Active Record Persistence

Methods
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Classes and Modules
Instance Public methods
becomes(klass)

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, Client < Company to do something like render :partial => @client.becomes(Company) 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.

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 158
158:     def becomes(klass)
159:       became = klass.new
160:       became.instance_variable_set("@attributes", @attributes)
161:       became.instance_variable_set("@attributes_cache", @attributes_cache)
162:       became.instance_variable_set("@new_record", new_record?)
163:       became.instance_variable_set("@destroyed", destroyed?)
164:       became.instance_variable_set("@errors", errors)
165:       became.type = klass.name unless self.class.descends_from_active_record?
166:       became
167:     end
decrement(attribute, by = 1)

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.

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 248
248:     def decrement(attribute, by = 1)
249:       self[attribute] ||= 0
250:       self[attribute] -= by
251:       self
252:     end
decrement!(attribute, by = 1)

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.

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 258
258:     def decrement!(attribute, by = 1)
259:       decrement(attribute, by).update_attribute(attribute, self[attribute])
260:     end
delete()

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 an 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 :dependent association options, use destroy.

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 117
117:     def delete
118:       if persisted?
119:         self.class.delete(id)
120:         IdentityMap.remove(self) if IdentityMap.enabled?
121:       end
122:       @destroyed = true
123:       freeze
124:     end
destroy()

Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can’t be persisted).

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 128
128:     def destroy
129:       destroy_associations
130: 
131:       if persisted?
132:         IdentityMap.remove(self) if IdentityMap.enabled?
133:         pk         = self.class.primary_key
134:         column     = self.class.columns_hash[pk]
135:         substitute = connection.substitute_at(column, 0)
136: 
137:         relation = self.class.unscoped.where(
138:           self.class.arel_table[pk].eq(substitute))
139: 
140:         relation.bind_values = [[column, id]]
141:         relation.delete_all
142:       end
143: 
144:       @destroyed = true
145:       freeze
146:     end
destroyed?()

Returns true if this object has been destroyed, otherwise returns false.

Source: show | on GitHub 

    # File activerecord/lib/active_record/persistence.rb, line 58
58:     def destroyed?
59:       @destroyed
60:     end
increment(attribute, by = 1)

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.

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 231
231:     def increment(attribute, by = 1)
232:       self[attribute] ||= 0
233:       self[attribute] += by
234:       self
235:     end
increment!(attribute, by = 1)

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.

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 241
241:     def increment!(attribute, by = 1)
242:       increment(attribute, by).update_attribute(attribute, self[attribute])
243:     end
new_record?()

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.

Source: show | on GitHub 

    # File activerecord/lib/active_record/persistence.rb, line 53
53:     def new_record?
54:       @new_record
55:     end
persisted?()

Returns if the record is persisted, i.e. it’s not a new record and it was not destroyed.

Source: show | on GitHub 

    # File activerecord/lib/active_record/persistence.rb, line 64
64:     def persisted?
65:       !(new_record? || destroyed?)
66:     end
reload(options = nil)

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.

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 283
283:     def reload(options = nil)
284:       clear_aggregation_cache
285:       clear_association_cache
286: 
287:       IdentityMap.without do
288:         fresh_object = self.class.unscoped { self.class.find(self.id, options) }
289:         @attributes.update(fresh_object.instance_variable_get('@attributes'))
290:       end
291: 
292:       @attributes_cache = {}
293:       self
294:     end
save(*)

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 before_* callbacks return false the action is cancelled and save returns false. See ActiveRecord::Callbacks for further details.

Source: show | on GitHub 

    # File activerecord/lib/active_record/persistence.rb, line 82
82:     def save(*)
83:       begin
84:         create_or_update
85:       rescue ActiveRecord::RecordInvalid
86:         false
87:       end
88:     end
save!(*)

Saves the model.

If the model is new a record gets created in the database, otherwise the existing record gets updated.

With save! 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 save!. If any of the before_* callbacks return false the action is cancelled and save! raises ActiveRecord::RecordNotSaved. See ActiveRecord::Callbacks for further details.

