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Returns a hash where the keys are column names and the values are default values when instantiating the AR object for this table.
Returns an array of column names as strings.
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.
Defines the name of the table column which will store the class name on single-table inheritance situations.
The default inheritance column name is type
, which means
it's a reserved word inside Active Record. To be able to use
single-table inheritance with another column name, or to use the column
type
in your own model for something else, you can set
inheritance_column
:
self.inheritance_column = 'zoink'
Sets the value of #inheritance_column
Returns a quoted version of the table name, used to construct SQL statements.
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 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 down
drop_table :job_levels
end
end
# File activerecord/lib/active_record/model_schema.rb, line 295 def reset_column_information connection.clear_cache! undefine_attribute_methods connection.schema_cache.clear_table_cache!(table_name) @arel_engine = nil @column_names = nil @column_types = nil @content_columns = nil @default_attributes = nil @inheritance_column = nil unless defined?(@explicit_inheritance_column) && @explicit_inheritance_column @relation = nil initialize_find_by_cache 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, 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
self.sequence_name = "projectseq" # default would have been "project_seq"
end
Indicates whether the table associated with this class exists
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 set your own table name explicitly:
class Mouse < ActiveRecord::Base
self.table_name = "mice"
end
Alternatively, you can override the #table_name method to
define your own computation. (Possibly using super
to
manipulate the default table name.) Example:
class Post < ActiveRecord::Base
def self.table_name
"special_" + super
end
end
Post.table_name # => "special_posts"
Sets the table name explicitly. Example:
class Project < ActiveRecord::Base
self.table_name = "project"
end
You can also just define your own self.table_name
method; see
the documentation for ActiveRecord::Base#table_name.
# File activerecord/lib/active_record/model_schema.rb, line 138 def table_name=(value) value = value && value.to_s if defined?(@table_name) return if value == @table_name reset_column_information if connected? end @table_name = value @quoted_table_name = nil @arel_table = nil @sequence_name = nil unless defined?(@explicit_sequence_name) && @explicit_sequence_name @relation = Relation.create(self, arel_table) end