ActiveRecord は、ネストされた属性を持つ既存のレコードのパラメーターのセットが与えられると、それ自体がネストされた既存のレコードを持つ新しいネストされたレコードを作成できることを理解していないようです。(関係ツリー: Existing -> New -> Existing)
これはバグですか、それとも何か不足していますか?
簡単な例をお見せしましょう。
ここに私のモデルがあります：
class User < ActiveRecord::Base
has_many :posts
attr_accessible :name, :posts_attributes
accepts_nested_attributes_for :posts
end
class Post < ActiveRecord::Base
belongs_to :group
belongs_to :user
attr_accessible :content, :title, :group_attributes
accepts_nested_attributes_for :group
end
class Group < ActiveRecord::Base
has_many :posts
attr_accessible :name
end
各テーブルに 1 つのレコードを作成し、それに応じて関連付けたので、各テーブルにはid=1--this が既知のレコードが含まれています。ここで、既存のユーザー、新しい投稿、および既存のグループがあり、 を使用してそのレコードを更新しようとするとaccepts_nested_attributes_for、気に入らない:
1.9.3-p125 :044 > params
{
:id => 1,
:name => "Billy",
:posts_attributes => [
[0] {
:title => "Title",
:content => "Some magnificent content for you!",
:group_attributes => {
:id => 1,
:name => "Group 1"
}
}
]
}
1.9.3-p125 :045 > u
#<User:0x00000002f7f380> {
:id => 1,
:name => "Billy",
:created_at => Fri, 03 Aug 2012 20:21:37 UTC +00:00,
:updated_at => Fri, 03 Aug 2012 20:21:37 UTC +00:00
}
1.9.3-p125 :046 > u.update_attributes params
(0.1ms) begin transaction
(0.1ms) rollback transaction
ActiveRecord::RecordNotFound: Couldn't find Group with ID=1 for Post with ID=
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/nested_attributes.rb:462:in `raise_nested_attributes_record_not_found'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/nested_attributes.rb:332:in `assign_nested_attributes_for_one_to_one_association'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/nested_attributes.rb:288:in `group_attributes='
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/attribute_assignment.rb:94:in `block in assign_attributes'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/attribute_assignment.rb:93:in `each'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/attribute_assignment.rb:93:in `assign_attributes'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/base.rb:498:in `initialize'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/reflection.rb:183:in `new'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/reflection.rb:183:in `build_association'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/associations/association.rb:233:in `build_record'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/associations/collection_association.rb:112:in `build'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/nested_attributes.rb:405:in `block in assign_nested_attributes_for_collection_association'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/nested_attributes.rb:400:in `each'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/nested_attributes.rb:400:in `assign_nested_attributes_for_collection_association'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/nested_attributes.rb:288:in `posts_attributes='
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/attribute_assignment.rb:85:in `block in assign_attributes'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/attribute_assignment.rb:78:in `each'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/attribute_assignment.rb:78:in `assign_attributes'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/persistence.rb:216:in `block in update_attributes'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/transactions.rb:295:in `block in with_transaction_returning_status'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/connection_adapters/abstract/database_statements.rb:192:in `transaction'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/transactions.rb:208:in `transaction'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/transactions.rb:293:in `with_transaction_returning_status'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.7/lib/active_record/persistence.rb:215:in `update_attributes'
from (irb):15
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/railties-3.2.7/lib/rails/commands/console.rb:47:in `start'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/railties-3.2.7/lib/rails/commands/console.rb:8:in `start'
from /home/trevor/.rvm/gems/ruby-1.9.3-p125/gems/railties-3.2.7/lib/rails/commands.rb:41:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'1.9.3-p125 :047 >
新しい投稿に関連する (既知の ID を持つ) グループが見つからないと考えます。から ID を削除すると機能しますgroup_attributes(ただし、新しいグループ レコードが作成されます)。ID を指定しposts_attributes、ID を削除すると機能group_attributesします (また、新しいグループを作成します)。また、全員が ID を持っている場合にも機能します。
関係は機能しています：
1.9.3-p125 :059 > p = Post.new( { group_attributes: { name: 'Testing' } } )
#<Post:0x00000004212380> {
:id => nil,
:title => nil,
:content => nil,
:group_id => nil,
:user_id => nil,
:created_at => nil,
:updated_at => nil
}
1.9.3-p125 :060 > p.group
[
[0] #<Group:0x00000004211868> {
:id => nil,
:name => "Testing",
:created_at => nil,
:updated_at => nil
}
]
すべてのレコードが新しい場合、使用中posts_attributesおよび作成中にも完全に機能します。group_attributesUser
最初の例ではまだ動作するはずではありませんか? ActiveRecordはこれを理解するのに十分賢いはずです...!