aboutsummaryrefslogtreecommitdiffstats
path: root/activerecord/lib/active_record/persistence.rb
blob: 50166c43857eec2a3bf57f38a9af3d667af7a2fc (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
module ActiveRecord
  # = Active Record Persistence
  module Persistence
    # Returns true if this object hasn't been saved yet -- that is, a record 
    # for the object doesn't exist in the data store yet; otherwise, returns false.
    def new_record?
      @new_record
    end

    # Returns true if this object has been destroyed, otherwise returns false.
    def destroyed?
      @destroyed
    end

    # Returns if the record is persisted, i.e. it's not a new record and it was
    # not destroyed.
    def persisted?
      !(new_record? || destroyed?)
    end

    # :call-seq:
    #   save(options)
    #
    # Saves the model.
    #
    # If the model is new a record gets created in the database, otherwise
    # the existing record gets updated.
    #
    # By default, save always run validations. If any of them fail the action
    # is cancelled and +save+ returns +false+. However, if you supply
    # :validate => false, validations are bypassed altogether. See
    # ActiveRecord::Validations for more information.
    #
    # There's a series of callbacks associated with +save+. If any of the
    # <tt>before_*</tt> callbacks return +false+ the action is cancelled and
    # +save+ returns +false+. See ActiveRecord::Callbacks for further
    # details.
    def save(*)
      create_or_update
    end

    # Saves the model.
    #
    # If the model is new a record gets created in the database, otherwise
    # the existing record gets updated.
    #
    # With <tt>save!</tt> validations always run. If any of them fail
    # ActiveRecord::RecordInvalid gets raised. See ActiveRecord::Validations
    # for more information.
    #
    # There's a series of callbacks associated with <tt>save!</tt>. If any of
    # the <tt>before_*</tt> callbacks return +false+ the action is cancelled
    # and <tt>save!</tt> raises ActiveRecord::RecordNotSaved. See
    # ActiveRecord::Callbacks for further details.
    def save!(*)
      create_or_update || raise(RecordNotSaved)
    end

    # Deletes the record in the database and freezes this instance to
    # reflect that no changes should be made (since they can't be
    # persisted). Returns the frozen instance.
    #
    # The row is simply removed with a SQL +DELETE+ statement on the
    # record's primary key, and no callbacks are executed.
    #
    # To enforce the object's +before_destroy+ and +after_destroy+
    # callbacks, Observer methods, or any <tt>:dependent</tt> association
    # options, use <tt>#destroy</tt>.
    def delete
      self.class.delete(id) if persisted?
      @destroyed = true
      freeze
    end

    # Deletes the record in the database and freezes this instance to reflect 
    # that no changes should be made (since they can't be persisted).
    def destroy
      if persisted?
        self.class.unscoped.where(self.class.arel_table[self.class.primary_key].eq(id)).delete_all
      end

      @destroyed = true
      freeze
    end

    # Returns an instance of the specified +klass+ with the attributes of the 
    # current record. This is mostly useful in relation to single-table 
    # inheritance structures where you want a subclass to appear as the 
    # superclass. This can be used along with record identification in 
    # Action Pack to allow, say, <tt>Client < Company</tt> to do something 
    # like render <tt>:partial => @client.becomes(Company)</tt> to render that
    # instance using the companies/company partial instead of clients/client.
    #
    # Note: The new instance will share a link to the same attributes as the original class. So any change to the attributes in either
    # instance will affect the other.
    def becomes(klass)
      became = klass.new
      became.instance_variable_set("@attributes", @attributes)
      became.instance_variable_set("@attributes_cache", @attributes_cache)
      became.instance_variable_set("@new_record", new_record?)
      became.instance_variable_set("@destroyed", destroyed?)
      became
    end

    # Updates a single attribute and saves the record without going through the normal validation procedure.
    # This is especially useful for boolean flags on existing records. The regular +update_attribute+ method
    # in Base is replaced with this when the validations module is mixed in, which it is by default.
    def update_attribute(name, value)
      send("#{name}=", value)
      save(:validate => false)
    end

    # Updates all the attributes from the passed-in Hash and saves the record. 
    # If the object is invalid, the saving will fail and false will be returned.
    def update_attributes(attributes)
      self.attributes = attributes
      save
    end

