aboutsummaryrefslogtreecommitdiffstats
path: root/activerecord/lib/active_record/nested_attributes.rb
blob: 5778223c745025b69787165f24f83ef0df02ef49 (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
module ActiveRecord
  module NestedAttributes #:nodoc:
    def self.included(base)
      base.extend(ClassMethods)
      base.class_inheritable_accessor :reject_new_nested_attributes_procs, :instance_writer => false
      base.reject_new_nested_attributes_procs = {}
    end

    # == Nested Attributes
    #
    # Nested attributes allow you to save attributes on associated records
    # through the parent. By default nested attribute updating is turned off,
    # you can enable it using the accepts_nested_attributes_for class method.
    # When you enable nested attributes an attribute writer is defined on
    # the model.
    #
    # The attribute writer is named after the association, which means that
    # in the following example, two new methods are added to your model:
    # <tt>author_attributes=(attributes)</tt> and
    # <tt>pages_attributes=(attributes)</tt>.
    #
    #   class Book < ActiveRecord::Base
    #     has_one :author
    #     has_many :pages
    #
    #     accepts_nested_attributes_for :author, :pages
    #   end
    #
    # Note that the <tt>:autosave</tt> option is automatically enabled on every
    # association that accepts_nested_attributes_for is used for.
    #
    # === One-to-one
    #
    # Consider a Member model that has one Avatar:
    #
    #   class Member < ActiveRecord::Base
    #     has_one :avatar
    #     accepts_nested_attributes_for :avatar
    #   end
    #
    # Enabling nested attributes on a one-to-one association allows you to
    # create the member and avatar in one go:
    #
    #   params = { 'member' => { 'name' => 'Jack', 'avatar_attributes' => { 'icon' => 'smiling' } } }
    #   member = Member.create(params)
    #   member.avatar.icon #=> 'smiling'
    #
    # It also allows you to update the avatar through the member:
    #
    #   params = { 'member' => { 'avatar_attributes' => { 'icon' => 'sad' } } }
    #   member.update_attributes params['member']
    #   member.avatar.icon #=> 'sad'
    #
    # By default you will only be able to set and update attributes on the
    # associated model. If you want to destroy the associated model through the
    # attributes hash, you have to enable it first using the
    # <tt>:allow_destroy</tt> option.
    #
    #   class Member < ActiveRecord::Base
    #     has_one :avatar
    #     accepts_nested_attributes_for :avatar, :allow_destroy => true
    #   end
    #
    # Now, when you add the <tt>_delete</tt> key to the attributes hash, with a
    # value that evaluates to +true+, you will destroy the associated model:
    #
    #   member.avatar_attributes = { '_delete' => '1' }
    #   member.avatar.marked_for_destruction? # => true
    #   member.save
    #   member.avatar #=> nil
    #
    # Note that the model will _not_ be destroyed until the parent is saved.
    #
    # === One-to-many
    #
    # Consider a member that has a number of posts:
    #
    #   class Member < ActiveRecord::Base
    #     has_many :posts
    #     accepts_nested_attributes_for :posts, :reject_if => proc { |attributes| attributes['title'].blank? }
    #   end
    #
    # You can now set or update attributes on an associated post model through
    # the attribute hash.
    #
    # For each key in the hash that starts with the string 'new' a new model
    # will be instantiated. When the proc given with the <tt>:reject_if</tt>
    # option evaluates to +false+ for a certain attribute hash no record will
    # be built for that hash. (Rejecting new records can alternatively be done
    # by utilizing the <tt>'_delete'</tt> key. Scroll down for more info.)
    #
    #   params = { 'member' => {
    #     'name' => 'joe', 'posts_attributes' => {
    #       'new_12345' => { 'title' => 'Kari, the awesome Ruby documentation browser!' },
    #       'new_54321' => { 'title' => 'The egalitarian assumption of the modern citizen' },
    #       'new_67890' => { 'title' => '' } # This one matches the :reject_if proc and will not be instantiated.
    #     }
    #   }}
    #
    #   member = Member.create(params['member'])
    #   member.posts.length #=> 2
    #   member.posts.first.title #=> 'Kari, the awesome Ruby documentation browser!'
    #   member.posts.second.title #=> 'The egalitarian assumption of the modern citizen'
    #
    # When the key for post attributes is an integer, the associated post with
    # that ID will be updated:
    #
    #   member.attributes = {
    #     'name' => 'Joe',
    #     'posts_attributes' => {
    #       '1' => { 'title' => '[UPDATED] An, as of yet, undisclosed awesome Ruby documentation browser!' },
    #       '2' => { 'title' => '[UPDATED] other post' }
    #     }
    #   }
    #
    # By default the associated models are protected from being destroyed. If
    # you want to destroy any of the associated models through the attributes
    # hash, you have to enable it first using the <tt>:allow_destroy</tt>
    # option.
    #
    # This will allow you to specify which models to destroy in the attributes
    # hash by setting the '_delete' attribute to a value that evaluates to
    # +true+:
    #
    #   class Member < ActiveRecord::Base
    #     has_many :posts
    #     accepts_nested_attributes_for :posts, :allow_destroy => true
    #   end
    #
    #   params = {'member' => { 'name' => 'joe', 'posts_attributes' => {
    #     '2' => { '_delete' => '1' }
    #   }}}
    #   member.attributes = params['member']
    #   member.posts.detect { |p| p.id == 2 }.marked_for_destruction? # => true
    #   member.posts.length #=> 2
    #   member.save
    #   member.posts.length # => 1
    #
    # === Saving
    #
    # All changes to models, including the destruction of those marked for
    # destruction, are saved and destroyed automatically and atomically when
    # the parent model is saved. This happens inside the transaction initiated
    # by the parents save method. See ActiveRecord::AutosaveAssociation.
    module ClassMethods
      # Defines an attributes writer for the specified association(s).
      #
      # Supported options:
      # [:allow_destroy]
      #   If true, destroys any members from the attributes hash with a
      #   <tt>_delete</tt> key and a value that converts to +true+
      #   (eg. 1, '1', true, or 'true'). This option is off by default.
      # [:reject_if]
      #   Allows you to specify a Proc that checks whether a record should be
      #   built for a certain attribute hash. The hash is passed to the Proc
      #   and the Proc should return either +true+ or +false+. When no Proc
      #   is specified a record will be built for all attribute hashes.
      #
      # Examples:
      #   accepts_nested_attributes_for :avatar
      #   accepts_nested_attributes_for :avatar, :allow_destroy => true
      #   accepts_nested_attributes_for :avatar, :reject_if => proc { ... }
      #   accepts_nested_attributes_for :avatar, :posts, :allow_destroy => true, :reject_if => proc { ... }
      def accepts_nested_attributes_for(*attr_names)
        options = { :allow_destroy => false }
        options.update(attr_names.extract_options!)
        options.assert_valid_keys(:allow_destroy, :reject_if)

