aboutsummaryrefslogtreecommitdiffstats
path: root/activerecord/lib/active_record/attribute_methods.rb
blob: 437fd009486bd90dc0d82c1310c8143ae1d1aa84 (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
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
require 'active_support/core_ext/enumerable'

module ActiveRecord
  # = Active Record Attribute Methods
  module AttributeMethods
    extend ActiveSupport::Concern
    include ActiveModel::AttributeMethods

    included do
      include Read
      include Write
      include BeforeTypeCast
      include Query
      include PrimaryKey
      include TimeZoneConversion
      include Dirty
      include Serialization
    end

    module ClassMethods
      # Generates all the attribute related methods for columns in the database
      # accessors, mutators and query methods.
      def define_attribute_methods # :nodoc:
        # Use a mutex; we don't want two thread simaltaneously trying to define
        # attribute methods.
        @attribute_methods_mutex.synchronize do
          return if attribute_methods_generated?
          superclass.define_attribute_methods unless self == base_class
          super(column_names)
          @attribute_methods_generated = true
        end
      end

      def attribute_methods_generated? # :nodoc:
        @attribute_methods_generated ||= false
      end

      def undefine_attribute_methods # :nodoc:
        super if attribute_methods_generated?
        @attribute_methods_generated = false
      end

      # Raises a <tt>ActiveRecord::DangerousAttributeError</tt> exception when an
      # \Active \Record method is defined in the model, otherwise +false+.
      #
      #   class Person < ActiveRecord::Base
      #     def save
      #       'already defined by Active Record'
      #     end
      #   end
      #
      #   Person.instance_method_already_implemented?(:save)
      #   # => ActiveRecord::DangerousAttributeError: save is defined by ActiveRecord
      #
      #   Person.instance_method_already_implemented?(:name)
      #   # => false
      def instance_method_already_implemented?(method_name)
        if dangerous_attribute_method?(method_name)
          raise DangerousAttributeError, "#{method_name} is defined by ActiveRecord"
        end

        if superclass == Base
          super
        else
          # If B < A and A defines its own attribute method, then we don't want to overwrite that.
          defined = method_defined_within?(method_name, superclass, superclass.generated_attribute_methods)
          defined && !ActiveRecord::Base.method_defined?(method_name) || super
        end
      end

      # A method name is 'dangerous' if it is already defined by Active Record, but
      # not by any ancestors. (So 'puts' is not dangerous but 'save' is.)
      def dangerous_attribute_method?(name) # :nodoc:
        method_defined_within?(name, Base)
      end

      def method_defined_within?(name, klass, sup = klass.superclass) # :nodoc:
        if klass.method_defined?(name) || klass.private_method_defined?(name)
          if sup.method_defined?(name) || sup.private_method_defined?(name)
            klass.instance_method(name).owner != sup.instance_method(name).owner
          else
            true
          end
        else
          false
        end
      end

      # Returns +true+ if +attribute+ is an attribute method and table exists,
      # +false+ otherwise.
      #
      #   class Person < ActiveRecord::Base
      #   end
      #
      #   Person.attribute_method?('name')   # => true
      #   Person.attribute_method?(:age=)    # => true
      #   Person.attribute_method?(:nothing) # => false
      def attribute_method?(attribute)
        super || (table_exists? && column_names.include?(attribute.to_s.sub(/=$/, '')))
      end

      # Returns an array of column names as strings if it's not an abstract class and
      # table exists. Otherwise it returns an empty array.
      #
      #   class Person < ActiveRecord::Base
      #   end
      #
      #   Person.attribute_names
      #   # => ["id", "created_at", "updated_at", "name", "age"]
      def attribute_names
        @attribute_names ||= if !abstract_class? && table_exists?
            column_names
          else
            []
          end
      end
    end

