aboutsummaryrefslogtreecommitdiffstats
path: root/activerecord/lib/active_record/enum.rb
blob: d62cd3f92ae98bbfdeb873f77198b82d02edf5b3 (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
# frozen_string_literal: true

require "active_support/core_ext/object/deep_dup"

module ActiveRecord
  # Declare an enum attribute where the values map to integers in the database,
  # but can be queried by name. Example:
  #
  #   class Conversation < ActiveRecord::Base
  #     enum status: [ :active, :archived ]
  #   end
  #
  #   # conversation.update! status: 0
  #   conversation.active!
  #   conversation.active? # => true
  #   conversation.status  # => "active"
  #
  #   # conversation.update! status: 1
  #   conversation.archived!
  #   conversation.archived? # => true
  #   conversation.status    # => "archived"
  #
  #   # conversation.status = 1
  #   conversation.status = "archived"
  #
  #   conversation.status = nil
  #   conversation.status.nil? # => true
  #   conversation.status      # => nil
  #
  # Scopes based on the allowed values of the enum field will be provided
  # as well. With the above example:
  #
  #   Conversation.active
  #   Conversation.archived
  #
  # Of course, you can also query them directly if the scopes don't fit your
  # needs:
  #
  #   Conversation.where(status: [:active, :archived])
  #   Conversation.where.not(status: :active)
  #
  # You can set the default value from the database declaration, like:
  #
  #   create_table :conversations do |t|
  #     t.column :status, :integer, default: 0
  #   end
  #
  # Good practice is to let the first declared status be the default.
  #
  # Finally, it's also possible to explicitly map the relation between attribute and
  # database integer with a hash:
  #
  #   class Conversation < ActiveRecord::Base
  #     enum status: { active: 0, archived: 1 }
  #   end
  #
  # Note that when an array is used, the implicit mapping from the values to database
  # integers is derived from the order the values appear in the array. In the example,
  # <tt>:active</tt> is mapped to +0+ as it's the first element, and <tt>:archived</tt>
  # is mapped to +1+. In general, the +i+-th element is mapped to <tt>i-1</tt> in the
  # database.
  #
  # Therefore, once a value is added to the enum array, its position in the array must
  # be maintained, and new values should only be added to the end of the array. To
  # remove unused values, the explicit hash syntax should be used.
  #
  # In rare circumstances you might need to access the mapping directly.
  # The mappings are exposed through a class method with the pluralized attribute
  # name, which return the mapping in a +HashWithIndifferentAccess+:
  #
  #   Conversation.statuses[:active]    # => 0
  #   Conversation.statuses["archived"] # => 1
  #
  # Use that class method when you need to know the ordinal value of an enum.
  # For example, you can use that when manually building SQL strings:
  #
  #   Conversation.where("status <> ?", Conversation.statuses[:archived])
  #
  # You can use the +:_prefix+ or +:_suffix+ options when you need to define
  # multiple enums with same values. If the passed value is +true+, the methods
  # are prefixed/suffixed with the name of the enum. It is also possible to
  # supply a custom value:
  #
  #   class Conversation < ActiveRecord::Base
  #     enum status: [:active, :archived], _suffix: true
  #     enum comments_status: [:active, :inactive], _prefix: :comments
  #   end
  #
  # With the above example, the bang and predicate methods along with the
  # associated scopes are now prefixed and/or suffixed accordingly:
  #
  #   conversation.active_status!
  #   conversation.archived_status? # => false
  #
  #   conversation.comments_inactive!
  #   conversation.comments_active? # => false

  module Enum
    def self.extended(base) # :nodoc:
      base.class_attribute(:defined_enums, instance_writer: false, default: {})
    end

    def inherited(base) # :nodoc:
      base.defined_enums = defined_enums.deep_dup
      super
    end

    class EnumType < Type::Value # :nodoc:
      delegate :type, to: :subtype

      def initialize(name, mapping, subtype)
        @name = name
        @mapping = mapping
        @subtype = subtype
      end

      def cast(value)
        return if value.blank?

