module ActiveRecord::Persistence

Active Record Persistence

Public Instance Methods

becomes(klass) click to toggle source

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.

# File lib/active_record/persistence.rb, line 198
def becomes(klass)
  became = klass.new
  became.instance_variable_set("@attributes", @attributes)
  changed_attributes = @changed_attributes if defined?(@changed_attributes)
  became.instance_variable_set("@changed_attributes", changed_attributes || {})
  became.instance_variable_set("@new_record", new_record?)
  became.instance_variable_set("@destroyed", destroyed?)
  became.instance_variable_set("@errors", errors)
  became
end
becomes!(klass) click to toggle source

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.

# File lib/active_record/persistence.rb, line 215
def becomes!(klass)
  became = becomes(klass)
  sti_type = nil
  if !klass.descends_from_active_record?
    sti_type = klass.sti_name
  end
  became.public_send("#{klass.inheritance_column}=", sti_type)
  became
end
decrement(attribute, by = 1) click to toggle source

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.

# File lib/active_record/persistence.rb, line 328
def decrement(attribute, by = 1)
  self[attribute] ||= 0
  self[attribute] -= by
  self
end
decrement!(attribute, by = 1) click to toggle source

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.

# File lib/active_record/persistence.rb, line 338
def decrement!(attribute, by = 1)
  decrement(attribute, by).update_attribute(attribute, self[attribute])
end
delete() click to toggle source

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.

To enforce the object's before_destroy and after_destroy callbacks or any :dependent association options, use #destroy.

# File lib/active_record/persistence.rb, line 155
def delete
  self.class.delete(id) if persisted?
  @destroyed = true
  freeze
end
destroy() click to toggle source

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 return false the action is cancelled and destroy returns false. See ActiveRecord::Callbacks for further details.

# File lib/active_record/persistence.rb, line 168
def destroy
  raise ReadOnlyRecord, "#{self.class} is marked as readonly" if readonly?
  destroy_associations
  self.class.connection.add_transaction_record(self)
  destroy_row if persisted?
  @destroyed = true
  freeze
end
destroy!() click to toggle source

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 return false the action is cancelled and destroy! raises ActiveRecord::RecordNotDestroyed. See ActiveRecord::Callbacks for further details.

# File lib/active_record/persistence.rb, line 184
def destroy!
  destroy || raise(RecordNotDestroyed.new("Failed to destroy the record", self))
end
destroyed?() click to toggle source

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

# File lib/active_record/persistence.rb, line 91
def destroyed?
  sync_with_transaction_state
  @destroyed
end
increment(attribute, by = 1) click to toggle source

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.

# File lib/active_record/persistence.rb, line 311
def increment(attribute, by = 1)
  self[attribute] ||= 0
  self[attribute] += by
  self
end
increment!(attribute, by = 1) click to toggle source

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.

# File lib/active_record/persistence.rb, line 321
def increment!(attribute, by = 1)
  increment(attribute, by).update_attribute(attribute, self[attribute])
end
new_record?() click to toggle source

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.

# File lib/active_record/persistence.rb, line 85
def new_record?
  sync_with_transaction_state
  @new_record
end
persisted?() click to toggle source

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

# File lib/active_record/persistence.rb, line 98
def persisted?
  !(new_record? || destroyed?)
end
reload(options = nil) click to toggle source

Reloads the record from the database.

This method finds 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 lib/active_record/persistence.rb, line 407
def reload(options = nil)
  clear_aggregation_cache
  clear_association_cache
  self.class.connection.clear_query_cache

  fresh_object =
    if options && options[:lock]
      self.class.unscoped { self.class.lock(options[:lock]).find(id) }
    else
      self.class.unscoped { self.class.find(id) }
    end

  @attributes = fresh_object.instance_variable_get('@attributes')
  @new_record = false
  self
end
save(*) click to toggle source

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 save returns 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 false 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.

# File lib/active_record/persistence.rb, line 119
def save(*)
  create_or_update
rescue ActiveRecord::RecordInvalid
  false
end
save!(*) click to toggle source

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.

Attributes marked as readonly are silently ignored if the record is being updated.

# File lib/active_record/persistence.rb, line 141
def save!(*)
  create_or_update || raise(RecordNotSaved.new("Failed to save the record", self))
end
toggle(attribute) click to toggle source

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.

