module ActiveRecord::AutosaveAssociation

Active Record Autosave Association

AutosaveAssociation is a module that takes care of automatically saving associated records when their parent is saved. In addition to saving, it also destroys any associated records that were marked for destruction. (See mark_for_destruction and marked_for_destruction?).

Saving of the parent, its associations, and the destruction of marked associations, all happen inside a transaction. This should never leave the database in an inconsistent state.

If validations for any of the associations fail, their error messages will be applied to the parent.

Note that it also means that associations marked for destruction won't be destroyed directly. They will however still be marked for destruction.

Note that :autosave => false is not same as not declaring :autosave. When the :autosave option is not present new associations are saved.

Validation

Children records are validated unless :validate is false.

Callbacks

Association with autosave option defines several callbacks on your model (before_save, after_create, after_update). Please note that callbacks are executed in the order they were defined in model. You should avoid modyfing the association content, before autosave callbacks are executed. Placing your callbacks after associations is usually a good practice.

Examples

One-to-one Example

class Post
  has_one :author, :autosave => true
end

Saving changes to the parent and its associated model can now be performed automatically and atomically:

post = Post.find(1)
post.title       # => "The current global position of migrating ducks"
post.author.name # => "alloy"

post.title = "On the migration of ducks"
post.author.name = "Eloy Duran"

post.save
post.reload
post.title       # => "On the migration of ducks"
post.author.name # => "Eloy Duran"

Destroying an associated model, as part of the parent's save action, is as simple as marking it for destruction:

post.author.mark_for_destruction
post.author.marked_for_destruction? # => true

Note that the model is not yet removed from the database:

id = post.author.id
Author.find_by_id(id).nil? # => false

post.save
post.reload.author # => nil

Now it is removed from the database:

Author.find_by_id(id).nil? # => true

One-to-many Example

When :autosave is not declared new children are saved when their parent is saved:

class Post
  has_many :comments # :autosave option is no declared
end

post = Post.new(:title => 'ruby rocks')
post.comments.build(:body => 'hello world')
post.save # => saves both post and comment

post = Post.create(:title => 'ruby rocks')
post.comments.build(:body => 'hello world')
post.save # => saves both post and comment

post = Post.create(:title => 'ruby rocks')
post.comments.create(:body => 'hello world')
post.save # => saves both post and comment

When :autosave is true all children is saved, no matter whether they are new records:

class Post
  has_many :comments, :autosave => true
end

post = Post.create(:title => 'ruby rocks')
post.comments.create(:body => 'hello world')
post.comments[0].body = 'hi everyone'
post.save # => saves both post and comment, with 'hi everyone' as body

Destroying one of the associated models as part of the parent's save action is as simple as marking it for destruction:

post.comments.last.mark_for_destruction
post.comments.last.marked_for_destruction? # => true
post.comments.length # => 2

Note that the model is not yet removed from the database:

id = post.comments.last.id
Comment.find_by_id(id).nil? # => false

post.save
post.reload.comments.length # => 1

Now it is removed from the database:

Comment.find_by_id(id).nil? # => true

Constants

ASSOCIATION_TYPES

Public Instance Methods

changed_for_autosave?() click to toggle source

Returns whether or not this record has been changed in any way (including whether any of its nested autosave associations are likewise changed)

# File lib/active_record/autosave_association.rb, line 247
def changed_for_autosave?
  new_record? || changed? || marked_for_destruction? || nested_records_changed_for_autosave?
end
mark_for_destruction() click to toggle source

Marks this record to be destroyed as part of the parents save transaction. This does not actually destroy the record instantly, rather child record will be destroyed when parent.save is called.

Only useful if the :autosave option on the parent is enabled for this associated model.

# File lib/active_record/autosave_association.rb, line 234
def mark_for_destruction
  @marked_for_destruction = true
end
marked_for_destruction?() click to toggle source

Returns whether or not this record will be destroyed as part of the parents save transaction.

Only useful if the :autosave option on the parent is enabled for this associated model.

# File lib/active_record/autosave_association.rb, line 241
def marked_for_destruction?
  @marked_for_destruction
end
reload(options = nil) click to toggle source

Reloads the attributes of the object as usual and clears marked_for_destruction flag.

Calls superclass method
# File lib/active_record/autosave_association.rb, line 224
def reload(options = nil)
  @marked_for_destruction = false
  super
end

Private Instance Methods

associated_records_to_validate_or_save(association, new_record, autosave) click to toggle source

Returns the record for an association collection that should be validated or saved. If autosave is false only new records will be returned, unless the parent is/was a new record itself.

# File lib/active_record/autosave_association.rb, line 256
def associated_records_to_validate_or_save(association, new_record, autosave)
  if new_record
    association && association.target
  elsif autosave
    association.target.find_all { |record| record.changed_for_autosave? }
  else
    association.target.find_all { |record| record.new_record? }
  end
end
association_valid?(reflection, record) click to toggle source

Returns whether or not the association is valid and applies any errors to the parent, self, if it wasn't. Skips any :autosave enabled records if they're marked_for_destruction? or destroyed.