        if mapping.has_key?(value)
          value.to_s
        elsif mapping.has_value?(value)
          mapping.key(value)
        else
          assert_valid_value(value)
        end
      end

      def deserialize(value)
        return if value.nil?
        mapping.key(subtype.deserialize(value))
      end

      def serialize(value)
        mapping.fetch(value, value)
      end

      def assert_valid_value(value)
        unless value.blank? || mapping.has_key?(value) || mapping.has_value?(value)
          raise ArgumentError, "'#{value}' is not a valid #{name}"
        end
      end

      private
        attr_reader :name, :mapping, :subtype
    end

    def enum(definitions)
      klass = self
      enum_prefix = definitions.delete(:_prefix)
      enum_suffix = definitions.delete(:_suffix)
      definitions.each do |name, values|
        assert_valid_enum_definition_values(values)
        # statuses = { }
        enum_values = ActiveSupport::HashWithIndifferentAccess.new
        name = name.to_s

        # def self.statuses() statuses end
        detect_enum_conflict!(name, name.pluralize, true)
        singleton_class.send(:define_method, name.pluralize) { enum_values }
        defined_enums[name] = enum_values

        detect_enum_conflict!(name, name)
        detect_enum_conflict!(name, "#{name}=")

        attr = attribute_alias?(name) ? attribute_alias(name) : name
        decorate_attribute_type(attr, :enum) do |subtype|
          EnumType.new(attr, enum_values, subtype)
        end

        _enum_methods_module.module_eval do
          pairs = values.respond_to?(:each_pair) ? values.each_pair : values.each_with_index
          pairs.each do |label, value|
            if enum_prefix == true
              prefix = "#{name}_"
            elsif enum_prefix
              prefix = "#{enum_prefix}_"
            end
            if enum_suffix == true
              suffix = "_#{name}"
            elsif enum_suffix
              suffix = "_#{enum_suffix}"
            end

            value_method_name = "#{prefix}#{label}#{suffix}"
            enum_values[label] = value
            label = label.to_s

            # def active?() status == "active" end
            klass.send(:detect_enum_conflict!, name, "#{value_method_name}?")
            define_method("#{value_method_name}?") { self[attr] == label }

            # def active!() update!(status: 0) end
            klass.send(:detect_enum_conflict!, name, "#{value_method_name}!")
            define_method("#{value_method_name}!") { update!(attr => value) }

            # scope :active, -> { where(status: 0) }
            klass.send(:detect_enum_conflict!, name, value_method_name, true)
            klass.scope value_method_name, -> { where(attr => value) }
          end
        end
        enum_values.freeze
      end
    end

    private
      def _enum_methods_module
        @_enum_methods_module ||= begin
          mod = Module.new
          include mod
          mod
        end
      end

      def assert_valid_enum_definition_values(values)
        unless values.is_a?(Hash) || values.all? { |v| v.is_a?(Symbol) } || values.all? { |v| v.is_a?(String) }
          error_message = <<~MSG
            Enum values #{values} must be either a hash, an array of symbols, or an array of strings.
          MSG
          raise ArgumentError, error_message
        end

        if values.is_a?(Hash) && values.keys.any?(&:blank?) || values.is_a?(Array) && values.any?(&:blank?)
          raise ArgumentError, "Enum label name must not be blank."
        end
      end

      ENUM_CONFLICT_MESSAGE = \
        "You tried to define an enum named \"%{enum}\" on the model \"%{klass}\", but " \
        "this will generate a %{type} method \"%{method}\", which is already defined " \
        "by %{source}."
      private_constant :ENUM_CONFLICT_MESSAGE

      def detect_enum_conflict!(enum_name, method_name, klass_method = false)
        if klass_method && dangerous_class_method?(method_name)
          raise_conflict_error(enum_name, method_name, type: "class")
        elsif klass_method && method_defined_within?(method_name, Relation)
          raise_conflict_error(enum_name, method_name, type: "class", source: Relation.name)
        elsif !klass_method && dangerous_attribute_method?(method_name)
          raise_conflict_error(enum_name, method_name)
        elsif !klass_method && method_defined_within?(method_name, _enum_methods_module, Module)
          raise_conflict_error(enum_name, method_name, source: "another enum")
        end
      end

      def raise_conflict_error(enum_name, method_name, type: "instance", source: "Active Record")
        raise ArgumentError, ENUM_CONFLICT_MESSAGE % {
          enum: enum_name,
          klass: name,
          type: type,
          method: method_name,
          source: source
        }
      end
  end
end