aboutsummaryrefslogtreecommitdiffstats
path: root/activerecord/lib/active_record/association_preload.rb
blob: 0c31c85bb0178cf6fdc0fb1b8dc78698f0e07636 (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
module ActiveRecord
  module AssociationPreload #:nodoc:
    def self.included(base)
      base.extend(ClassMethods)
    end

    module ClassMethods

      # Loads the named associations for the activerecord record (or records) given
      # preload_options is passed only one level deep: don't pass to the child associations when associations is a Hash
      protected
      def preload_associations(records, associations, preload_options={})
        records = [records].flatten.compact.uniq
        return if records.empty?
        case associations
        when Array then associations.each {|association| preload_associations(records, association, preload_options)}
        when Symbol, String then preload_one_association(records, associations.to_sym, preload_options)
        when Hash then
          associations.each do |parent, child|
            raise "parent must be an association name" unless parent.is_a?(String) || parent.is_a?(Symbol)
            preload_associations(records, parent, preload_options)
            reflection = reflections[parent]
            parents = records.map {|record| record.send(reflection.name)}.flatten
            unless parents.empty? || parents.first.nil?
              parents.first.class.preload_associations(parents, child)
            end
          end
        end
      end

      private

      def preload_one_association(records, association, preload_options={})
        reflection = reflections[association]
        raise ConfigurationError, "Association named '#{ association }' was not found; perhaps you misspelled it?" unless reflection

        # Not all records have the same class, so group then preload.
        records.group_by(&:class).each do |klass, records|
          reflection = klass.reflections[association]
          send("preload_#{reflection.macro}_association", records, reflection, preload_options)
        end
      end

      def add_preloaded_records_to_collection(parent_records, reflection_name, associated_record)
        parent_records.each do |parent_record|
          association_proxy = parent_record.send(reflection_name)
          association_proxy.loaded
          association_proxy.target.push(*[associated_record].flatten)
        end
      end
      
      def add_preloaded_record_to_collection(parent_records, reflection_name, associated_record)
        parent_records.each do |parent_record|
          association_proxy = parent_record.send(reflection_name)
          association_proxy.loaded
          association_proxy.target = associated_record
        end
      end

      def set_association_collection_records(id_to_record_map, reflection_name, associated_records, key)
        associated_records.each do |associated_record|
          mapped_records = id_to_record_map[associated_record[key].to_i]
          add_preloaded_records_to_collection(mapped_records, reflection_name, associated_record)
        end
      end

      def set_association_single_records(id_to_record_map, reflection_name, associated_records, key)
        associated_records.each do |associated_record|
          mapped_records = id_to_record_map[associated_record[key].to_i]
          mapped_records.each do |mapped_record|
            mapped_record.send("set_#{reflection_name}_target", associated_record)
          end
        end
      end

      def construct_id_map(records)
        id_to_record_map = {}
        ids = []
        records.each do |record|
          ids << record.id
          mapped_records = (id_to_record_map[record.id] ||= [])
          mapped_records << record
        end
        ids.uniq!
        return id_to_record_map, ids
      end

      # FIXME: quoting
      def preload_has_and_belongs_to_many_association(records, reflection, preload_options={})
        table_name = reflection.klass.table_name
        id_to_record_map, ids = construct_id_map(records)
        records.each {|record| record.send(reflection.name).loaded}
        options = reflection.options

        conditions = "t0.#{reflection.primary_key_name}  IN (?)"
        conditions << append_conditions(options, preload_options)

        associated_records = reflection.klass.find(:all, :conditions => [conditions, ids],
        :include => options[:include],
        :joins => "INNER JOIN #{options[:join_table]} as t0 ON #{reflection.klass.table_name}.#{reflection.klass.primary_key} = t0.#{reflection.association_foreign_key}",
        :select => "#{options[:select] || table_name+'.*'}, t0.#{reflection.primary_key_name} as _parent_record_id",
        :order => options[:order])

        set_association_collection_records(id_to_record_map, reflection.name, associated_records, '_parent_record_id')
      end

      def preload_has_one_association(records, reflection, preload_options={})
        id_to_record_map, ids = construct_id_map(records)        
        options = reflection.options
        if options[:through]
          records.each {|record| record.send(reflection.name) && record.send(reflection.name).loaded}
          through_records = preload_through_records(records, reflection, options[:through])
          through_reflection = reflections[options[:through]]
          through_primary_key = through_reflection.primary_key_name
          unless through_records.empty?
            source = reflection.source_reflection.name
            through_records.first.class.preload_associations(through_records, source)
            through_records.compact.each do |through_record|
              add_preloaded_record_to_collection(id_to_record_map[through_record[through_primary_key].to_i],
                                                 reflection.name, through_record.send(source))
            end
          end          
        else          
          records.each {|record| record.send("set_#{reflection.name}_target", nil)}