# File lib/active_record/persistence.rb, line 346
def toggle(attribute)
  self[attribute] = !send("#{attribute}?")
  self
end
toggle!(attribute) click to toggle source

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.

# File lib/active_record/persistence.rb, line 355
def toggle!(attribute)
  toggle(attribute).update_attribute(attribute, self[attribute])
end
touch(*names) click to toggle source

Saves the record with the updated_at/on attributes set to the current time. Please note that no validation is performed and only the after_touch, after_commit and after_rollback callbacks are executed.

If attribute names are passed, they are 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
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 lib/active_record/persistence.rb, line 455
def touch(*names)
  raise ActiveRecordError, "cannot touch on a new record object" unless persisted?

  attributes = timestamp_attributes_for_update_in_model
  attributes.concat(names)

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

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

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

    clear_attribute_changes(changes.keys)
    primary_key = self.class.primary_key
    self.class.unscoped.where(primary_key => self[primary_key]).update_all(changes) == 1
  else
    true
  end
end
update(attributes) click to toggle source

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 lib/active_record/persistence.rb, line 247
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
Also aliased as: update_attributes
update!(attributes) click to toggle source

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

# File lib/active_record/persistence.rb, line 260
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
Also aliased as: update_attributes!
update_attribute(name, value) click to toggle source

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.

See also update_column.

# File lib/active_record/persistence.rb, line 237
def update_attribute(name, value)
  name = name.to_s
  verify_readonly_attribute(name)
  send("#{name}=", value)
  save(validate: false)
end
update_attributes(attributes)
Alias for: update
update_attributes!(attributes)
Alias for: update!
update_column(name, value) click to toggle source

Equivalent to update_columns(name => value).

# File lib/active_record/persistence.rb, line 272
def update_column(name, value)
  update_columns(name => value)
end
update_columns(attributes) click to toggle source

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:

This method raises an ActiveRecord::ActiveRecordError when called on new objects, or when at least one of the attributes is marked as readonly.

# File lib/active_record/persistence.rb, line 291
def update_columns(attributes)
  raise ActiveRecordError, "cannot update a new record" if new_record?
  raise ActiveRecordError, "cannot update a destroyed record" if destroyed?

  attributes.each_key do |key|
    verify_readonly_attribute(key.to_s)
  end

  updated_count = self.class.unscoped.where(self.class.primary_key => id).update_all(attributes)

  attributes.each do |k, v|
    raw_write_attribute(k, v)
  end

  updated_count == 1
end

Private Instance Methods

_create_record(attribute_names = self.attribute_names) click to toggle source

Creates a record with values matching those of the instance attributes and returns its id.

# File lib/active_record/persistence.rb, line 521
def _create_record(attribute_names = self.attribute_names)
  attributes_values = arel_attributes_with_values_for_create(attribute_names)

  new_id = self.class.unscoped.insert attributes_values
  self.id ||= new_id if self.class.primary_key

  @new_record = false
  id
end
_update_record(attribute_names = self.attribute_names) click to toggle source

Updates the associated record with values matching those of the instance attributes. Returns the number of affected rows.

# File lib/active_record/persistence.rb, line 510
def _update_record(attribute_names = self.attribute_names)
  attributes_values = arel_attributes_with_values_for_update(attribute_names)
  if attributes_values.empty?
    0
  else
    self.class.unscoped._update_record attributes_values, id, id_was
  end
end
create_or_update() click to toggle source
# File lib/active_record/persistence.rb, line 502
def create_or_update
  raise ReadOnlyRecord, "#{self.class} is marked as readonly" if readonly?
  result = new_record? ? _create_record : _update_record
  result != false
end
destroy_associations() click to toggle source

A hook to be overridden by association modules.

# File lib/active_record/persistence.rb, line 483
def destroy_associations
end
destroy_row() click to toggle source
# File lib/active_record/persistence.rb, line 486
def destroy_row
  relation_for_destroy.delete_all
end
relation_for_destroy() click to toggle source
# File lib/active_record/persistence.rb, line 490
def relation_for_destroy
  pk         = self.class.primary_key
  column     = self.class.columns_hash[pk]
  substitute = self.class.connection.substitute_at(column)

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

  relation.bind_values = [[column, id]]
  relation
end
verify_readonly_attribute(name) click to toggle source
# File lib/active_record/persistence.rb, line 531
def verify_readonly_attribute(name)
  raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name)
end