Module: ActiveRecord::Persistence

Extended by:
ActiveSupport::Concern
Included in:
Base
Defined in:
lib/active_record/persistence.rb

Overview

Active Record Persistence

Defined Under Namespace

Modules: ClassMethods

Instance Method Summary collapse

Instance Method Details

#becomes(klass) ⇒ Object

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 'lib/active_record/persistence.rb', line 180

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
end

#becomes!(klass) ⇒ Object

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.


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# File 'lib/active_record/persistence.rb', line 196

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) ⇒ Object

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 'lib/active_record/persistence.rb', line 306

def decrement(attribute, by = 1)
  self[attribute] ||= 0
  self[attribute] -= by
  self
end

#decrement!(attribute, by = 1) ⇒ Object

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 'lib/active_record/persistence.rb', line 316

def decrement!(attribute, by = 1)
  decrement(attribute, by).update_attribute(attribute, self[attribute])
end

#deleteObject

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.


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# File 'lib/active_record/persistence.rb', line 138

def delete
  self.class.delete(id) if persisted?
  @destroyed = true
  freeze
end

#destroyObject

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.

Raises:


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# File 'lib/active_record/persistence.rb', line 151

def destroy
  raise ReadOnlyRecord if readonly?
  destroy_associations
  destroy_row if persisted?
  @destroyed = true
  freeze
end

#destroy!Object

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.


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# File 'lib/active_record/persistence.rb', line 166

def destroy!
  destroy || raise(ActiveRecord::RecordNotDestroyed)
end

#destroyed?Boolean

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

Returns:

  • (Boolean)

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# File 'lib/active_record/persistence.rb', line 74

def destroyed?
  sync_with_transaction_state
  @destroyed
end

#increment(attribute, by = 1) ⇒ Object

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 'lib/active_record/persistence.rb', line 289

def increment(attribute, by = 1)
  self[attribute] ||= 0
  self[attribute] += by
  self
end

#increment!(attribute, by = 1) ⇒ Object

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 'lib/active_record/persistence.rb', line 299

def increment!(attribute, by = 1)
  increment(attribute, by).update_attribute(attribute, self[attribute])
end

#new_record?Boolean

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.

Returns:

  • (Boolean)

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# File 'lib/active_record/persistence.rb', line 68

def new_record?
  sync_with_transaction_state
  @new_record
end

#persisted?Boolean

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

Returns:

  • (Boolean)

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# File 'lib/active_record/persistence.rb', line 81

def persisted?
  !(new_record? || destroyed?)
end

#reload(options = nil) ⇒ Object

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.new
# => #<Account id: nil, email: nil>
.id = 1
.reload
# Account Load (1.2ms)  SELECT "accounts".* FROM "accounts" WHERE "accounts"."id" = $1 LIMIT 1  [["id", 1]]
# => #<Account id: 1, email: '[email protected]'>

Attributes are updated, and caches busted, in particular the associations cache.

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 .deposit!(25)
assert_equal 25, .credit        # check it is updated in memory
assert_equal 25, .reload.credit # check it is also persisted

Another commom 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

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# File 'lib/active_record/persistence.rb', line 384

def reload(options = nil)
  clear_aggregation_cache
  clear_association_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.update(fresh_object.instance_variable_get('@attributes'))

  @column_types           = self.class.column_types
  @column_types_override  = fresh_object.instance_variable_get('@column_types_override')
  @attributes_cache       = {}
  self
end

#saveObject

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.


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# File 'lib/active_record/persistence.rb', line 102

def save(*)
  create_or_update
rescue ActiveRecord::RecordInvalid
  false
end

#save!Object

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.


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# File 'lib/active_record/persistence.rb', line 124

def save!(*)
  create_or_update || raise(RecordNotSaved)
end

#toggle(attribute) ⇒ Object

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 'lib/active_record/persistence.rb', line 324

def toggle(attribute)
  self[attribute] = !send("#{attribute}?")
  self
end

#toggle!(attribute) ⇒ Object

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 'lib/active_record/persistence.rb', line 333

def toggle!(attribute)
  toggle(attribute).update_attribute(attribute, self[attribute])
end

#touch(name = nil) ⇒ Object

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 callback is 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_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

Raises:


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# File 'lib/active_record/persistence.rb', line 431

def touch(name = nil)
  raise ActiveRecordError, "can not touch on a new record object" unless persisted?

  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|
      column = column.to_s
      changes[column] = write_attribute(column, 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.where(primary_key => self[primary_key]).update_all(changes) == 1
  end
end

#update(attributes) ⇒ Object Also known as: update_attributes

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.


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# File 'lib/active_record/persistence.rb', line 226

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) ⇒ Object Also known as: update_attributes!

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


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# File 'lib/active_record/persistence.rb', line 239

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) ⇒ Object

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.


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# File 'lib/active_record/persistence.rb', line 216

def update_attribute(name, value)
  name = name.to_s
  verify_readonly_attribute(name)
  send("#{name}=", value)
  save(validate: false)
end

#update_column(name, value) ⇒ Object

Equivalent to update_columns(name => value).


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# File 'lib/active_record/persistence.rb', line 251

def update_column(name, value)
  update_columns(name => value)
end

#update_columns(attributes) ⇒ Object

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.

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

Raises:


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# File 'lib/active_record/persistence.rb', line 270

def update_columns(attributes)
  raise ActiveRecordError, "can not update on a new record object" unless persisted?

  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