aboutsummaryrefslogtreecommitdiffstats
path: root/activerecord/lib/active_record/attribute_methods.rb
blob: 2a7a77777d2bb94dd76c6e0a7d8619ac55fb5573 (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
require 'active_support/core_ext/enumerable'
require 'active_support/deprecation'

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

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

      # 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)).
      # (Alias for the protected read_attribute method).
      def [](attr_name)
        read_attribute(attr_name)
      end

      # Updates the attribute identified by <tt>attr_name</tt> with the specified +value+.
      # (Alias for the protected write_attribute method).
      def []=(attr_name, value)
        write_attribute(attr_name, value)
      end
    end

    module ClassMethods
      # Generates all the attribute related methods for columns in the database
      # accessors, mutators and query methods.
      def define_attribute_methods
        unless defined?(@attribute_methods_mutex)
          msg = "It looks like something (probably a gem/plugin) is overriding the " \
                "ActiveRecord::Base.inherited method. It is important that this hook executes so " \
                "that your models are set up correctly. A workaround has been added to stop this " \
                "causing an error in 3.2, but future versions will simply not work if the hook is " \
                "overridden. If you are using Kaminari, please upgrade as it is known to have had " \
                "this problem.\n\n"
          msg << "The following may help track down the problem:"

          meth = method(:inherited)
          if meth.respond_to?(:source_location)
            msg << " #{meth.source_location.inspect}"
          else
            msg << " #{meth.inspect}"
          end
          msg << "\n\n"

          ActiveSupport::Deprecation.warn(msg)

          @attribute_methods_mutex = Mutex.new
        end

        # 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?
        @attribute_methods_generated ||= false
      end

      # We will define the methods as instance methods, but will call them as singleton
      # methods. This allows us to use method_defined? to check if the method exists,
      # which is fast and won't give any false positives from the ancestors (because
      # there are no ancestors).
      def generated_external_attribute_methods
        @generated_external_attribute_methods ||= Module.new { extend self }
      end

      def undefine_attribute_methods
        super
        @attribute_methods_generated = false
      end

      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)
        method_defined_within?(name, Base)
      end

      def method_defined_within?(name, klass, sup = klass.superclass)
        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

      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.
      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)
      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)
      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

    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
    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.
    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.
    def attributes
      Hash[@attributes.map { |name, _| [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)
    #   # => '"2009-01-12 04:48:57"'
    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 empty? (the latter only applies to objects that respond to empty?, most notably Strings).
    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.
    def column_for_attribute(name)
      self.class.columns_hash[name.to_s]
    end

    protected

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

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

    # Returns a copy of the attributes hash where all the values have been safely quoted for use in
    # an Arel insert/update method.
    def arel_attributes_values(include_primary_key = true, include_readonly_attributes = true, attribute_names = @attributes.keys)
      attrs      = {}
      klass      = self.class
      arel_table = klass.arel_table

      attribute_names.each do |name|
        if (column = column_for_attribute(name)) && (include_primary_key || !column.primary)

          if include_readonly_attributes || !self.class.readonly_attributes.include?(name)

            value = if klass.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 type
                      # casted, this code could be simplified
                      read_attribute(name)
                    end

            attrs[arel_table[name]] = value
          end
        end
      end

      attrs
    end

    def attribute_method?(attr_name)
      attr_name == 'id' || (defined?(@attributes) && @attributes.include?(attr_name))
    end
  end
end