2672: end
Updates an object just like Base.update_attributes but calls save! instead of save so an exception is raised if the record is invalid.
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# File activerecord/lib/active_record/base.rb, line 2680 2680: def update_attributes!(attributes) 2681: with_transaction_returning_status(:update_attributes_inside_transaction!, attributes) 2682: end