aboutsummaryrefslogtreecommitdiffstats
path: root/activerecord/lib/active_record/autosave_association.rb
blob: c1bc8423a9ad55bf16282615e445e213e3ea3f5a (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
module ActiveRecord
  # 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
  module AutosaveAssociation
    extend ActiveSupport::Concern

    ASSOCIATION_TYPES = %w{ has_one belongs_to has_many has_and_belongs_to_many }

    included do
      alias_method_chain :reload, :autosave_associations

      ASSOCIATION_TYPES.each do |type|
        send("valid_keys_for_#{type}_association") << :autosave
      end
    end

    module ClassMethods
      private

      # def belongs_to(name, options = {})
      #   super
      #   add_autosave_association_callbacks(reflect_on_association(name))
      # end
      ASSOCIATION_TYPES.each do |type|
        module_eval %{
          def #{type}(name, options = {})
            super
            add_autosave_association_callbacks(reflect_on_association(name))
          end
        }
      end

      # Adds a validate and save callback for the association as specified by
      # the +reflection+.
      def add_autosave_association_callbacks(reflection)
        save_method = "autosave_associated_records_for_#{reflection.name}"
        validation_method = "validate_associated_records_for_#{reflection.name}"
        validate validation_method

        case reflection.macro
        when :has_many, :has_and_belongs_to_many
          before_save :before_save_collection_association

          define_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

          define_method(validation_method) { validate_collection_association(reflection) }
        else
          case reflection.macro
          when :has_one
            define_method(save_method) { save_has_one_association(reflection) }
            after_save save_method
          when :belongs_to
            define_method(save_method) { save_belongs_to_association(reflection) }
            before_save save_method
          end
          define_method(validation_method) { validate_single_association(reflection) }
        end
      end
    end

    # Reloads the attributes of the object as usual and removes a mark for destruction.
    def reload_with_autosave_associations(options = nil)
      @marked_for_destruction = false
      reload_without_autosave_associations(options)
    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 <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

    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
      elsif association.loaded?
        autosave ? association : association.select { |record| record.new_record? }
      else
        autosave ? association.target : association.target.select { |record| record.new_record? }
      end
    end

    # Validate the association if <tt>:validate</tt> or <tt>:autosave</tt> is
    # turned on for the association specified by +reflection+.
    def validate_single_association(reflection)
      if reflection.options[:validate] == true || reflection.options[:autosave] == true
        if (association = association_instance_get(reflection.name)) && !association.target.nil?
          association_valid?(reflection, association)
        end
      end
    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 reflection.options[:validate] != false && 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?.
    def association_valid?(reflection, association)
      unless valid = association.valid?
        if reflection.options[:autosave]
          unless association.marked_for_destruction?
            association.errors.each do |attribute, message|
              attribute = "#{reflection.name}_#{attribute}"
              errors[attribute] << message if errors[attribute].empty?
            end
          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)
          records.each do |record|
            if autosave && record.marked_for_destruction?
              association.destroy(record)
            elsif @new_record_before_save || record.new_record?
              if autosave
                association.send(:insert_record, record, false, false)
              else
                association.send(:insert_record, record)
              end
            elsif autosave
              record.save(false)
            end
          end
        end

        # reconstruct the SQL queries now that we know the owner's id
        association.send(:construct_sql) if association.respond_to?(:construct_sql)
      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)
      if (association = association_instance_get(reflection.name)) && !association.target.nil?
        autosave = reflection.options[:autosave]

        if autosave && association.marked_for_destruction?
          association.destroy
        elsif new_record? || association.new_record? || association[reflection.primary_key_name] != id || autosave
          association[reflection.primary_key_name] = id
          association.save(!autosave)
        end
      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_belongs_to_association(reflection)
      if association = association_instance_get(reflection.name)
        autosave = reflection.options[:autosave]

        if autosave && association.marked_for_destruction?
          association.destroy
        else
          association.save(!autosave) if association.new_record? || autosave

          if association.updated?
            association_id = association.send(reflection.options[:primary_key] || :id)
            self[reflection.primary_key_name] = association_id
            # TODO: Removing this code doesn't seem to matter…
            if reflection.options[:polymorphic]
              self[reflection.options[:foreign_type]] = association.class.base_class.name.to_s
            end
          end
        end
      end
    end
  end
end