ActiveRecord::AutosaveAssociation
这个模块主要是负责自动保存associated records当，它的parent保存的时候。除此之外，也负责删除被标记为destruction的associated records。
所有的保存和删除会在一个事务里进行，如果验证失败error message会在parent上。
# frozen_string_literal: true
module ActiveRecord
# = Active Record Autosave Association
#
# AutosaveAssociation is a module that takes care of automatically saving
# associated records when their parent is saved. In addition to saving, it
# also destroys any associated records that were marked for destruction.
# (See #mark_for_destruction and #marked_for_destruction?).
#
# Saving of the parent, its associations, and the destruction of marked
# associations, all happen inside a transaction. This should never leave the
# database in an inconsistent state.
#
# If validations for any of the associations fail, their error messages will
# be applied to the parent.
#
# Note that it also means that associations marked for destruction won't
# be destroyed directly. They will however still be marked for destruction.
#
# Note that autosave: false is not same as not declaring :autosave.
# When the :autosave option is not present then new association records are
# saved but the updated association records are not saved.
#
# == Validation
#
# Child records are validated unless :validate is +false+.
#
# == Callbacks
#
# Association with autosave option defines several callbacks on your
# model (before_save, after_create, after_update). Please note that
# callbacks are executed in the order they were defined in
# model. You should avoid modifying the association content, before
# autosave callbacks are executed. Placing your callbacks after
# associations is usually a good practice.
#
# === One-to-one Example
#
# class Post < ActiveRecord::Base
# has_one :author, autosave: true
# end
#
# Saving changes to the parent and its associated model can now be performed
# automatically _and_ atomically:
#
# post = Post.find(1)
# post.title # => "The current global position of migrating ducks"
# post.author.name # => "alloy"
#
# post.title = "On the migration of ducks"
# post.author.name = "Eloy Duran"
#
# post.save
# post.reload
# post.title # => "On the migration of ducks"
# post.author.name # => "Eloy Duran"
#
# Destroying an associated model, as part of the parent's save action, is as
# simple as marking it for destruction:
#
# post.author.mark_for_destruction
# post.author.marked_for_destruction? # => true
#
# Note that the model is _not_ yet removed from the database:
#
# id = post.author.id
# Author.find_by(id: id).nil? # => false
#
# post.save
# post.reload.author # => nil
#
# Now it _is_ removed from the database:
#
# Author.find_by(id: id).nil? # => true
#
# === One-to-many Example
#
# When :autosave is not declared new children are saved when their parent is saved:
#
# class Post < ActiveRecord::Base
# has_many :comments # :autosave option is not declared
# end
#
# post = Post.new(title: 'ruby rocks')
# post.comments.build(body: 'hello world')
# post.save # => saves both post and comment
#
# post = Post.create(title: 'ruby rocks')
# post.comments.build(body: 'hello world')
# post.save # => saves both post and comment
#
# post = Post.create(title: 'ruby rocks')
# post.comments.create(body: 'hello world')
# post.save # => saves both post and comment
#
# When :autosave is true all children are saved, no matter whether they
# are new records or not:
#
# class Post < ActiveRecord::Base
# has_many :comments, autosave: true
# end
#
# post = Post.create(title: 'ruby rocks')
# post.comments.create(body: 'hello world')
# post.comments[0].body = 'hi everyone'
# post.comments.build(body: "good morning.")
# post.title += "!"
# post.save # => saves both post and comments.
#
# Destroying one of the associated models as part of the parent's save action
# is as simple as marking it for destruction:
#
# post.comments # => [#, #
# post.comments[1].mark_for_destruction
# post.comments[1].marked_for_destruction? # => true
# post.comments.length # => 2
#
# Note that the model is _not_ yet removed from the database:
#
# id = post.comments.last.id
# Comment.find_by(id: id).nil? # => false
#
# post.save
# post.reload.comments.length # => 1
#
# Now it _is_ removed from the database:
#
# Comment.find_by(id: id).nil? # => true
module AutosaveAssociation
extend ActiveSupport::Concern
module AssociationBuilderExtension #:nodoc:
def self.build(model, reflection)
model.send(:add_autosave_association_callbacks, reflection)
end
def self.valid_options
[ :autosave ]
end
end
included do
Associations::Builder::Association.extensions << AssociationBuilderExtension
mattr_accessor :index_nested_attribute_errors, instance_writer: false, default: false
end
module ClassMethods # :nodoc:
private
def define_non_cyclic_method(name, &block)
return if instance_methods(false).include?(name)
define_method(name) do |*args|
result = true; @_already_called ||= {}
# Loop prevention for validation of associations
unless @_already_called[name]
begin
@_already_called[name] = true
result = instance_eval(&block)
ensure
@_already_called[name] = false
end
end
result
end
end
# Adds validation and save callbacks for the association as specified by
# the +reflection+.
#
# For performance reasons, we don't check whether to validate at runtime.
# However the validation and callback methods are lazy and those methods
# get created when they are invoked for the very first time. However,
# this can change, for instance, when using nested attributes, which is
# called _after_ the association has been defined. Since we don't want
# the callbacks to get defined multiple times, there are guards that
# check if the save or validation methods have already been defined
# before actually defining them.
def add_autosave_association_callbacks(reflection)
save_method = :"autosave_associated_records_for_#{reflection.name}"
if reflection.collection?