    # Updates an object just like Base.update_attributes but calls save! instead
    # of save so an exception is raised if the record is invalid.
    def update_attributes!(attributes)
      self.attributes = attributes
      save!
    end

    # Initializes +attribute+ to zero if +nil+ and adds the value passed as +by+ (default is 1).
    # The increment is performed directly on the underlying attribute, no setter is invoked.
    # Only makes sense for number-based attributes. Returns +self+.
    def increment(attribute, by = 1)
      self[attribute] ||= 0
      self[attribute] += by
      self
    end

    # Wrapper around +increment+ that saves the record. This method differs from
    # its non-bang version in that it passes through the attribute setter.
    # Saving is not subjected to validation checks. Returns +true+ if the
    # record could be saved.
    def increment!(attribute, by = 1)
      increment(attribute, by).update_attribute(attribute, self[attribute])
    end

    # Initializes +attribute+ to zero if +nil+ and subtracts the value passed as +by+ (default is 1).
    # The decrement is performed directly on the underlying attribute, no setter is invoked.
    # Only makes sense for number-based attributes. Returns +self+.
    def decrement(attribute, by = 1)
      self[attribute] ||= 0
      self[attribute] -= by
      self
    end

    # Wrapper around +decrement+ that saves the record. This method differs from
    # its non-bang version in that it passes through the attribute setter.
    # Saving is not subjected to validation checks. Returns +true+ if the
    # record could be saved.
    def decrement!(attribute, by = 1)
      decrement(attribute, by).update_attribute(attribute, self[attribute])
    end

    # Assigns to +attribute+ the boolean opposite of <tt>attribute?</tt>. So
    # if the predicate returns +true+ the attribute will become +false+. This
    # method toggles directly the underlying value without calling any setter.
    # Returns +self+.
    def toggle(attribute)
      self[attribute] = !send("#{attribute}?")
      self
    end

    # Wrapper around +toggle+ that saves the record. This method differs from
    # its non-bang version in that it passes through the attribute setter.
    # Saving is not subjected to validation checks. Returns +true+ if the
    # record could be saved.
    def toggle!(attribute)
      toggle(attribute).update_attribute(attribute, self[attribute])
    end

    # Reloads the attributes of this object from the database.
    # The optional options argument is passed to find when reloading so you
    # may do e.g. record.reload(:lock => true) to reload the same record with
    # an exclusive row lock.
    def reload(options = nil)
      clear_aggregation_cache
      clear_association_cache
      @attributes.update(self.class.unscoped { self.class.find(self.id, options) }.instance_variable_get('@attributes'))
      @attributes_cache = {}
      self
    end

  private
    def create_or_update
      raise ReadOnlyRecord if readonly?
      result = new_record? ? create : update
      result != false
    end

    # Updates the associated record with values matching those of the instance attributes.
    # Returns the number of affected rows.
    def update(attribute_names = @attributes.keys)
      attributes_with_values = arel_attributes_values(false, false, attribute_names)
      return 0 if attributes_with_values.empty?
      self.class.unscoped.where(self.class.arel_table[self.class.primary_key].eq(id)).arel.update(attributes_with_values)
    end

    # Creates a record with values matching those of the instance attributes
    # and returns its id.
    def create
      if self.id.nil? && connection.prefetch_primary_key?(self.class.table_name)
        self.id = connection.next_sequence_value(self.class.sequence_name)
      end

      attributes_values = arel_attributes_values

      new_id = if attributes_values.empty?
        self.class.unscoped.insert connection.empty_insert_statement_value
      else
        self.class.unscoped.insert attributes_values
      end

      self.id ||= new_id

      @new_record = false
      id
    end

    # Initializes the attributes array with keys matching the columns from the linked table and
    # the values matching the corresponding default value of that column, so
    # that a new instance, or one populated from a passed-in Hash, still has all the attributes
    # that instances loaded from the database would.
    def attributes_from_column_definition
      self.class.columns.inject({}) do |attributes, column|
        attributes[column.name] = column.default unless column.name == self.class.primary_key
        attributes
      end
    end
  end
end