module ActiveRecord # = Active Record Persistence module Persistence extend ActiveSupport::Concern module ClassMethods # Creates an object (or multiple objects) and saves it to the database, if validations pass. # The resulting object is returned whether the object was saved successfully to the database or not. # # The +attributes+ parameter can be either a Hash or an Array of Hashes. These Hashes describe the # attributes on the objects that are to be created. # # +create+ respects mass-assignment security and accepts either +:as+ or +:without_protection+ options # in the +options+ parameter. # # ==== Examples # # Create a single new object # User.create(first_name: 'Jamie') # # # Create an Array of new objects # User.create([{ first_name: 'Jamie' }, { first_name: 'Jeremy' }]) # # # Create a single object and pass it into a block to set other attributes. # User.create(first_name: 'Jamie') do |u| # u.is_admin = false # end # # # Creating an Array of new objects using a block, where the block is executed for each object: # User.create([{ first_name: 'Jamie' }, { first_name: 'Jeremy' }]) do |u| # u.is_admin = false # end def create(attributes = nil, &block) if attributes.is_a?(Array) attributes.collect { |attr| create(attr, &block) } else object = new(attributes, &block) object.save object end end # Given an attributes hash, +instantiate+ returns a new instance of # the appropriate class. # # For example, +Post.all+ may return Comments, Messages, and Emails # by storing the record's subclass in a +type+ attribute. By calling # +instantiate+ instead of +new+, finder methods ensure they get new # instances of the appropriate class for each record. # # See +ActiveRecord::Inheritance#discriminate_class_for_record+ to see # how this "single-table" inheritance mapping is implemented. def instantiate(record, column_types = {}) klass = discriminate_class_for_record(record) column_types = klass.decorate_columns(column_types.dup) klass.allocate.init_with('attributes' => record, 'column_types' => column_types) end private # Called by +instantiate+ to decide which class to use for a new # record instance. # # See +ActiveRecord::Inheritance#discriminate_class_for_record+ for # the single-table inheritance discriminator. def discriminate_class_for_record(record) self end end # 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? sync_with_transaction_state @new_record end # Returns true if this object has been destroyed, otherwise returns false. def destroyed? sync_with_transaction_state @destroyed end # Returns true if the record is persisted, i.e. it's not a new record and it was # not destroyed, otherwise returns false. 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. # # Attributes marked as readonly are silently ignored if the record is # being updated. def save(*) create_or_update rescue ActiveRecord::RecordInvalid false 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. # # Attributes marked as readonly are silently ignored if the record is # being updated. 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 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). # # There's a series of callbacks associated with destroy. If # the before_destroy callback return +false+ the action is cancelled # and destroy returns +false+. See # ActiveRecord::Callbacks for further details. def destroy raise ReadOnlyRecord if readonly? destroy_associations destroy_row 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). # # There's a series of callbacks associated with destroy!. If # the before_destroy callback return +false+ the action is cancelled # and destroy! raises ActiveRecord::RecordNotDestroyed. See # ActiveRecord::Callbacks for further details. def destroy! destroy || raise(ActiveRecord::RecordNotDestroyed) 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.instance_variable_set("@errors", errors) became end # Wrapper around +becomes+ that also changes the instance's sti column value. # This is especially useful if you want to persist the changed class in your # database. # # Note: The old instance's sti column value will be changed too, as both objects # share the same set of attributes. def becomes!(klass) became = becomes(klass) became.public_send("#{klass.inheritance_column}=", klass.sti_name) unless self.class.descends_from_active_record? 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. # # This method raises an +ActiveRecord::ActiveRecordError+ if the # attribute is marked as readonly. def update_attribute(name, value) name = name.to_s verify_readonly_attribute(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) # 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 assign_attributes(attributes) save end end alias update_attributes update # Updates its receiver just like +update+ but calls save! instead # of +save+, so an exception is raised if the record is invalid. def update!