From ec8f04584479aff895b0b511a7ba1e9d33f84067 Mon Sep 17 00:00:00 2001 From: Eloy Duran Date: Sun, 1 Feb 2009 14:44:30 +1300 Subject: Add support for nested object forms to ActiveRecord and the helpers in ActionPack Signed-Off-By: Michael Koziarski [#1202 state:committed] --- .../lib/active_record/nested_attributes.rb | 279 +++++++++++++++++++++ 1 file changed, 279 insertions(+) create mode 100644 activerecord/lib/active_record/nested_attributes.rb (limited to 'activerecord/lib/active_record/nested_attributes.rb') diff --git a/activerecord/lib/active_record/nested_attributes.rb b/activerecord/lib/active_record/nested_attributes.rb new file mode 100644 index 0000000000..8bfdadd0e3 --- /dev/null +++ b/activerecord/lib/active_record/nested_attributes.rb @@ -0,0 +1,279 @@ +module ActiveRecord + module NestedAttributes #:nodoc: + def self.included(base) + base.extend(ClassMethods) + base.class_inheritable_accessor :reject_new_nested_attributes_procs, :instance_writer => false + base.reject_new_nested_attributes_procs = {} + end + + # == Nested Attributes + # + # Nested attributes allow you to save attributes on associated records + # through the parent. By default nested attribute updating is turned off, + # you can enable it using the accepts_nested_attributes_for class method. + # When you enable nested attributes an attribute writer is defined on + # the model. + # + # The attribute writer is named after the association, which means that + # in the following example, two new methods are added to your model: + # author_attributes=(attributes) and + # pages_attributes=(attributes). + # + # class Book < ActiveRecord::Base + # has_one :author + # has_many :pages + # + # accepts_nested_attributes_for :author, :pages + # end + # + # Note that the :autosave option is automatically enabled on every + # association that accepts_nested_attributes_for is used for. + # + # === One-to-one + # + # Consider a Member model that has one Avatar: + # + # class Member < ActiveRecord::Base + # has_one :avatar + # accepts_nested_attributes_for :avatar + # end + # + # Enabling nested attributes on a one-to-one association allows you to + # create the member and avatar in one go: + # + # params = { 'member' => { 'name' => 'Jack', 'avatar_attributes' => { 'icon' => 'smiling' } } } + # member = Member.create(params) + # member.avatar.icon #=> 'smiling' + # + # It also allows you to update the avatar through the member: + # + # params = { 'member' => { 'avatar_attributes' => { 'icon' => 'sad' } } } + # member.update_attributes params['member'] + # member.avatar.icon #=> 'sad' + # + # By default you will only be able to set and update attributes on the + # associated model. If you want to destroy the associated model through the + # attributes hash, you have to enable it first using the + # :allow_destroy option. + # + # class Member < ActiveRecord::Base + # has_one :avatar + # accepts_nested_attributes_for :avatar, :allow_destroy => true + # end + # + # Now, when you add the _delete key to the attributes hash, with a + # value that evaluates to +true+, you will destroy the associated model: + # + # member.avatar_attributes = { '_delete' => '1' } + # member.avatar.marked_for_destruction? # => true + # member.save + # member.avatar #=> nil + # + # Note that the model will _not_ be destroyed until the parent is saved. + # + # === One-to-many + # + # Consider a member that has a number of posts: + # + # class Member < ActiveRecord::Base + # has_many :posts + # accepts_nested_attributes_for :posts, :reject_if => proc { |attributes| attributes['title'].blank? } + # end + # + # You can now set or update attributes on an associated post model through + # the attribute hash. + # + # For each key in the hash that starts with the string 'new' a new model + # will be instantiated. When the proc given with the :reject_if + # option evaluates to +false+ for a certain attribute hash no record will + # be built for that hash. + # + # params = { 'member' => { + # 'name' => 'joe', 'posts_attributes' => { + # 'new_12345' => { 'title' => 'Kari, the awesome Ruby documentation browser!' }, + # 'new_54321' => { 'title' => 'The egalitarian assumption of the modern citizen' }, + # 'new_67890' => { 'title' => '' } # This one matches the :reject_if proc and will not be instantiated. + # } + # }} + # + # member = Member.create(params['member']) + # member.posts.length #=> 2 + # member.posts.first.title #=> 'Kari, the awesome Ruby documentation browser!' + # member.posts.second.title #=> 'The egalitarian assumption of the modern citizen' + # + # When the key for post attributes is an integer, the associated post with + # that ID will be updated: + # + # member.attributes = { + # 'name' => 'Joe', + # 'posts_attributes' => { + # '1' => { 'title' => '[UPDATED] An, as of yet, undisclosed awesome Ruby documentation browser!' }, + # '2' => { 'title' => '[UPDATED] other post' } + # } + # } + # + # By default the associated models are protected from being destroyed. If + # you want to destroy any of the associated models through the attributes + # hash, you have to enable it first using the :allow_destroy + # option. + # + # This will allow you to specify which models to destroy in the attributes + # hash by setting the '_delete' attribute to a value that evaluates to + # +true+: + # + # class Member < ActiveRecord::Base + # has_many :posts + # accepts_nested_attributes_for :posts, :allow_destroy => true + # end + # + # params = {'member' => { 'name' => 'joe', 'posts_attributes' => { + # '2' => { '_delete' => '1' } + # }}} + # member.attributes = params['member'] + # member.posts.detect { |p| p.id == 2 }.marked_for_destruction? # => true + # member.posts.length #=> 2 + # member.save + # member.posts.length # => 1 + # + # === Saving + # + # All changes to models, including the destruction of those marked for + # destruction, are saved and destroyed automatically and atomically when + # the parent model is saved. This happens inside the transaction initiated + # by the parents save method. See ActiveRecord::AutosaveAssociation. + module ClassMethods + # Defines an attributes writer for the specified association(s). + # + # Supported options: + # [:allow_destroy] + # If true, destroys any members from the attributes hash with a + # _delete key and a value that converts to +true+ + # (eg. 1, '1', true, or 'true'). This option is off by default. + # [:reject_if] + # Allows you to specify a Proc that checks whether a record should be + # built for a certain attribute hash. The hash is passed to the Proc + # and the Proc should return either +true+ or +false+. When no Proc + # is specified a record will be built for all attribute hashes. + # + # Examples: + # accepts_nested_attributes_for :avatar + # accepts_nested_attributes_for :avatar, :allow_destroy => true + # accepts_nested_attributes_for :avatar, :reject_if => proc { ... } + # accepts_nested_attributes_for :avatar, :posts, :allow_destroy => true, :reject_if => proc { ... } + def accepts_nested_attributes_for(*attr_names) + options = { :allow_destroy => false } + options.update(attr_names.extract_options!) + options.assert_valid_keys(:allow_destroy, :reject_if) + + attr_names.each do |association_name| + if reflection = reflect_on_association(association_name) + type = case reflection.macro + when :has_one, :belongs_to + :one_to_one + when :has_many, :has_and_belongs_to_many + :collection + end + + reflection.options[:autosave] = true + self.reject_new_nested_attributes_procs[association_name.to_sym] = options[:reject_if] + + # def pirate_attributes=(attributes) + # assign_nested_attributes_for_one_to_one_association(:pirate, attributes, false) + # end + class_eval %{ + def #{association_name}_attributes=(attributes) + assign_nested_attributes_for_#{type}_association(:#{association_name}, attributes, #{options[:allow_destroy]}) + end + }, __FILE__, __LINE__ + else + raise ArgumentError, "No association found for name `#{association_name}'. Has it been defined yet?" + end + end + end + end + + # Returns ActiveRecord::AutosaveAssociation::marked_for_destruction? + # It's used in conjunction with fields_for to build a form element + # for the destruction of this association. + # + # See ActionView::Helpers::FormHelper::fields_for for more info. + def _delete + marked_for_destruction? + end + + private + + # Assigns the given attributes to the association. An association will be + # build if it doesn't exist yet. + def assign_nested_attributes_for_one_to_one_association(association_name, attributes, allow_destroy) + if should_destroy_nested_attributes_record?(allow_destroy, attributes) + send(association_name).mark_for_destruction + else + (send(association_name) || send("build_#{association_name}")).attributes = attributes + end + end + + # Assigns the given attributes to the collection association. + # + # Keys containing an ID for an associated record will update that record. + # Keys starting with new will instantiate a new record for that + # association. + # + # For example: + # + # assign_nested_attributes_for_collection_association(:people, { + # '1' => { 'name' => 'Peter' }, + # 'new_43' => { 'name' => 'John' } + # }) + # + # Will update the name of the Person with ID 1 and create a new associated + # person with the name 'John'. + def assign_nested_attributes_for_collection_association(association_name, attributes, allow_destroy) + unless attributes.is_a?(Hash) + raise ArgumentError, "Hash expected, got #{attributes.class.name} (#{attributes.inspect})" + end + + # Make sure any new records sorted by their id before they're build. + sorted_by_id = attributes.sort_by { |id, _| id.is_a?(String) ? id.sub(/^new_/, '').to_i : id } + + sorted_by_id.each do |id, record_attributes| + if id.acts_like?(:string) && id.starts_with?('new_') + build_new_nested_attributes_record(association_name, record_attributes) + else + assign_to_or_destroy_nested_attributes_record(association_name, id, record_attributes, allow_destroy) + end + end + end + + # Returns +true+ if allow_destroy is enabled and the attributes + # contains a truthy value for the key '_delete'. + # + # It will _always_ remove the '_delete' key, if present. + def should_destroy_nested_attributes_record?(allow_destroy, attributes) + ConnectionAdapters::Column.value_to_boolean(attributes.delete('_delete')) && allow_destroy + end + + # Builds a new record with the given attributes. + # + # If a :reject_if proc exists for this association, it will be + # called with the attributes as its argument. If the proc returns a truthy + # value, the record is _not_ build. + def build_new_nested_attributes_record(association_name, attributes) + if reject_proc = self.class.reject_new_nested_attributes_procs[association_name] + return if reject_proc.call(attributes) + end + send(association_name).build(attributes) + end + + # Assigns the attributes to the record specified by +id+. Or marks it for + # destruction if #should_destroy_nested_attributes_record? returns +true+. + def assign_to_or_destroy_nested_attributes_record(association_name, id, attributes, allow_destroy) + record = send(association_name).detect { |record| record.id == id.to_i } + if should_destroy_nested_attributes_record?(allow_destroy, attributes) + record.mark_for_destruction + else + record.attributes = attributes + end + end + end +end \ No newline at end of file -- cgit v1.2.3