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module ActiveRecord
# AutosaveAssociation is a module that takes care of automatically saving
# your associations when the parent is saved. In addition to saving, it
# also destroys any associations 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 1 transaction. This should never leave the
# database in an inconsistent state after, for instance, mass assigning
# attributes and saving them.
#
# 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.
#
# === One-to-one Example
#
# Consider a Post model with one Author:
#
# class Post
# 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
#
# Consider a Post model with many Comments:
#
# class Post
# has_many :comments, :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.comments.first.body # => "Wow, awesome info thanks!"
# post.comments.last.body # => "Actually, your article should be named differently."
#
# post.title = "On the migration of ducks"
# post.comments.last.body = "Actually, your article should be named differently. [UPDATED]: You are right, thanks."
#
# post.save
# post.reload
# post.title # => "On the migration of ducks"
# post.comments.last.body # => "Actually, your article should be named differently. [UPDATED]: You are right, thanks."
#
# Destroying one of the associated models members, as part of the parent's
# save action, is as simple as marking it for destruction:
#
# post.comments.last.mark_for_destruction
# post.comments.last.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
#
# === Validation
#
# Validation is performed on the parent as usual, but also on all autosave
# enabled associations. If any of the associations fail validation, its
# error messages will be applied on the parents errors object and validation
# of the parent will fail.
#
# Consider a Post model with Author which validates the presence of its name
# attribute:
#
# class Post
# has_one :author, :autosave => true
# end
#
# class Author
# validates_presence_of :name
# end
#
# post = Post.find(1)
# post.author.name = ''
# post.save # => false
# post.errors # => #<ActiveRecord::Errors:0x174498c @errors={"author_name"=>["can't be blank"]}, @base=#<Post ...>>
#
# No validations will be performed on the associated models when validations
# are skipped for the parent:
#
# post = Post.find(1)
# post.author.name = ''
# post.save(false) # => true
module AutosaveAssociation
ASSOCIATION_TYPES = %w{ has_one belongs_to has_many has_and_belongs_to_many }
def self.included(base)
base.class_eval do
base.extend(ClassMethods)
alias_method_chain :reload, :autosave_associations
ASSOCIATION_TYPES.each do |type|
base.send("valid_keys_for_#{type}_association") << :autosave
end
end
end
module ClassMethods
private
# def belongs_to(name, options = {})
# super
# add_autosave_association_callbacks(reflect_on_association(name))
# end
ASSOCIATION_TYPES.each do |type|
module_eval <<-CODE, __FILE__, __LINE__ + 1
def #{type}(name, options = {})
super
add_autosave_association_callbacks(reflect_on_association(name))
end
CODE
end
# Adds a validate and save callback for the association as specified by
# the +reflection+.
#
# For performance reasons, we don't check whether to validate at runtime,
# but instead only define the method and callback when needed. 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}"
validation_method = :"validate_associated_records_for_#{reflection.name}"
collection = reflection.collection?
unless method_defined?(save_method)
if collection
before_save :before_save_collection_association
define_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
else
if reflection.macro == :has_one
define_method(save_method) { save_has_one_association(reflection) }
after_save save_method
else
define_method(save_method) { save_belongs_to_association(reflection) }
before_save save_method
end
end
end
if reflection.validate? && !method_defined?(validation_method)
method = (collection ? :validate_collection_association : :validate_single_association)
define_method(validation_method) { send(method, reflection) }
validate validation_method
end
end
end
# Reloads the attributes of the object as usual and removes a mark for destruction.
def reload_with_autosave_associations(options = nil)
@marked_for_destruction = false
reload_without_autosave_associations(options)
end
# Marks this record to be destroyed as part of the parents save transaction.
# This does _not_ actually destroy the record yet, rather it will be destroyed when <tt>parent.save</tt> is called.
#
# Only useful if the <tt>:autosave</tt> 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 parents save transaction.
#
# Only useful if the <tt>:autosave</tt> option on the parent is enabled for this associated model.
def marked_for_destruction?
@marked_for_destruction
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? || changed? || 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
association
elsif autosave
association.target.select { |record| record.changed_for_autosave? }
else
association.target.select { |record| record.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?
self.class.reflect_on_all_autosave_associations.each do |reflection|
if association = association_instance_get(reflection.name)
if [:belongs_to, :has_one].include?(reflection.macro)
return true if association.target && association.target.changed_for_autosave?
else
association.target.each {|record| return true if record.changed_for_autosave? }
end
end
end
false
end
# Validate the association if <tt>:validate</tt> or <tt>:autosave</tt> is
# turned on for the association specified by +reflection+.
def validate_single_association(reflection)
if (association = association_instance_get(reflection.name)) && !association.target.nil?
association_valid?(reflection, association)
end
end
# Validate the associated records if <tt>:validate</tt> or
# <tt>:autosave</tt> 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 { |record| association_valid?(reflection, record) }
end
end
end
# Returns whether or not the association is valid and applies any errors to
# the parent, <tt>self</tt>, if it wasn't. Skips any <tt>:autosave</tt>
# enabled records if they're marked_for_destruction? or destroyed.
def association_valid?(reflection, association)
return true if association.destroyed? || association.marked_for_destruction?
unless valid = association.valid?
if reflection.options[:autosave]
association.errors.each_error do |attribute, error|
attribute = "#{reflection.name}.#{attribute}"
errors.add(attribute, error.dup) unless errors.on(attribute)
end
else
errors.add(reflection.name)
end
end
valid
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?
true
end
# Saves any new associated records, or all loaded autosave associations if
# <tt>:autosave</tt> 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]
if records = associated_records_to_validate_or_save(association, @new_record_before_save, autosave)
records.each do |record|
next if record.destroyed?
if autosave && record.marked_for_destruction?
association.destroy(record)
elsif autosave != false && (@new_record_before_save || record.new_record?)
if autosave
saved = association.send(:insert_record, record, false, false)
else
association.send(:insert_record, record)
end
elsif autosave
saved = record.save(false)
end
raise ActiveRecord::Rollback if saved == false
end
end
# reconstruct the SQL queries now that we know the owner's id
association.send(:construct_sql) if association.respond_to?(:construct_sql)
end
end
# Saves the associated record if it's new or <tt>:autosave</tt> 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)
if (association = association_instance_get(reflection.name)) && !association.target.nil? && !association.destroyed?
autosave = reflection.options[:autosave]
if autosave && association.marked_for_destruction?
association.destroy
else
key = reflection.options[:primary_key] ? send(reflection.options[:primary_key]) : id
if autosave != false && (new_record? || association.new_record? || association[reflection.primary_key_name] != key || autosave)
association[reflection.primary_key_name] = key
saved = association.save(!autosave)
raise ActiveRecord::Rollback if !saved && autosave
saved
end
end
end
end
# Saves the associated record if it's new or <tt>:autosave</tt> 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_belongs_to_association(reflection)
if (association = association_instance_get(reflection.name)) && !association.destroyed?
autosave = reflection.options[:autosave]
if autosave && association.marked_for_destruction?
association.destroy
elsif autosave != false
saved = association.save(!autosave) if association.new_record? || autosave
if association.updated?
association_id = association.send(reflection.options[:primary_key] || :id)
self[reflection.primary_key_name] = association_id
# TODO: Removing this code doesn't seem to matter…
if reflection.options[:polymorphic]
self[reflection.options[:foreign_type]] = association.class.base_class.name.to_s
end
end
saved if autosave
end
end
end
end
end
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