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 103
103:     def save!(*)
104:       create_or_update || raise(RecordNotSaved)
105:     end
toggle(attribute)

Assigns to attribute the boolean opposite of attribute?. So if the predicate returns true the attribute will become false. This method toggles directly the underlying value without calling any setter. Returns self.

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 266
266:     def toggle(attribute)
267:       self[attribute] = !send("#{attribute}?")
268:       self
269:     end
toggle!(attribute)

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.

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 275
275:     def toggle!(attribute)
276:       toggle(attribute).update_attribute(attribute, self[attribute])
277:     end
touch(name = nil)

Saves the record with the updated_at/on attributes set to the current time. Please note that no validation is performed and no callbacks are executed. If an attribute name is passed, that attribute is updated along with updated_at/on attributes. 

  product.touch               # updates updated_at/on
  product.touch(:designed_at) # updates the designed_at attribute and updated_at/on

If used along with belongs_to then touch will invoke touch method on associated object. 

  class Brake < ActiveRecord::Base
    belongs_to :car, :touch => true
  end

  class Car < ActiveRecord::Base
    belongs_to :corporation, :touch => true
  end

  # triggers @brake.car.touch and @brake.car.corporation.touch
  @brake.touch

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 316
316:     def touch(name = nil)
317:       attributes = timestamp_attributes_for_update_in_model
318:       attributes << name if name
319: 
320:       unless attributes.empty?
321:         current_time = current_time_from_proper_timezone
322:         changes = {}
323: 
324:         attributes.each do |column|
325:           changes[column.to_s] = write_attribute(column.to_s, current_time)
326:         end
327: 
328:         changes[self.class.locking_column] = increment_lock if locking_enabled?
329: 
330:         @changed_attributes.except!(*changes.keys)
331:         primary_key = self.class.primary_key
332:         self.class.unscoped.update_all(changes, { primary_key => self[primary_key] }) == 1
333:       end
334:     end
update_attribute(name, value)

Updates a single attribute and saves the record. This is especially useful for boolean flags on existing records. Also note that

  • Validation is skipped.
  • Callbacks are invoked.
  • updated_at/updated_on column is updated if that column is available.
  • Updates all the attributes that are dirty in this object.

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 177
177:     def update_attribute(name, value)
178:       name = name.to_s
179:       raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name)
180:       send("#{name}=", value)
181:       save(:validate => false)
182:     end
update_attributes(attributes, options = {})

Updates the attributes of the model from the passed-in hash and saves the record, all wrapped in a transaction. If the object is invalid, the saving will fail and false will be returned.

When updating model attributes, mass-assignment security protection is respected. If no :as option is supplied then the :default role will be used. If you want to bypass the protection given by attr_protected and attr_accessible then you can do so using the :without_protection option.

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 208
208:     def update_attributes(attributes, options = {})
209:       # The following transaction covers any possible database side-effects of the
210:       # attributes assignment. For example, setting the IDs of a child collection.
211:       with_transaction_returning_status do
212:         self.assign_attributes(attributes, options)
213:         save
214:       end
215:     end
update_attributes!(attributes, options = {})

Updates its receiver just like update_attributes but calls save! instead of save, so an exception is raised if the record is invalid.

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 219
219:     def update_attributes!(attributes, options = {})
220:       # The following transaction covers any possible database side-effects of the
221:       # attributes assignment. For example, setting the IDs of a child collection.
222:       with_transaction_returning_status do
223:         self.assign_attributes(attributes, options)
224:         save!
225:       end
226:     end
update_column(name, value)

Updates a single attribute of an object, without calling save.

  • Validation is skipped.
  • Callbacks are skipped.
  • updated_at/updated_on column is not updated if that column is available.

Raises an ActiveRecordError when called on new objects, or when the name attribute is marked as readonly.

Source: show | on GitHub 

     # File activerecord/lib/active_record/persistence.rb, line 192
192:     def update_column(name, value)
193:       name = name.to_s
194:       raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name)
195:       raise ActiveRecordError, "can not update on a new record object" unless persisted?
196:       raw_write_attribute(name, value)
197:       self.class.update_all({ name => value }, self.class.primary_key => id) == 1
198:     end