aboutsummaryrefslogtreecommitdiffstats
path: root/activerecord/lib/active_record/autosave_association.rb
blob: f149d8f1270e7886bf1679df114c5f1b3fbe824c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
module ActiveRecord
  # = 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 <tt>marked_for_destruction?</tt>).
  #
  # 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 <tt>autosave: false</tt> is not same as not declaring <tt>:autosave</tt>.
  # When the <tt>:autosave</tt> option is not present then new association records are
  # saved but the updated association records are not saved.
  #
  # == Validation
  #
  # Children records are validated unless <tt>:validate</tt> 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 modifying the association content, before
  # autosave callbacks are executed. Placing your callbacks after
  # associations is usually a good practice.
  #
  # === One-to-one Example
  #
  #   class Post < ActiveRecord::Base
  #     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 <tt>:autosave</tt> is not declared new children are saved when their parent is saved:
  #
  #   class Post < ActiveRecord::Base
  #     has_many :comments # :autosave option is not 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 <tt>:autosave</tt> is true all children are saved, no matter whether they
  # are new records or not:
  #
  #   class Post < ActiveRecord::Base
  #     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.comments.build(body: "good morning.")
  #   post.title += "!"
  #   post.save # => saves both post and comments.
  #
  # Destroying one of the associated models as part of the parent's save action
  # is as simple as marking it for destruction:
  #
  #   post.comments # => [#<Comment id: 1, ...>, #<Comment id: 2, ...]>
  #   post.comments[1].mark_for_destruction
  #   post.comments[1].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

  module AutosaveAssociation
    extend ActiveSupport::Concern

    module AssociationBuilderExtension #:nodoc:
      def self.build(model, reflection)
        model.send(:add_autosave_association_callbacks, reflection)
      end

      def self.valid_options
        [ :autosave ]
      end
    end

    included do
      Associations::Builder::Association.extensions << AssociationBuilderExtension
    end

    module ClassMethods
      private

        def define_non_cyclic_method(name, &block)
          define_method(name) do |*args|
            result = true; @_already_called ||= {}
            # Loop prevention for validation of associations
            unless @_already_called[name]
              begin
                @_already_called[name]=true
                result = instance_eval(&block)
              ensure
                @_already_called[name]=false
              end
            end

            result
          end
        end

        # Adds validation and save callbacks for the association as specified by
        # the +reflection+.
        #
        # For performance reasons, we don't check whether to validate at runtime.
        # However the validation and callback methods are lazy and those methods
        # get created when they are invoked for the very first time. However,
        # this can change, for instance, when using nested attributes, which is
        # called _after_ the association has been defined. Since we don't want
        # the callbacks to get defined multiple times, there are guards that
        # check if the save or validation methods have already been defined
        # before actually defining them.
        def add_autosave_association_callbacks(reflection)
          save_method = :"autosave_associated_records_for_#{reflection.name}"
          validation_method = :"validate_associated_records_for_#{reflection.name}"
          collection = reflection.collection?

          unless method_defined?(save_method)
            if collection
              before_save :before_save_collection_association

              define_non_cyclic_method(save_method) { save_collection_association(reflection) }
              # Doesn't use after_save as that would save associations added in after_create/after_update twice
              after_create save_method
              after_update save_method
            elsif reflection.macro == :has_one
              define_method(save_method) { save_has_one_association(reflection) }
              # Configures two callbacks instead of a single after_save so that
              # the model may rely on their execution order relative to its
              # own callbacks.
              #
              # For example, given that after_creates run before after_saves, if
              # we configured instead an after_save there would be no way to fire
              # a custom after_create callback after the child association gets
              # created.
              after_create save_method
              after_update save_method
            else
              define_non_cyclic_method(save_method) { save_belongs_to_association(reflection) }
              before_save save_method
            end
          end

          if reflection.validate? && !method_defined?(validation_method)
            method = (collection ? :validate_collection_association : :validate_single_association)
            define_non_cyclic_method(validation_method) { send(method, reflection) }
            validate validation_method
          end
        end
    end

    # Reloads the attributes of the object as usual and clears <tt>marked_for_destruction</tt> flag.
    def reload(options = nil)
      @marked_for_destruction = false
      @destroyed_by_association = nil
      super
    end

    # 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 <tt>parent.save</tt> is called.
    #
    # Only useful if the <tt>:autosave</tt> option on the parent is enabled for this associated model.
    def mark_for_destruction
      @marked_for_destruction = true
    end

    # Returns whether or not this record will be destroyed as part of the parents save transaction.
    #
    # Only useful if the <tt>:autosave</tt> option on the parent is enabled for this associated model.
    def marked_for_destruction?
      @marked_for_destruction
    end

    # Records the association that is being destroyed and destroying this
    # record in the process.
    def destroyed_by_association=(reflection)
      @destroyed_by_association = reflection
    end

    # Returns the association for the parent being destroyed.
    #
    # Used to avoid updating the counter cache unnecessarily.
    def destroyed_by_association
      @destroyed_by_association
    end

    # Returns whether or not this record has been changed in any way (including whether
    # any of its nested autosave associations are likewise changed)
    def changed_for_autosave?
      new_record? || changed? || marked_for_destruction? || nested_records_changed_for_autosave?
    end

    private

      # 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.
      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

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

      # Validate the association if <tt>:validate</tt> or <tt>:autosave</tt> is
      # turned on for the association.
      def validate_single_association(reflection)
        association = association_instance_get(reflection.name)
        record      = association && association.reader
        association_valid?(reflection, record) if record
      end

      # Validate the associated records if <tt>:validate</tt> or
      # <tt>:autosave</tt> is turned on for the association specified by
      # +reflection+.
      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

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

      # 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.
      def before_save_collection_association
        @new_record_before_save = new_record?
        true
      end

      # Saves any new associated records, or all loaded autosave associations if
      # <tt>:autosave</tt> 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.
      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)

            if autosave
              records_to_destroy = records.select(&:marked_for_destruction?)
              records_to_destroy.each { |record| association.destroy(record) }
              records -= records_to_destroy
            end

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

              saved = true

              if 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
          end

          # reconstruct the scope now that we know the owner's id
          association.reset_scope if association.respond_to?(:reset_scope)
        end
      end

      # Saves the associated record if it's new or <tt>:autosave</tt> 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.
      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 && (autosave || new_record? || record_changed?(reflection, record, key))

              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

      # If the record is new or it has changed, returns true.
      def record_changed?(reflection, record, key)
        record.new_record? || record[reflection.foreign_key] != key || record.attribute_changed?(reflection.foreign_key)
      end

      # Saves the associated record if it's new or <tt>:autosave</tt> is enabled.
      #
      # In addition, it will destroy the association if it was marked for destruction.
      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?
            self[reflection.foreign_key] = nil
            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
  end
end