aboutsummaryrefslogtreecommitdiffstats
path: root/activerecord/lib/active_record/relation/delegation.rb
blob: 383dc1bf4b127dee907fae53eeea9515b8845159 (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
# frozen_string_literal: true

module ActiveRecord
  module Delegation # :nodoc:
    module DelegateCache # :nodoc:
      def relation_delegate_class(klass)
        @relation_delegate_cache[klass]
      end

      def initialize_relation_delegate_cache
        @relation_delegate_cache = cache = {}
        [
          ActiveRecord::Relation,
          ActiveRecord::Associations::CollectionProxy,
          ActiveRecord::AssociationRelation
        ].each do |klass|
          delegate = Class.new(klass) {
            include ClassSpecificRelation
          }
          include_relation_methods(delegate)
          mangled_name = klass.name.gsub("::", "_")
          const_set mangled_name, delegate
          private_constant mangled_name

          cache[klass] = delegate
        end
      end

      def inherited(child_class)
        child_class.initialize_relation_delegate_cache
        super
      end

      protected
        def include_relation_methods(delegate)
          superclass.include_relation_methods(delegate) unless base_class?
          delegate.include generated_relation_methods
        end

      private
        def generated_relation_methods
          @generated_relation_methods ||= Module.new.tap do |mod|
            mod_name = "GeneratedRelationMethods"
            const_set mod_name, mod
            private_constant mod_name
          end
        end

        def generate_relation_method(method)
          if /\A[a-zA-Z_]\w*[!?]?\z/.match?(method)
            generated_relation_methods.module_eval <<-RUBY, __FILE__, __LINE__ + 1
              def #{method}(*args, &block)
                scoping { klass.#{method}(*args, &block) }
              end
            RUBY
          else
            generated_relation_methods.send(:define_method, method) do |*args, &block|
              scoping { klass.public_send(method, *args, &block) }
            end
          end
        end
    end

    extend ActiveSupport::Concern

    # This module creates compiled delegation methods dynamically at runtime, which makes
    # subsequent calls to that method faster by avoiding method_missing. The delegations
    # may vary depending on the klass of a relation, so we create a subclass of Relation
    # for each different klass, and the delegations are compiled into that subclass only.

    delegate :to_xml, :encode_with, :length, :each, :join,
             :[], :&, :|, :+, :-, :sample, :reverse, :rotate, :compact, :in_groups, :in_groups_of,
             :to_sentence, :to_formatted_s, :as_json,
             :shuffle, :split, :slice, :index, :rindex, to: :records

    delegate :primary_key, :connection, to: :klass

    module ClassSpecificRelation # :nodoc:
      extend ActiveSupport::Concern

      included do
        @delegation_mutex = Mutex.new
      end

      module ClassMethods # :nodoc:
        def name
          superclass.name
        end

        def delegate_to_scoped_klass(method)
          @delegation_mutex.synchronize do
            return if method_defined?(method)

            if /\A[a-zA-Z_]\w*[!?]?\z/.match?(method)
              module_eval <<-RUBY, __FILE__, __LINE__ + 1
                def #{method}(*args, &block)
                  scoping { @klass.#{method}(*args, &block) }
                end
              RUBY
            else
              define_method method do |*args, &block|
                scoping { @klass.public_send(method, *args, &block) }
              end
            end
          end
        end
      end

      private

        def method_missing(method, *args, &block)
          if @klass.respond_to?(method)
            self.class.delegate_to_scoped_klass(method)
            scoping { @klass.public_send(method, *args, &block) }
          elsif @delegate_to_klass && @klass.respond_to?(method, true)
            ActiveSupport::Deprecation.warn \
              "Delegating missing #{method} method to #{@klass}. " \
              "Accessibility of private/protected class methods in :scope is deprecated and will be removed in Rails 6.0."
            @klass.send(method, *args, &block)
          elsif arel.respond_to?(method)
            ActiveSupport::Deprecation.warn \
              "Delegating #{method} to arel is deprecated and will be removed in Rails 6.0."
            arel.public_send(method, *args, &block)
          else
            super
          end
        end
    end

    module ClassMethods # :nodoc:
      def create(klass, *args)
        relation_class_for(klass).new(klass, *args)
      end

      private

        def relation_class_for(klass)
          klass.relation_delegate_class(self)
        end
    end

    private
      def respond_to_missing?(method, _)
        super || @klass.respond_to?(method) || arel.respond_to?(method)
      end
  end
end