# File lib/active_record/autosave_association.rb, line 297
def association_valid?(reflection, record)
  return true if record.destroyed? || record.marked_for_destruction?

  unless valid = record.valid?
    if reflection.options[:autosave]
      record.errors.each do |attribute, message|
        attribute = "#{reflection.name}.#{attribute}"
        errors[attribute] << message
        errors[attribute].uniq!
      end
    else
      errors.add(reflection.name)
    end
  end
  valid
end
before_save_collection_association() click to toggle source

Is used as a before_save callback to check while saving a collection association whether or not the parent was a new record before saving.

# File lib/active_record/autosave_association.rb, line 316
def before_save_collection_association
  @new_record_before_save = new_record?
  true
end
nested_records_changed_for_autosave?() click to toggle source

go through nested autosave associations that are loaded in memory (without loading any new ones), and return true if is changed for autosave

# File lib/active_record/autosave_association.rb, line 268
def nested_records_changed_for_autosave?
  self.class.reflect_on_all_autosave_associations.any? do |reflection|
    association = association_instance_get(reflection.name)
    association && Array.wrap(association.target).any? { |a| a.changed_for_autosave? }
  end
end
save_belongs_to_association(reflection) click to toggle source

Saves the associated record if it's new or :autosave is enabled.

In addition, it will destroy the association if it was marked for destruction.

# File lib/active_record/autosave_association.rb, line 406
def save_belongs_to_association(reflection)
  association = association_instance_get(reflection.name)
  record      = association && association.load_target
  if record && !record.destroyed?
    autosave = reflection.options[:autosave]

    if autosave && record.marked_for_destruction?
      record.destroy
    elsif autosave != false
      saved = record.save(:validate => !autosave) if record.new_record? || (autosave && record.changed_for_autosave?)

      if association.updated?
        association_id = record.send(reflection.options[:primary_key] || :id)
        self[reflection.foreign_key] = association_id
        association.loaded!
      end

      saved if autosave
    end
  end
end
save_collection_association(reflection) click to toggle source

Saves any new associated records, or all loaded autosave associations if :autosave is enabled on the association.

In addition, it destroys all children that were marked for destruction with mark_for_destruction.

This all happens inside a transaction, if the Transactions module is included into ActiveRecord::Base after the AutosaveAssociation module, which it does by default.

# File lib/active_record/autosave_association.rb, line 329
def save_collection_association(reflection)
  if association = association_instance_get(reflection.name)
    autosave = reflection.options[:autosave]

    if records = associated_records_to_validate_or_save(association, @new_record_before_save, autosave)
      begin
        records_to_destroy = []

        records.each do |record|
          next if record.destroyed?

          saved = true

          if autosave && record.marked_for_destruction?
            records_to_destroy << record
          elsif autosave != false && (@new_record_before_save || record.new_record?)
            if autosave
              saved = association.insert_record(record, false)
            else
              association.insert_record(record) unless reflection.nested?
            end
          elsif autosave
            saved = record.save(:validate => false)
          end

          raise ActiveRecord::Rollback unless saved
        end

        records_to_destroy.each do |record|
          association.proxy.destroy(record)
        end
      rescue
        records.each {|x| IdentityMap.remove(x) } if IdentityMap.enabled?
        raise
      end

    end

    # reconstruct the scope now that we know the owner's id
    association.send(:reset_scope) if association.respond_to?(:reset_scope)
  end
end
save_has_one_association(reflection) click to toggle source

Saves the associated record if it's new or :autosave is enabled on the association.

In addition, it will destroy the association if it was marked for destruction with mark_for_destruction.

This all happens inside a transaction, if the Transactions module is included into ActiveRecord::Base after the AutosaveAssociation module, which it does by default.

# File lib/active_record/autosave_association.rb, line 380
def save_has_one_association(reflection)
  association = association_instance_get(reflection.name)
  record      = association && association.load_target
  if record && !record.destroyed?
    autosave = reflection.options[:autosave]

    if autosave && record.marked_for_destruction?
      record.destroy
    else
      key = reflection.options[:primary_key] ? send(reflection.options[:primary_key]) : id
      if autosave != false && (new_record? || record.new_record? || record[reflection.foreign_key] != key || autosave)
        unless reflection.through_reflection
          record[reflection.foreign_key] = key
        end

        saved = record.save(:validate => !autosave)
        raise ActiveRecord::Rollback if !saved && autosave
        saved
      end
    end
  end
end
validate_collection_association(reflection) click to toggle source

Validate the associated records if :validate or :autosave is turned on for the association specified by reflection.

# File lib/active_record/autosave_association.rb, line 286
def validate_collection_association(reflection)
  if association = association_instance_get(reflection.name)
    if records = associated_records_to_validate_or_save(association, new_record?, reflection.options[:autosave])
      records.each { |record| association_valid?(reflection, record) }
    end
  end
end
validate_single_association(reflection) click to toggle source

Validate the association if :validate or :autosave is turned on for the association.

# File lib/active_record/autosave_association.rb, line 277
def validate_single_association(reflection)
  association = association_instance_get(reflection.name)
  record      = association && association.reader
  association_valid?(reflection, record) if record
end