    # If we haven't generated any methods yet, generate them, then
    # see if we've created the method we're looking for.
    def method_missing(method, *args, &block) # :nodoc:
      unless self.class.attribute_methods_generated?
        self.class.define_attribute_methods

        if respond_to_without_attributes?(method)
          send(method, *args, &block)
        else
          super
        end
      else
        super
      end
    end

    def attribute_missing(match, *args, &block) # :nodoc:
      if self.class.columns_hash[match.attr_name]
        ActiveSupport::Deprecation.warn(
          "The method `#{match.method_name}', matching the attribute `#{match.attr_name}' has " \
          "dispatched through method_missing. This shouldn't happen, because `#{match.attr_name}' " \
          "is a column of the table. If this error has happened through normal usage of Active " \
          "Record (rather than through your own code or external libraries), please report it as " \
          "a bug."
        )
      end

      super
    end

    # A Person object with a name attribute can ask <tt>person.respond_to?(:name)</tt>,
    # <tt>person.respond_to?(:name=)</tt>, and <tt>person.respond_to?(:name?)</tt>
    # which will all return +true+. It also define the attribute methods if they have
    # not been generated.
    #
    #   class Person < ActiveRecord::Base
    #   end
    #
    #   person = Person.new
    #   person.respond_to(:name)    # => true
    #   person.respond_to(:name=)   # => true
    #   person.respond_to(:name?)   # => true
    #   person.respond_to('age')    # => true
    #   person.respond_to('age=')   # => true
    #   person.respond_to('age?')   # => true
    #   person.respond_to(:nothing) # => false
    def respond_to?(name, include_private = false)
      self.class.define_attribute_methods unless self.class.attribute_methods_generated?
      super
    end

    # Returns +true+ if the given attribute is in the attributes hash, otherwise +false+.
    #
    #   class Person < ActiveRecord::Base
    #   end
    #
    #   person = Person.new
    #   person.has_attribute?(:name)    # => true
    #   person.has_attribute?('age')    # => true
    #   person.has_attribute?(:nothing) # => false
    def has_attribute?(attr_name)
      @attributes.has_key?(attr_name.to_s)
    end

    # Returns an array of names for the attributes available on this object.
    #
    #   class Person < ActiveRecord::Base
    #   end
    #
    #   person = Person.new
    #   person.attribute_names
    #   # => ["id", "created_at", "updated_at", "name", "age"]
    def attribute_names
      @attributes.keys
    end

    # Returns a hash of all the attributes with their names as keys and the values of the attributes as values.
    #
    #   class Person < ActiveRecord::Base
    #   end
    #
    #   person = Person.create(name: 'Francesco', age: 22)
    #   person.attributes
    #   # => {"id"=>3, "created_at"=>Sun, 21 Oct 2012 04:53:04, "updated_at"=>Sun, 21 Oct 2012 04:53:04, "name"=>"Francesco", "age"=>22}
    def attributes
      attribute_names.each_with_object({}) { |name, attrs|
        attrs[name] = read_attribute(name)
      }
    end

    # Returns an <tt>#inspect</tt>-like string for the value of the
    # attribute +attr_name+. String attributes are truncated upto 50
    # characters, and Date and Time attributes are returned in the
    # <tt>:db</tt> format. Other attributes return the value of
    # <tt>#inspect</tt> without modification.
    #
    #   person = Person.create!(name: 'David Heinemeier Hansson ' * 3)
    #
    #   person.attribute_for_inspect(:name)
    #   # => "\"David Heinemeier Hansson David Heinemeier Hansson D...\""
    #
    #   person.attribute_for_inspect(:created_at)
    #   # => "\"2012-10-22 00:15:07\""
    def attribute_for_inspect(attr_name)
      value = read_attribute(attr_name)

      if value.is_a?(String) && value.length > 50
        "#{value[0..50]}...".inspect
      elsif value.is_a?(Date) || value.is_a?(Time)
        %("#{value.to_s(:db)}")
      else
        value.inspect
      end
    end

    # Returns +true+ if the specified +attribute+ has been set by the user or by a
    # database load and is neither +nil+ nor <tt>empty?</tt> (the latter only applies
    # to objects that respond to <tt>empty?</tt>, most notably Strings). Otherwise, +false+.
    # Note that it always returns +true+ with boolean attributes.
    #
    #   class Task < ActiveRecord::Base
    #   end
    #
    #   person = Task.new(title: '', is_done: false)
    #   person.attribute_present?(:title)   # => false
    #   person.attribute_present?(:is_done) # => true
    #   person.name = 'Francesco'
    #   person.is_done = true
    #   person.attribute_present?(:title)   # => true
    #   person.attribute_present?(:is_done) # => true
    def attribute_present?(attribute)
      value = read_attribute(attribute)
      !value.nil? && !(value.respond_to?(:empty?) && value.empty?)
    end