(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 assign_attributes(attributes) save! end end alias update_attributes! update! # Equivalent to update_columns(name => value). def update_column(name, value) update_columns(name => value) end # Updates the attributes directly in the database issuing an UPDATE SQL # statement and sets them in the receiver: # # user.update_columns(last_request_at: Time.current) # # This is the fastest way to update attributes because it goes straight to # the database, but take into account that in consequence the regular update # procedures are totally bypassed. In particular: # # * Validations are skipped. # * Callbacks are skipped. # * +updated_at+/+updated_on+ are not updated. # # This method raises an +ActiveRecord::ActiveRecordError+ when called on new # objects, or when at least one of the attributes is marked as readonly. def update_columns(attributes) raise ActiveRecordError, "can not update on a new record object" unless persisted? attributes.each_key do |key| verify_readonly_attribute(key.to_s) end updated_count = self.class.unscoped.where(self.class.primary_key => id).update_all(attributes) attributes.each do |k, v| raw_write_attribute(k, v) end updated_count == 1 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 record from the database. # # This method modifies the receiver in-place. Attributes are updated, and # caches busted, in particular the associations cache. # # If the record no longer exists in the database ActiveRecord::RecordNotFound # is raised. Otherwise, in addition to the in-place modification the method # returns +self+ for convenience. # # The optional :lock flag option allows you to lock the reloaded record: # # reload(lock: true) # reload with pessimistic locking # # Reloading is commonly used in test suites to test something is actually # written to the database, or when some action modifies the corresponding # row in the database but not the object in memory: # # assert account.deposit!(25) # assert_equal 25, account.credit # check it is updated in memory # assert_equal 25, account.reload.credit # check it is also persisted # # Another commom use case is optimistic locking handling: # # def with_optimistic_retry # begin # yield # rescue ActiveRecord::StaleObjectError # begin # # Reload lock_version in particular. # reload # rescue ActiveRecord::RecordNotFound # # If the record is gone there is nothing to do. # else # retry # end # end # end # def reload(options = nil) clear_aggregation_cache clear_association_cache fresh_object = if options && options[:lock] self.class.unscoped { self.class.lock.find(id) } else self.class.unscoped { self.class.find(id) } end @attributes.update(fresh_object.instance_variable_get('@attributes')) @columns_hash = fresh_object.instance_variable_get('@columns_hash') @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 # # Note that +touch+ must be used on a persisted object, or else an # ActiveRecordError will be thrown. For example: # # ball = Ball.new # ball.touch(:updated_at) # => raises ActiveRecordError # def touch(name = nil) raise ActiveRecordError, "can not touch on a new record object" unless persisted? attributes = timestamp_attributes_for_update_in_model attributes << name if name unless attributes.empty? current_time = current_time_from_proper_timezone changes = {} attributes.each do |column| column = column.to_s changes[column] = write_attribute(column, current_time) end changes[self.class.locking_column] = increment_lock if locking_enabled? @changed_attributes.except!(*changes.keys) primary_key = self.class.primary_key self.class.unscoped.where(primary_key => self[primary_key]).update_all(changes) == 1 end end private # A hook to be overridden by association modules. def destroy_associations end def destroy_row relation_for_destroy.delete_all end def relation_for_destroy pk = self.class.primary_key column = self.class.columns_hash[pk] substitute = self.class.connection.substitute_at(column, 0) relation = self.class.unscoped.where( self.class.arel_table[pk].eq(substitute)) relation.bind_values = [[column, id]] relation end def create_or_update raise ReadOnlyRecord if readonly? result = new_record? ? create_record : update_record result != false end # Updates the associated record with values matching those of the instance attributes. # Returns the number of affected rows. def update_record(attribute_names = @attributes.keys) attributes_values = arel_attributes_with_values_for_update(attribute_names) if attributes_values.empty? 0 else self.class.unscoped.update_record attributes_values, id, id_was end end # Creates a record with values matching those of the instance attributes # and returns its id. def create_record(attribute_names = @attributes.keys) attributes_values = arel_attributes_with_values_for_create(attribute_names) new_id = self.class.unscoped.insert attributes_values self.id ||= new_id if self.class.primary_key @new_record = false id end def verify_readonly_attribute(name) raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name) end end end