Module: ActiveRecord::AutosaveAssociation

Module | ActiveRecord::AutosaveAssociation
In: | lib/active_record/autosave_association.rb

AutosaveAssociation is a module that takes care of automatically saving your associations when the parent is saved. In addition to saving, it also destroys any associations 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 1 transaction. This should never leave the database in an inconsistent state after, for instance, mass assigning attributes and saving them.

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.

### One-to-one Example

Consider a Post model with one Author:

      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

Consider a Post model with many Comments:

      class Post
        has_many :comments, :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.comments.first.body # => "Wow, awesome info thanks!"
      post.comments.last.body # => "Actually, your article should be named differently."

      post.title = "On the migration of ducks"
      post.comments.last.body = "Actually, your article should be named differently. [UPDATED]: You are right, thanks."

      post.save
      post.reload
      post.title # => "On the migration of ducks"
      post.comments.last.body # => "Actually, your article should be named differently. [UPDATED]: You are right, thanks."

Destroying one of the associated models members, 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

### Validation

Validation is performed on the parent as usual, but also on all autosave enabled associations. If any of the associations fail validation, its error messages will be applied on the parents errors object and validation of the parent will fail.

Consider a Post model with Author which validates the presence of its name attribute:

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

      class Author
        validates_presence_of :name
      end

      post = Post.find(1)
      post.author.name = ''
      post.save # => false
      post.errors # => #<ActiveRecord::Errors:0x174498c @errors={"author_name"=>["can't be blank"]}, @base=#<Post ...>>

No validations will be performed on the associated models when validations are skipped for the parent:

      post = Post.find(1)
      post.author.name = ''
      post.save(false) # => true

### Methods

included mark_for_destruction marked_for_destruction? reload_with_autosave_associations

### Classes and Modules

Module ActiveRecord::AutosaveAssociation::ClassMethods

### Constants

ASSOCIATION_TYPES | = | %w{ has_one belongs_to has_many has_and_belongs_to_many }

### Public Class methods

included(base)

### Public Instance methods

mark_for_destruction()

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

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

marked_for_destruction?()

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.

reload_with_autosave_associations(options = nil)

Reloads the attributes of the object as usual and removes a mark for destruction.

[Validate]