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ActiveRecord::AutosaveAssociation

Active Record Autosave Association

AutosaveAssociation is a module that takes care of automatically saving associacted 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.

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 title

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

Validation

Children records are validated unless :validate is false.

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 210
210:     def changed_for_autosave?
211:       new_record? || changed? || marked_for_destruction? || nested_records_changed_for_autosave?
212:     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 197
197:     def mark_for_destruction
198:       @marked_for_destruction = true
199:     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 204
204:     def marked_for_destruction?
205:       @marked_for_destruction
206:     end
reload(options = nil) click to toggle source

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

     # File lib/active_record/autosave_association.rb, line 187
187:     def reload(options = nil)
188:       @marked_for_destruction = false
189:       super
190:     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 219
219:     def associated_records_to_validate_or_save(association, new_record, autosave)
220:       if new_record
221:         association
222:       elsif autosave
223:         association.target.find_all { |record| record.changed_for_autosave? }
224:       else
225:         association.target.find_all { |record| record.new_record? }
226:       end
227:     end
association_valid?(reflection, association) 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 260
260:     def association_valid?(reflection, association)
261:       return true if association.destroyed? || association.marked_for_destruction?
262: 
263:       unless valid = association.valid?
264:         if reflection.options[:autosave]
265:           association.errors.each do |attribute, message|
266:             attribute = "#{reflection.name}.#{attribute}"
267:             errors[attribute] << message
268:             errors[attribute].uniq!
269:           end
270:         else
271:           errors.add(reflection.name)
272:         end
273:       end
274:       valid
275:     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 279
279:     def before_save_collection_association
280:       @new_record_before_save = new_record?
281:       true
282:     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 231
231:     def nested_records_changed_for_autosave?
232:       self.class.reflect_on_all_autosave_associations.any? do |reflection|
233:         association = association_instance_get(reflection.name)
234:         association && Array.wrap(association.target).any? { |a| a.changed_for_autosave? }
235:       end
236:     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 350
350:     def save_belongs_to_association(reflection)
351:       if (association = association_instance_get(reflection.name)) && !association.destroyed?
352:         autosave = reflection.options[:autosave]
353: 
354:         if autosave && association.marked_for_destruction?
355:           association.destroy
356:         elsif autosave != false
357:           saved = association.save(:validate => !autosave) if association.new_record? || autosave
358: 
359:           if association.updated?
360:             association_id = association.send(reflection.options[:primary_key] || :id)
361:             self[reflection.primary_key_name] = association_id
362:           end
363: 
364:           saved if autosave
365:         end
366:       end
367:     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 292
292:     def save_collection_association(reflection)
293:       if association = association_instance_get(reflection.name)
294:         autosave = reflection.options[:autosave]
295: 
296:         if records = associated_records_to_validate_or_save(association, @new_record_before_save, autosave)
297:           records.each do |record|
298:             next if record.destroyed?
299: 
300:             if autosave && record.marked_for_destruction?
301:               association.destroy(record)
302:             elsif autosave != false && (@new_record_before_save || record.new_record?)
303:               if autosave
304:                 saved = association.send(:insert_record, record, false, false)
305:               else
306:                 association.send(:insert_record, record)
307:               end
308:             elsif autosave
309:               saved = record.save(:validate => false)
310:             end
311: 
312:             raise ActiveRecord::Rollback if saved == false
313:           end
314:         end
315: 
316:         # reconstruct the SQL queries now that we know the owner's id
317:         association.send(:construct_sql) if association.respond_to?(:construct_sql)
318:       end
319:     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 329
329:     def save_has_one_association(reflection)
330:       if (association = association_instance_get(reflection.name)) && !association.target.nil? && !association.destroyed?
331:         autosave = reflection.options[:autosave]
332: 
333:         if autosave && association.marked_for_destruction?
334:           association.destroy
335:         else
336:           key = reflection.options[:primary_key] ? send(reflection.options[:primary_key]) : id
337:           if autosave != false && (new_record? || association.new_record? || association[reflection.primary_key_name] != key || autosave)
338:             association[reflection.primary_key_name] = key
339:             saved = association.save(:validate => !autosave)
340:             raise ActiveRecord::Rollback if !saved && autosave
341:             saved
342:           end
343:         end
344:       end
345:     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 249
249:     def validate_collection_association(reflection)
250:       if association = association_instance_get(reflection.name)
251:         if records = associated_records_to_validate_or_save(association, new_record?, reflection.options[:autosave])
252:           records.each { |record| association_valid?(reflection, record) }
253:         end
254:       end
255:     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 240
240:     def validate_single_association(reflection)
241:       if (association = association_instance_get(reflection.name)) && !association.target.nil?
242:         association_valid?(reflection, association)
243:       end
244:     end

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