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 # 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. 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 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. 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 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. 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, 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. 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. # 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. # def update_attribute(name, value) name = name.to_s raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name) send("#{name}=", value) save(:validate => false) end # 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. def update_attributes(attributes) # The following transaction covers any possible database side-effects of the # attributes assignment. For example, setting the IDs of a child collection. with_transaction_returning_status do self.attributes = attributes save end end # Updates its receiver just like +update_attributes+ but calls save! instead # of +save+, so an exception is raised if the record is invalid. def update_attributes!(attributes) # The following transaction covers any possible database side-effects of the # attributes assignment. For example, setting the IDs of a child collection. with_transaction_returning_status do self.attributes = attributes save! end 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 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+. 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 # 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 def touch(name = nil) attributes = timestamp_attributes_for_update_in_model unless attributes.blank? attributes << name if name current_time = current_time_from_proper_timezone changes = {} attributes.each do |column| changes[column.to_s] = write_attribute(column.to_s, current_time) end @changed_attributes.except!(*changes.keys) primary_key = self.class.primary_key self.class.update_all(changes, { primary_key => self[primary_key] }) == 1 end 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