before_save :before_save_collection_association
after_save :after_save_collection_association
define_non_cyclic_method(save_method) { save_collection_association(reflection) }
# Doesn't use after_save as that would save associations added in after_create/after_update twice
after_create save_method
after_update save_method
elsif reflection.has_one?
define_method(save_method) { save_has_one_association(reflection) } unless method_defined?(save_method)
# Configures two callbacks instead of a single after_save so that
# the model may rely on their execution order relative to its
# own callbacks.
#
# For example, given that after_creates run before after_saves, if
# we configured instead an after_save there would be no way to fire
# a custom after_create callback after the child association gets
# created.
after_create save_method
after_update save_method
else
define_non_cyclic_method(save_method) { throw(:abort) if save_belongs_to_association(reflection) == false }
before_save save_method
end
define_autosave_validation_callbacks(reflection)
end
def define_autosave_validation_callbacks(reflection)
validation_method = :"validate_associated_records_for_#{reflection.name}"
if reflection.validate? && !method_defined?(validation_method)
if reflection.collection?
method = :validate_collection_association
else
method = :validate_single_association
end
define_non_cyclic_method(validation_method) { send(method, reflection) }
validate validation_method
after_validation :_ensure_no_duplicate_errors
end
end
end
# Reloads the attributes of the object as usual and clears marked_for_destruction flag.
def reload(options = nil)
@marked_for_destruction = false
@destroyed_by_association = nil
super
end
# Marks this record to be destroyed as part of the parent's save transaction.
# This does _not_ actually destroy the record instantly, rather child record will be destroyed
# when parent.save is called.
#
# Only useful if the :autosave option on the parent is enabled for this associated model.
def mark_for_destruction
@marked_for_destruction = true
end
# Returns whether or not this record will be destroyed as part of the parent's save transaction.
#
# Only useful if the :autosave option on the parent is enabled for this associated model.
def marked_for_destruction?
@marked_for_destruction
end
# Records the association that is being destroyed and destroying this
# record in the process.
def destroyed_by_association=(reflection)
@destroyed_by_association = reflection
end
# Returns the association for the parent being destroyed.
#
# Used to avoid updating the counter cache unnecessarily.
def destroyed_by_association
@destroyed_by_association
end
# Returns whether or not this record has been changed in any way (including whether
# any of its nested autosave associations are likewise changed)
def changed_for_autosave?
new_record? || has_changes_to_save? || marked_for_destruction? || nested_records_changed_for_autosave?
end
private
# Returns the record for an association collection that should be validated
# or saved. If +autosave+ is +false+ only new records will be returned,
# unless the parent is/was a new record itself.
def associated_records_to_validate_or_save(association, new_record, autosave)
if new_record || custom_validation_context?
association && association.target
elsif autosave
association.target.find_all(&:changed_for_autosave?)
else
association.target.find_all(&:new_record?)
end
end
# go through nested autosave associations that are loaded in memory (without loading
# any new ones), and return true if is changed for autosave
def nested_records_changed_for_autosave?
@_nested_records_changed_for_autosave_already_called ||= false
return false if @_nested_records_changed_for_autosave_already_called
begin
@_nested_records_changed_for_autosave_already_called = true
self.class._reflections.values.any? do |reflection|
if reflection.options[:autosave]
association = association_instance_get(reflection.name)
association && Array.wrap(association.target).any?(&:changed_for_autosave?)
end
end
ensure
@_nested_records_changed_for_autosave_already_called = false
end
end
# Validate the association if :validate or :autosave is
# turned on for the association.
def validate_single_association(reflection)
association = association_instance_get(reflection.name)
record = association && association.reader
association_valid?(reflection, record) if record && (record.changed_for_autosave? || custom_validation_context?)
end
# Validate the associated records if :validate or
# :autosave is turned on for the association specified by
# +reflection+.
def validate_collection_association(reflection)
if association = association_instance_get(reflection.name)
if records = associated_records_to_validate_or_save(association, new_record?, reflection.options[:autosave])
records.each_with_index { |record, index| association_valid?(reflection, record, index) }
end
end
end
# Returns whether or not the association is valid and applies any errors to
# the parent, self, if it wasn't. Skips any :autosave
# enabled records if they're marked_for_destruction? or destroyed.
def association_valid?(reflection, record, index = nil)
return true if record.destroyed? || (reflection.options[:autosave] && record.marked_for_destruction?)
context = validation_context if custom_validation_context?
