Active Record Persistence
- B
- D
- I
- N
- P
- R
- S
- T
- U
Instance Public methods
becomes(klass) Link
Returns an instance of the specified klass
with the attributes of the current record. This is mostly useful in relation to single table inheritance (STI) 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. Therefore the STI column value will still be the same. Any change to the attributes on either instance will affect both instances. If you want to change the STI column as well, use becomes!
instead.
# File activerecord/lib/active_record/persistence.rb, line 712 def becomes(klass) became = klass.allocate became.send(:initialize) do |becoming| becoming.instance_variable_set(:@attributes, @attributes) becoming.instance_variable_set(:@mutations_from_database, @mutations_from_database ||= nil) becoming.instance_variable_set(:@new_record, new_record?) becoming.instance_variable_set(:@destroyed, destroyed?) becoming.errors.copy!(errors) end became end
becomes!(klass) Link
Wrapper around becomes
that also changes the instance's STI column value. This is especially useful if you want to persist the changed class in your database.
Note: The old instance's STI column value will be changed too, as both objects share the same set of attributes.
decrement(attribute, by = 1) Link
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
.
decrement!(attribute, by = 1, touch: nil) Link
Wrapper around decrement
that writes the update to the database. Only attribute
is updated; the record itself is not saved. This means that any other modified attributes will still be dirty. Validations
and callbacks are skipped. Supports the touch
option from update_counters
, see that for more. Returns self
.
delete() Link
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 an SQL DELETE
statement on the record's primary key, and no callbacks are executed.
Note that this will also delete records marked as #readonly?.
To enforce the object's before_destroy
and after_destroy
callbacks or any :dependent
association options, use destroy
.
destroy() Link
Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can't be persisted).
There's a series of callbacks associated with destroy
. If the before_destroy
callback throws :abort
the action is cancelled and destroy
returns false
. See ActiveRecord::Callbacks
for further details.
destroy!() Link
Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can't be persisted).
There's a series of callbacks associated with destroy!
. If the before_destroy
callback throws :abort
the action is cancelled and destroy!
raises ActiveRecord::RecordNotDestroyed
. See ActiveRecord::Callbacks
for further details.
destroyed?() Link
Returns true if this object has been destroyed, otherwise returns false.
increment(attribute, by = 1) Link
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
.
increment!(attribute, by = 1, touch: nil) Link
Wrapper around increment
that writes the update to the database. Only attribute
is updated; the record itself is not saved. This means that any other modified attributes will still be dirty. Validations
and callbacks are skipped. Supports the touch
option from update_counters
, see that for more. Returns self
.
# File activerecord/lib/active_record/persistence.rb, line 845 def increment!(attribute, by = 1, touch: nil) increment(attribute, by) change = public_send(attribute) - (public_send(:"#{attribute}_in_database") || 0) self.class.update_counters(id, attribute => change, touch: touch) public_send(:"clear_#{attribute}_change") self end
new_record?() Link
Returns true if this object hasn't been saved yet – that is, a record for the object doesn't exist in the database yet; otherwise, returns false.
persisted?() Link
Returns true if the record is persisted, i.e. it's not a new record and it was not destroyed, otherwise returns false.
previously_new_record?() Link
Returns true if this object was just created – that is, prior to the last save, the object didn't exist in the database and new_record? would have returned true.
previously_persisted?() Link
Returns true if this object was previously persisted but now it has been deleted.
reload(options = nil) Link
Reloads the record from the database.
This method finds the record by its primary key (which could be assigned manually) and modifies the receiver in-place:
account = Account.new
# => #<Account id: nil, email: nil>
account.id = 1
account.reload
# Account Load (1.2ms) SELECT "accounts".* FROM "accounts" WHERE "accounts"."id" = $1 LIMIT 1 [["id", 1]]
# => #<Account id: 1, email: 'account@example.com'>
Attributes
are reloaded from the database, and caches busted, in particular the associations cache and the QueryCache
.
If the record no longer exists in the database ActiveRecord::RecordNotFound
is raised. Otherwise, in addition to the in-place modification the method returns self
for convenience.
The optional :lock
flag option allows you to lock the reloaded record:
reload(lock: true) # reload with pessimistic locking
Reloading is commonly used in test suites to test something is actually written to the database, or when some action modifies the corresponding row in the database but not the object in memory:
assert account.deposit!(25)
assert_equal 25, account.credit # check it is updated in memory
assert_equal 25, account.reload.credit # check it is also persisted
Another common use case is optimistic locking handling:
def with_optimistic_retry
begin
yield
rescue ActiveRecord::StaleObjectError
begin
# Reload lock_version in particular.
reload
rescue ActiveRecord::RecordNotFound
# If the record is gone there is nothing to do.
else
retry
end
end
end
# File activerecord/lib/active_record/persistence.rb, line 943 def reload(options = nil) self.class.connection.clear_query_cache fresh_object = if apply_scoping?(options) _find_record(options) else self.class.unscoped { _find_record(options) } end @association_cache = fresh_object.instance_variable_get(:@association_cache) @attributes = fresh_object.instance_variable_get(:@attributes) @new_record = false @previously_new_record = false self end
save(**options) Link
Saves the model.
If the model is new, a record gets created in the database, otherwise the existing record gets updated.
By default, save always runs validations. If any of them fail the action is cancelled and save
returns false
, and the record won't be saved. However, if you supply validate: false
, validations are bypassed altogether. See ActiveRecord::Validations
for more information.
By default, save
also sets the updated_at
/updated_on
attributes to the current time. However, if you supply touch: false
, these timestamps will not be updated.
