Active Record Persistence

Namespace
Methods
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Instance Public methods
becomes(klass)

Returns an instance of the specified klasswith 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 < Companyto 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.

# File activerecord/lib/active_record/persistence.rb, line 158
def becomes(klass)
  became = klass.new
  became.instance_variable_set("@attributes", @attributes)
  became.instance_variable_set("@attributes_cache", @attributes_cache)
  became.instance_variable_set("@new_record", new_record?)
  became.instance_variable_set("@destroyed", destroyed?)
  became.instance_variable_set("@errors", errors)
  became.send("#{klass.inheritance_column}=", klass.name) unless self.class.descends_from_active_record?
  became
end
decrement(attribute, by = 1)

Initializes attributeto zero if niland 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.

# File activerecord/lib/active_record/persistence.rb, line 252
def decrement(attribute, by = 1)
  self[attribute] ||= 0
  self[attribute] -= by
  self
end
decrement!(attribute, by = 1)

Wrapper around decrementthat 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 trueif the record could be saved.

# File activerecord/lib/active_record/persistence.rb, line 262
def decrement!(attribute, by = 1)
  decrement(attribute, by).update_attribute(attribute, self[attribute])
end
delete()

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 DELETEstatement on the record's primary key, and no callbacks are executed.

To enforce the object's before_destroyand after_destroycallbacks, Observer methods, or any :dependentassociation options, use #destroy.

# File activerecord/lib/active_record/persistence.rb, line 117
def delete
  if persisted?
    self.class.delete(id)
    IdentityMap.remove(self) if IdentityMap.enabled?
  end
  @destroyed = true
  freeze
end
destroy()

Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can't be persisted).

# File activerecord/lib/active_record/persistence.rb, line 128
def destroy
  destroy_associations

  if persisted?
    IdentityMap.remove(self) if IdentityMap.enabled?
    pk         = self.class.primary_key
    column     = self.class.columns_hash[pk]
    substitute = connection.substitute_at(column, 0)

    relation = self.class.unscoped.where(
      self.class.arel_table[pk].eq(substitute))

    relation.bind_values = [[column, id]]
    relation.delete_all
  end

  @destroyed = true
  freeze
end
destroyed?()

Returns true if this object has been destroyed, otherwise returns false.

# File activerecord/lib/active_record/persistence.rb, line 58
def destroyed?
  @destroyed
end
increment(attribute, by = 1)

Initializes attributeto zero if niland 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.

# File activerecord/lib/active_record/persistence.rb, line 235
def increment(attribute, by = 1)
  self[attribute] ||= 0
  self[attribute] += by
  self
end
increment!(attribute, by = 1)

Wrapper around incrementthat 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 trueif the record could be saved.

# File activerecord/lib/active_record/persistence.rb, line 245
def increment!(attribute, by = 1)
  increment(attribute, by).update_attribute(attribute, self[attribute])
end
new_record?()

Returns true if this object hasn't been saved yet – that is, a record for the object doesn't exist in the data store yet; otherwise, returns false.

# File activerecord/lib/active_record/persistence.rb, line 53
def new_record?
  @new_record
end
persisted?()

Returns if the record is persisted, i.e. it's not a new record and it was not destroyed.

# File activerecord/lib/active_record/persistence.rb, line 64
def persisted?
  !(new_record? || destroyed?)
end
reload(options = nil)

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.

# File activerecord/lib/active_record/persistence.rb, line 287
def reload(options = nil)
  clear_aggregation_cache
  clear_association_cache

  IdentityMap.without do
    fresh_object = self.class.unscoped { self.class.find(self.id, options) }
    @attributes.update(fresh_object.instance_variable_get('@attributes'))
  end

  @attributes_cache = {}
  self
end
save(*)

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 run validations. If any of them fail the action is cancelled and savereturns false. However, if you supply :validate => 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 falsethe action is cancelled and savereturns false. See ActiveRecord::Callbacks for further details.

# File activerecord/lib/active_record/persistence.rb, line 82
def save(*)
  begin
    create_or_update
  rescue ActiveRecord::RecordInvalid
    false
  end
end
save!(*)

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 falsethe action is cancelled and save!raises ActiveRecord::RecordNotSaved. See ActiveRecord::Callbacks for further details.

# File activerecord/lib/active_record/persistence.rb, line 103
def save!(*)
  create_or_update || raise(RecordNotSaved)
end
toggle(attribute)

Assigns to attributethe boolean opposite of attribute?. So if the predicate returns truethe attribute will become false. This method toggles directly the underlying value without calling any setter. Returns self.

# File activerecord/lib/active_record/persistence.rb, line 270
def toggle(attribute)
  self[attribute] = !send("#{attribute}?")
  self
end
toggle!(attribute)

Wrapper around togglethat 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 trueif the record could be saved.

# File activerecord/lib/active_record/persistence.rb, line 279
def toggle!(attribute)
  toggle(attribute).update_attribute(attribute, self[attribute])
end
touch(name = nil)

Saves the record with the updated_at/on attributes set to the current time. Please note that no validation is performed and no callbacks are executed. If an attribute name is passed, that attribute is updated along with updated_at/on attributes.

product.touch               # updates updated_at/on
product.touch(:designed_at) # updates the designed_at attribute and updated_at/on

If used along with belongs_tothen touchwill invoke touchmethod 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
# File activerecord/lib/active_record/persistence.rb, line 320
def touch(name = nil)
  attributes = timestamp_attributes_for_update_in_model
  attributes << name if name

  unless attributes.empty?
    current_time = current_time_from_proper_timezone
    changes = {}

    attributes.each do |column|
      changes[column.to_s] = write_attribute(column.to_s, current_time)
    end

    changes[self.class.locking_column] = increment_lock if locking_enabled?

    @changed_attributes.except!(*changes.keys)
    primary_key = self.class.primary_key
    self.class.unscoped.update_all(changes, { primary_key => self[primary_key] }) == 1
  end
end
update_attribute(name, value)

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.

# File activerecord/lib/active_record/persistence.rb, line 177
def update_attribute(name, value)
  name = name.to_s
  raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name)
  send("#{name}=", value)
  save(:validate => false)
end
update_attributes(attributes, options = {})

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.

When updating model attributes, mass-assignment security protection is respected. If no :asoption is supplied then the :defaultrole will be used. If you want to bypass the protection given by attr_protectedand attr_accessiblethen you can do so using the :without_protectionoption.

# File activerecord/lib/active_record/persistence.rb, line 212
def update_attributes(attributes, options = {})
  # 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
    self.assign_attributes(attributes, options)
    save
  end
end
update_attributes!(attributes, options = {})

Updates its receiver just like update_attributesbut calls save!instead of save, so an exception is raised if the record is invalid.

# File activerecord/lib/active_record/persistence.rb, line 223
def update_attributes!(attributes, options = {})
  # 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
    self.assign_attributes(attributes, options)
    save!
  end
end
update_column(name, value)

Updates a single attribute of an object, without calling save.

  • Validation is skipped.

  • Callbacks are skipped.

  • updated_at/updated_on column is not updated if that column is available.

Raises an ActiveRecordErrorwhen called on new objects, or when the nameattribute is marked as readonly.

# File activerecord/lib/active_record/persistence.rb, line 192
def update_column(name, value)
  name = name.to_s
  raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name)
  raise ActiveRecordError, "can not update on a new record object" unless persisted?

  updated_count = self.class.unscoped.update_all({ name => value }, self.class.primary_key => id)

  raw_write_attribute(name, value)

  updated_count == 1
end