          set_association_single_records(id_to_record_map, reflection.name, find_associated_records(ids, reflection, preload_options), reflection.primary_key_name)
        end                                       
      end

      def preload_has_many_association(records, reflection, preload_options={})
        id_to_record_map, ids = construct_id_map(records)
        records.each {|record| record.send(reflection.name).loaded}
        options = reflection.options

        if options[:through]
          through_records = preload_through_records(records, reflection, options[:through])
          through_reflection = reflections[options[:through]]
          through_primary_key = through_reflection.primary_key_name
          unless through_records.empty?
            source = reflection.source_reflection.name
            through_records.first.class.preload_associations(through_records, source)
            through_records.compact.each do |through_record|
              add_preloaded_records_to_collection(id_to_record_map[through_record[through_primary_key].to_i],
                                                 reflection.name, through_record.send(source))
            end
          end
        else
          set_association_collection_records(id_to_record_map, reflection.name, find_associated_records(ids, reflection, preload_options),
                                             reflection.primary_key_name)
        end
      end
      
      def preload_through_records(records, reflection, through_association)
        through_reflection = reflections[through_association]
        through_primary_key = through_reflection.primary_key_name

        if reflection.options[:source_type]
          interface = reflection.source_reflection.options[:foreign_type]
          preload_options = {:conditions => ["#{interface} = ?", reflection.options[:source_type]]}

          records.first.class.preload_associations(records, through_association, preload_options)

          # Dont cache the association - we would only be caching a subset
          through_records = []
          records.compact.each do |record|
            proxy = record.send(through_association)
            through_records << proxy.target
            proxy.reset
          end
          through_records = through_records.flatten
        else
          records.first.class.preload_associations(records, through_association)
          through_records = records.compact.map {|record| record.send(through_association)}.flatten
        end
      end

      # FIXME: quoting
      def preload_belongs_to_association(records, reflection, preload_options={})
        options = reflection.options
        primary_key_name = reflection.primary_key_name

        if options[:polymorphic]
          polymorph_type = options[:foreign_type]
          klasses_and_ids = {}

          # Construct a mapping from klass to a list of ids to load and a mapping of those ids back to their parent_records
          records.each do |record|
            if klass = record.send(polymorph_type)
              klass_id = record.send(primary_key_name)

              id_map = klasses_and_ids[klass] ||= {}
              id_list_for_klass_id = (id_map[klass_id] ||= [])
              id_list_for_klass_id << record
            end
          end
          klasses_and_ids = klasses_and_ids.to_a
        else
          id_map = {}
          records.each do |record|
            mapped_records = (id_map[record.send(primary_key_name)] ||= [])
            mapped_records << record
          end
          klasses_and_ids = [[reflection.klass.name, id_map]]
        end

        klasses_and_ids.each do |klass_and_id|
          klass_name, id_map = *klass_and_id
          klass = klass_name.constantize

          table_name = klass.table_name
          primary_key = klass.primary_key
          conditions = "#{table_name}.#{primary_key} IN (?)"
          conditions << append_conditions(options, preload_options)
          associated_records = klass.find(:all, :conditions => [conditions, id_map.keys.uniq],
                                          :include => options[:include],
                                          :select => options[:select],
                                          :joins => options[:joins],
                                          :order => options[:order])
          set_association_single_records(id_map, reflection.name, associated_records, primary_key)
        end
      end

      # FIXME: quoting
      def find_associated_records(ids, reflection, preload_options)
        options = reflection.options
        table_name = reflection.klass.table_name

        if interface = reflection.options[:as]
          conditions = "#{reflection.klass.table_name}.#{interface}_id IN (?) and #{reflection.klass.table_name}.#{interface}_type = '#{self.base_class.name.demodulize}'"
        else
          foreign_key = reflection.primary_key_name
          conditions = "#{reflection.klass.table_name}.#{foreign_key} IN (?)"
        end

        conditions << append_conditions(options, preload_options)

        reflection.klass.find(:all,
                              :select => (options[:select] || "#{table_name}.*"),
                              :include => options[:include],
                              :conditions => [conditions, ids],
                              :joins => options[:joins],
                              :group => options[:group],
                              :order => options[:order])
      end


      def interpolate_sql_for_preload(sql)
        instance_eval("%@#{sql.gsub('@', '\@')}@")
      end

      def append_conditions(options, preload_options)
        sql = ""
        sql << " AND (#{interpolate_sql_for_preload(sanitize_sql(options[:conditions]))})" if options[:conditions]
        sql << " AND (#{sanitize_sql preload_options[:conditions]})" if preload_options[:conditions]
        sql
      end

    end
  end
end