    # Returns the column object for the named attribute. Returns +nil+ if the
    # named attribute not exists.
    #
    #   class Person < ActiveRecord::Base
    #   end
    #
    #   person = Person.new
    #   person.column_for_attribute(:name) # the result depends on the ConnectionAdapter
    #   # => #<ActiveRecord::ConnectionAdapters::SQLite3Column:0x007ff4ab083980 @name="name", @sql_type="varchar(255)", @null=true, ...>
    #
    #   person.column_for_attribute(:nothing)
    #   # => nil
    def column_for_attribute(name)
      # FIXME: should this return a null object for columns that don't exist?
      self.class.columns_hash[name.to_s]
    end

    # Returns the value of the attribute identified by <tt>attr_name</tt> after it has been typecast (for example,
    # "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)). It raises
    # <tt>ActiveModel::MissingAttributeError</tt> if the identified attribute is missing.
    #
    # Alias for the <tt>read_attribute</tt> method.
    #
    #   class Person < ActiveRecord::Base
    #     belongs_to :organization
    #   end
    #
    #   person = Person.new(name: 'Francesco', age: '22')
    #   person[:name] # => "Francesco"
    #   person[:age]  # => 22
    #
    #   person = Person.select('id').first
    #   person[:name]            # => ActiveModel::MissingAttributeError: missing attribute: name
    #   person[:organization_id] # => ActiveModel::MissingAttributeError: missing attribute: organization_id
    def [](attr_name)
      read_attribute(attr_name) { |n| missing_attribute(n, caller) }
    end

    # Updates the attribute identified by <tt>attr_name</tt> with the specified +value+.
    # (Alias for the protected <tt>write_attribute</tt> method).
    #
    #   class Person < ActiveRecord::Base
    #   end
    #
    #   person = Person.new
    #   person[:age] = '22'
    #   person[:age] # => 22
    #   person[:age] # => Fixnum
    def []=(attr_name, value)
      write_attribute(attr_name, value)
    end

    protected

    def clone_attributes(reader_method = :read_attribute, attributes = {}) # :nodoc:
      attribute_names.each do |name|
        attributes[name] = clone_attribute_value(reader_method, name)
      end
      attributes
    end

    def clone_attribute_value(reader_method, attribute_name) # :nodoc:
      value = send(reader_method, attribute_name)
      value.duplicable? ? value.clone : value
    rescue TypeError, NoMethodError
      value
    end

    def arel_attributes_with_values_for_create(attribute_names) # :nodoc:
      arel_attributes_with_values(attributes_for_create(attribute_names))
    end

    def arel_attributes_with_values_for_update(attribute_names) # :nodoc:
      arel_attributes_with_values(attributes_for_update(attribute_names))
    end

    def attribute_method?(attr_name) # :nodoc:
      defined?(@attributes) && @attributes.include?(attr_name)
    end

    private

    # Returns a Hash of the Arel::Attributes and attribute values that have been
    # type casted for use in an Arel insert/update method.
    def arel_attributes_with_values(attribute_names)
      attrs = {}
      arel_table = self.class.arel_table

      attribute_names.each do |name|
        attrs[arel_table[name]] = typecasted_attribute_value(name)
      end
      attrs
    end

    # Filters the primary keys and readonly attributes from the attribute names.
    def attributes_for_update(attribute_names)
      attribute_names.select do |name|
        column_for_attribute(name) && !pk_attribute?(name) && !readonly_attribute?(name)
      end
    end

    # Filters out the primary keys, from the attribute names, when the primary
    # key is to be generated (e.g. the id attribute has no value).
    def attributes_for_create(attribute_names)
      attribute_names.select do |name|
        column_for_attribute(name) && !(pk_attribute?(name) && id.nil?)
      end
    end

    def readonly_attribute?(name)
      self.class.readonly_attributes.include?(name)
    end

    def pk_attribute?(name)
      column_for_attribute(name).primary
    end

    def typecasted_attribute_value(name)
      if self.class.serialized_attributes.include?(name)
        @attributes[name].serialized_value
      else
        # FIXME: we need @attributes to be used consistently.
        # If the values stored in @attributes were already typecasted, this code
        # could be simplified
        read_attribute(name)
      end
    end
  end
end