There's a series of callbacks associated with save
. If any of the before_*
callbacks throws :abort
the action is cancelled and save
returns false
. See ActiveRecord::Callbacks
for further details.
Attributes
marked as readonly are silently ignored if the record is being updated.
save!(**options) Link
Saves the model.
If the model is new, a record gets created in the database, otherwise the existing record gets updated.
By default, save!
always runs validations. If any of them fail ActiveRecord::RecordInvalid
gets raised, and the record won't be saved. However, if you supply validate: false
, validations are bypassed altogether. See ActiveRecord::Validations
for more information.
By default, save!
also sets the updated_at
/updated_on
attributes to the current time. However, if you supply touch: false
, these timestamps will not be updated.
There's a series of callbacks associated with save!
. If any of the before_*
callbacks throws :abort
the action is cancelled and save!
raises ActiveRecord::RecordNotSaved
. See ActiveRecord::Callbacks
for further details.
Attributes
marked as readonly are silently ignored if the record is being updated.
Unless an error is raised, returns true.
toggle(attribute) Link
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
.
Example:
user = User.first
user.banned? # => false
user.toggle(:banned)
user.banned? # => true
toggle!(attribute) Link
Wrapper around toggle
that saves the record. This method differs from its non-bang version in the sense that it passes through the attribute setter. Saving is not subjected to validation checks. Returns true
if the record could be saved.
touch(*names, time: nil) Link
Saves the record with the updated_at/on attributes set to the current time or the time specified. Please note that no validation is performed and only the after_touch
, after_commit
and after_rollback
callbacks are executed.
This method can be passed attribute names and an optional time argument. If attribute names are passed, they are updated along with updated_at/on attributes. If no time argument is passed, the current time is used as default.
product.touch # updates updated_at/on with current time
product.touch(time: Time.new(2015, 2, 16, 0, 0, 0)) # updates updated_at/on with specified time
product.touch(:designed_at) # updates the designed_at attribute and updated_at/on
product.touch(:started_at, :ended_at) # updates started_at, ended_at and updated_at/on attributes
If used along with belongs_to then touch
will invoke touch
method on associated object.
class Brake < ActiveRecord::Base
belongs_to :car, touch: true
end
class Car < ActiveRecord::Base
belongs_to :corporation, touch: true
end
# triggers @brake.car.touch and @brake.car.corporation.touch
@brake.touch
Note that touch
must be used on a persisted object, or else an ActiveRecordError
will be thrown. For example:
ball = Ball.new
ball.touch(:updated_at) # => raises ActiveRecordError
# File activerecord/lib/active_record/persistence.rb, line 993 def touch(*names, time: nil) _raise_record_not_touched_error unless persisted? attribute_names = timestamp_attributes_for_update_in_model attribute_names |= names.map! do |name| name = name.to_s self.class.attribute_aliases[name] || name end unless names.empty? unless attribute_names.empty? affected_rows = _touch_row(attribute_names, time) @_trigger_update_callback = affected_rows == 1 else true end end
update(attributes) Link
Updates the attributes of the model from the passed-in hash and saves the record, all wrapped in a transaction. If the object is invalid, the saving will fail and false will be returned.
# File activerecord/lib/active_record/persistence.rb, line 765 def update(attributes) # The following transaction covers any possible database side-effects of the # attributes assignment. For example, setting the IDs of a child collection. with_transaction_returning_status do assign_attributes(attributes) save end end
update!(attributes) Link
Updates its receiver just like update
but calls save!
instead of save
, so an exception is raised if the record is invalid and saving will fail.
# File activerecord/lib/active_record/persistence.rb, line 776 def update!(attributes) # The following transaction covers any possible database side-effects of the # attributes assignment. For example, setting the IDs of a child collection. with_transaction_returning_status do assign_attributes(attributes) save! end end
update_attribute(name, value) Link
Updates a single attribute and saves the record. This is especially useful for boolean flags on existing records. Also note that
-
Validation is skipped.
-
Callbacks are invoked.
-
updated_at/updated_on column is updated if that column is available.
-
Updates all the attributes that are dirty in this object.
This method raises an ActiveRecord::ActiveRecordError
if the attribute is marked as readonly.
Also see update_column
.
update_column(name, value) Link
Equivalent to update_columns(name => value)
.
update_columns(attributes) Link
Updates the attributes directly in the database issuing an UPDATE SQL statement and sets them in the receiver:
user.update_columns(last_request_at: Time.current)
This is the fastest way to update attributes because it goes straight to the database, but take into account that in consequence the regular update procedures are totally bypassed. In particular:
-
Validations are skipped.
-
Callbacks are skipped.
-
updated_at
/updated_on
are not updated. -
However, attributes are serialized with the same rules as
ActiveRecord::Relation#update_all
This method raises an ActiveRecord::ActiveRecordError
when called on new objects, or when at least one of the attributes is marked as readonly.
# File activerecord/lib/active_record/persistence.rb, line 806 def update_columns(attributes) raise ActiveRecordError, "cannot update a new record" if new_record? raise ActiveRecordError, "cannot update a destroyed record" if destroyed? attributes = attributes.transform_keys do |key| name = key.to_s name = self.class.attribute_aliases[name] || name verify_readonly_attribute(name) || name end update_constraints = _primary_key_constraints_hash attributes = attributes.each_with_object({}) do |(k, v), h| h[k] = @attributes.write_cast_value(k, v) clear_attribute_change(k) end affected_rows = self.class._update_record( attributes, update_constraints ) affected_rows == 1 end