unless valid = record.valid?(context)
if reflection.options[:autosave]
indexed_attribute = !index.nil? && (reflection.options[:index_errors] || ActiveRecord::Base.index_nested_attribute_errors)
record.errors.each do |attribute, message|
attribute = normalize_reflection_attribute(indexed_attribute, reflection, index, attribute)
errors[attribute] << message
errors[attribute].uniq!
end
record.errors.details.each_key do |attribute|
reflection_attribute =
normalize_reflection_attribute(indexed_attribute, reflection, index, attribute).to_sym
record.errors.details[attribute].each do |error|
errors.details[reflection_attribute] << error
errors.details[reflection_attribute].uniq!
end
end
else
errors.add(reflection.name)
end
end
valid
end
def normalize_reflection_attribute(indexed_attribute, reflection, index, attribute)
if indexed_attribute
"#{reflection.name}[#{index}].#{attribute}"
else
"#{reflection.name}.#{attribute}"
end
end
# Is used as a before_save callback to check while saving a collection
# association whether or not the parent was a new record before saving.
def before_save_collection_association
@new_record_before_save = new_record?
end
def after_save_collection_association
@new_record_before_save = false
end
# Saves any new associated records, or all loaded autosave associations if
# :autosave is enabled on the association.
#
# In addition, it destroys all children that were marked for destruction
# with #mark_for_destruction.
#
# This all happens inside a transaction, _if_ the Transactions module is included into
# ActiveRecord::Base after the AutosaveAssociation module, which it does by default.
def save_collection_association(reflection)
if association = association_instance_get(reflection.name)
autosave = reflection.options[:autosave]
# By saving the instance variable in a local variable,
# we make the whole callback re-entrant.
new_record_before_save = @new_record_before_save
# reconstruct the scope now that we know the owner's id
association.reset_scope
if records = associated_records_to_validate_or_save(association, new_record_before_save, autosave)
if autosave
records_to_destroy = records.select(&:marked_for_destruction?)
records_to_destroy.each { |record| association.destroy(record) }
records -= records_to_destroy
end
records.each do |record|
next if record.destroyed?
saved = true
if autosave != false && (new_record_before_save || record.new_record?)
if autosave
saved = association.insert_record(record, false)
elsif !reflection.nested?
association_saved = association.insert_record(record)
if reflection.validate?
errors.add(reflection.name) unless association_saved
saved = association_saved
end
end
elsif autosave
saved = record.save(validate: false)
end
raise(RecordInvalid.new(association.owner)) unless saved
end
end
end
end
# Saves the associated record if it's new or :autosave is enabled
# on the association.
#
# In addition, it will destroy the association if it was marked for
# destruction with #mark_for_destruction.
#
# This all happens inside a transaction, _if_ the Transactions module is included into
# ActiveRecord::Base after the AutosaveAssociation module, which it does by default.
def save_has_one_association(reflection)
association = association_instance_get(reflection.name)
record = association && association.load_target
if record && !record.destroyed?
autosave = reflection.options[:autosave]
if autosave && record.marked_for_destruction?
record.destroy
elsif autosave != false
key = reflection.options[:primary_key] ? send(reflection.options[:primary_key]) : id
if (autosave && record.changed_for_autosave?) || new_record? || record_changed?(reflection, record, key)
unless reflection.through_reflection
record[reflection.foreign_key] = key
if inverse_reflection = reflection.inverse_of
record.association(inverse_reflection.name).loaded!
end
end
saved = record.save(validate: !autosave)
raise ActiveRecord::Rollback if !saved && autosave
saved
end
end
end
end
# If the record is new or it has changed, returns true.
def record_changed?(reflection, record, key)
record.new_record? ||
association_foreign_key_changed?(reflection, record, key) ||
record.will_save_change_to_attribute?(reflection.foreign_key)
end
def association_foreign_key_changed?(reflection, record, key)
return false if reflection.through_reflection?
record.has_attribute?(reflection.foreign_key) && record[reflection.foreign_key] != key
end
# Saves the associated record if it's new or :autosave is enabled.
#
# In addition, it will destroy the association if it was marked for destruction.
def save_belongs_to_association(reflection)
association = association_instance_get(reflection.name)
return unless association && association.loaded? && !association.stale_target?
record = association.load_target
if record && !record.destroyed?
autosave = reflection.options[:autosave]
if autosave && record.marked_for_destruction?
self[reflection.foreign_key] = nil
record.destroy
elsif autosave != false
saved = record.save(validate: !autosave) if record.new_record? || (autosave && record.changed_for_autosave?)
if association.updated?
association_id = record.send(reflection.options[:primary_key] || :id)
self[reflection.foreign_key] = association_id
association.loaded!
end
saved if autosave
end
end
end
def custom_validation_context?
validation_context && [:create, :update].exclude?(validation_context)
end
def _ensure_no_duplicate_errors
errors.messages.each_key do |attribute|
errors[attribute].uniq!
end
end
end
end