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
- changed_for_autosave?
- included
- mark_for_destruction
- marked_for_destruction?
- reload_with_autosave_associations
ASSOCIATION_TYPES | = | %w{ has_one belongs_to has_many has_and_belongs_to_many } |
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# File activerecord/lib/active_record/autosave_association.rb, line 130 130: def self.included(base) 131: base.class_eval do 132: base.extend(ClassMethods) 133: alias_method_chain :reload, :autosave_associations 134: 135: ASSOCIATION_TYPES.each do |type| 136: base.send("valid_keys_for_#{type}_association") << :autosave 137: end 138: end 139: end
Returns whether or not this record has been changed in any way (including whether any of its nested autosave associations are likewise changed)
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# File activerecord/lib/active_record/autosave_association.rb, line 222 222: def changed_for_autosave? 223: new_record? || changed? || marked_for_destruction? || nested_records_changed_for_autosave? 224: end
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.
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# File activerecord/lib/active_record/autosave_association.rb, line 209 209: def mark_for_destruction 210: @marked_for_destruction = true 211: end
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.
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# File activerecord/lib/active_record/autosave_association.rb, line 216 216: def marked_for_destruction? 217: @marked_for_destruction 218: end
Reloads the attributes of the object as usual and removes a mark for destruction.
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# File activerecord/lib/active_record/autosave_association.rb, line 200 200: def reload_with_autosave_associations(options = nil) 201: @marked_for_destruction = false 202: reload_without_autosave_associations(options) 203: end