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ActiveRecord::Persistence

Active Record Persistence

Public Instance Methods

becomes(klass) click to toggle source

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.

     # File lib/active_record/persistence.rb, line 96
 96:     def becomes(klass)
 97:       became = klass.new
 98:       became.instance_variable_set("@attributes", @attributes)
 99:       became.instance_variable_set("@attributes_cache", @attributes_cache)
100:       became.instance_variable_set("@new_record", new_record?)
101:       became.instance_variable_set("@destroyed", destroyed?)
102:       became
103:     end
decrement(attribute, by = 1) click to toggle source

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.

     # File lib/active_record/persistence.rb, line 163
163:     def decrement(attribute, by = 1)
164:       self[attribute] ||= 0
165:       self[attribute] -= by
166:       self
167:     end
decrement!(attribute, by = 1) click to toggle source

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.

     # File lib/active_record/persistence.rb, line 173
173:     def decrement!(attribute, by = 1)
174:       decrement(attribute, by).update_attribute(attribute, self[attribute])
175:     end
delete() click to toggle source

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 #.

    # File lib/active_record/persistence.rb, line 69
69:     def delete
70:       self.class.delete(id) if persisted?
71:       @destroyed = true
72:       freeze
73:     end
destroy() click to toggle source

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

    # File lib/active_record/persistence.rb, line 77
77:     def destroy
78:       if persisted?
79:         self.class.unscoped.where(self.class.arel_table[self.class.primary_key].eq(id)).delete_all
80:       end
81: 
82:       @destroyed = true
83:       freeze
84:     end
destroyed?() click to toggle source

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

    # File lib/active_record/persistence.rb, line 11
11:     def destroyed?
12:       @destroyed
13:     end
increment(attribute, by = 1) click to toggle source

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.

     # File lib/active_record/persistence.rb, line 146
146:     def increment(attribute, by = 1)
147:       self[attribute] ||= 0
148:       self[attribute] += by
149:       self
150:     end
increment!(attribute, by = 1) click to toggle source

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.

     # File lib/active_record/persistence.rb, line 156
156:     def increment!(attribute, by = 1)
157:       increment(attribute, by).update_attribute(attribute, self[attribute])
158:     end
new_record?() click to toggle source

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.

   # File lib/active_record/persistence.rb, line 6
6:     def new_record?
7:       @new_record
8:     end
persisted?() click to toggle source

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

    # File lib/active_record/persistence.rb, line 17
17:     def persisted?
18:       !(new_record? || destroyed?)
19:     end
reload(options = nil) click to toggle source

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.

     # File lib/active_record/persistence.rb, line 198
198:     def reload(options = nil)
199:       clear_aggregation_cache
200:       clear_association_cache
201:       @attributes.update(self.class.unscoped { self.class.find(self.id, options) }.instance_variable_get('@attributes'))
202:       @attributes_cache = {}
203:       self
204:     end
save(options) click to toggle source

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.

    # File lib/active_record/persistence.rb, line 38
38:     def save(*)
39:       create_or_update
40:     end
save!(*) click to toggle source

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.

    # File lib/active_record/persistence.rb, line 55
55:     def save!(*)
56:       create_or_update || raise(RecordNotSaved)
57:     end
toggle(attribute) click to toggle source

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.

     # File lib/active_record/persistence.rb, line 181
181:     def toggle(attribute)
182:       self[attribute] = !send("#{attribute}?")
183:       self
184:     end
toggle!(attribute) click to toggle source

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.

     # File lib/active_record/persistence.rb, line 190
190:     def toggle!(attribute)
191:       toggle(attribute).update_attribute(attribute, self[attribute])
192:     end
touch(name = nil) click to toggle source

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
     # File lib/active_record/persistence.rb, line 226
226:     def touch(name = nil)
227:       attributes = timestamp_attributes_for_update_in_model
228:       unless attributes.blank?
229:         attributes << name if name
230: 
231:         current_time = current_time_from_proper_timezone
232:         changes = {}
233: 
234:         attributes.each do |column|
235:           changes[column.to_s] = write_attribute(column.to_s, current_time)
236:         end
237: 
238:         @changed_attributes.except!(*changes.keys)
239:         primary_key = self.class.primary_key
240:         self.class.update_all(changes, { primary_key => self[primary_key] }) == 1
241:       end
242:     end
update_attribute(name, value) click to toggle source

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.

     # File lib/active_record/persistence.rb, line 113
113:     def update_attribute(name, value)
114:       name = name.to_s
115:       raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name)
116:       send("#{name}=", value)
117:       save(:validate => false)
118:     end
update_attributes(attributes) click to toggle source

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.

     # File lib/active_record/persistence.rb, line 123
123:     def update_attributes(attributes)
124:       # The following transaction covers any possible database side-effects of the
125:       # attributes assignment. For example, setting the IDs of a child collection.
126:       with_transaction_returning_status do
127:         self.attributes = attributes
128:         save
129:       end
130:     end
update_attributes!(attributes) click to toggle source

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

     # File lib/active_record/persistence.rb, line 134
134:     def update_attributes!(attributes)
135:       # The following transaction covers any possible database side-effects of the
136:       # attributes assignment. For example, setting the IDs of a child collection.
137:       with_transaction_returning_status do
138:         self.attributes = attributes
139:         save!
140:       end
141:     end

Private Instance Methods

attributes_from_column_definition() click to toggle source

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.

     # File lib/active_record/persistence.rb, line 284
284:     def attributes_from_column_definition
285:       self.class.columns.inject({}) do |attributes, column|
286:         attributes[column.name] = column.default unless column.name == self.class.primary_key
287:         attributes
288:       end
289:     end
create() click to toggle source

Creates a record with values matching those of the instance attributes and returns its id.

     # File lib/active_record/persistence.rb, line 261
261:     def create
262:       if self.id.nil? && connection.prefetch_primary_key?(self.class.table_name)
263:         self.id = connection.next_sequence_value(self.class.sequence_name)
264:       end
265: 
266:       attributes_values = arel_attributes_values
267: 
268:       new_id = if attributes_values.empty?
269:         self.class.unscoped.insert connection.empty_insert_statement_value
270:       else
271:         self.class.unscoped.insert attributes_values
272:       end
273: 
274:       self.id ||= new_id
275: 
276:       @new_record = false
277:       id
278:     end
create_or_update() click to toggle source
     # File lib/active_record/persistence.rb, line 245
245:     def create_or_update
246:       raise ReadOnlyRecord if readonly?
247:       result = new_record? ? create : update
248:       result != false
249:     end
update(attribute_names = @attributes.keys) click to toggle source

Updates the associated record with values matching those of the instance attributes. Returns the number of affected rows.

     # File lib/active_record/persistence.rb, line 253
253:     def update(attribute_names = @attributes.keys)
254:       attributes_with_values = arel_attributes_values(false, false, attribute_names)
255:       return 0 if attributes_with_values.empty?
256:       self.class.unscoped.where(self.class.arel_table[self.class.primary_key].eq(id)).arel.update(attributes_with_values)
257:     end

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