        attr_names.each do |association_name|
          if reflection = reflect_on_association(association_name)
            type = case reflection.macro
            when :has_one, :belongs_to
              :one_to_one
            when :has_many, :has_and_belongs_to_many
              :collection
            end

            reflection.options[:autosave] = true
            self.reject_new_nested_attributes_procs[association_name.to_sym] = options[:reject_if]

            # def pirate_attributes=(attributes)
            #   assign_nested_attributes_for_one_to_one_association(:pirate, attributes, false)
            # end
            class_eval %{
              def #{association_name}_attributes=(attributes)
                assign_nested_attributes_for_#{type}_association(:#{association_name}, attributes, #{options[:allow_destroy]})
              end
            }, __FILE__, __LINE__
          else
            raise ArgumentError, "No association found for name `#{association_name}'. Has it been defined yet?"
          end
        end
      end
    end

    # Returns ActiveRecord::AutosaveAssociation::marked_for_destruction?
    # It's used in conjunction with fields_for to build a form element
    # for the destruction of this association.
    #
    # See ActionView::Helpers::FormHelper::fields_for for more info.
    def _delete
      marked_for_destruction?
    end

    private

    # Assigns the given attributes to the association. An association will be
    # build if it doesn't exist yet.
    def assign_nested_attributes_for_one_to_one_association(association_name, attributes, allow_destroy)
      if should_destroy_nested_attributes_record?(allow_destroy, attributes)
        send(association_name).mark_for_destruction
      else
        (send(association_name) || send("build_#{association_name}")).attributes = attributes
      end
    end

    # Assigns the given attributes to the collection association.
    #
    # Keys containing an ID for an associated record will update that record.
    # Keys starting with <tt>new</tt> will instantiate a new record for that
    # association.
    #
    # For example:
    #
    #   assign_nested_attributes_for_collection_association(:people, {
    #     '1' => { 'name' => 'Peter' },
    #     'new_43' => { 'name' => 'John' }
    #   })
    #
    # Will update the name of the Person with ID 1 and create a new associated
    # person with the name 'John'.
    def assign_nested_attributes_for_collection_association(association_name, attributes, allow_destroy)
      unless attributes.is_a?(Hash)
        raise ArgumentError, "Hash expected, got #{attributes.class.name} (#{attributes.inspect})"
      end

      # Make sure any new records sorted by their id before they're build.
      sorted_by_id = attributes.sort_by { |id, _| id.is_a?(String) ? id.sub(/^new_/, '').to_i : id }

      sorted_by_id.each do |id, record_attributes|
        if id.acts_like?(:string) && id.starts_with?('new_')
          build_new_nested_attributes_record(association_name, record_attributes)
        else
          assign_to_or_destroy_nested_attributes_record(association_name, id, record_attributes, allow_destroy)
        end
      end
    end

    # Returns +true+ if <tt>allow_destroy</tt> is enabled and the attributes
    # contains a truthy value for the key <tt>'_delete'</tt>.
    #
    # It will _always_ remove the <tt>'_delete'</tt> key, if present.
    def should_destroy_nested_attributes_record?(allow_destroy, attributes)
      ConnectionAdapters::Column.value_to_boolean(attributes.delete('_delete')) && allow_destroy
    end

    # Builds a new record with the given attributes.
    #
    # If a <tt>:reject_if</tt> proc exists for this association, it will be
    # called with the attributes as its argument. If the proc returns a truthy
    # value, the record is _not_ build.
    #
    # Alternatively, you can specify the <tt>'_delete'</tt> key to _not_ build
    # a record. See should_destroy_nested_attributes_record? for more info.
    def build_new_nested_attributes_record(association_name, attributes)
      if reject_proc = self.class.reject_new_nested_attributes_procs[association_name]
        return if reject_proc.call(attributes)
      end
      send(association_name).build(attributes) unless should_destroy_nested_attributes_record?(true, attributes)
    end

    # Assigns the attributes to the record specified by +id+. Or marks it for
    # destruction if #should_destroy_nested_attributes_record? returns +true+.
    def assign_to_or_destroy_nested_attributes_record(association_name, id, attributes, allow_destroy)
      record = send(association_name).detect { |record| record.id == id.to_i }
      if should_destroy_nested_attributes_record?(allow_destroy, attributes)
        record.mark_for_destruction
      else
        record.attributes = attributes
      end
    end
  end
end