1
我有這樣的聯想:如何從belongs_to關聯創建記錄?
user.rb
class User < ActiveRecord::Base
has_many :todo_lists
has_one :profile
end
todo_list.rb
class TodoList < ActiveRecord::Base
belongs_to :user
end
profile.rb
class Profile < ActiveRecord::Base
belongs_to :user
end
而且我想了解下行爲:
todo_list = TodoList.create(name: "list 1")
todo_list.create_user(username: "foo")
todo_list.user
#<User id: 1, username: "foo", created_at: "2016-05-01 07:09:05", updated_at: "2016-05-01 07:09:05">
test_user = todo_list.user
test_user.todo_lists # returns an empty list
=> #<ActiveRecord::Associations::CollectionProxy []>
test_user.todo_lists.create(name: "list 2")
test_user.todo_lists
=> #<ActiveRecord::Associations::CollectionProxy [#<TodoList id: 2, name: "list 2", user_id: 1, created_at: "2016-05-01 07:15:13", updated_at: "2016-05-01 07:15:13">]>
爲什麼#create_user
增加user
到todo_list
(todo_list.user
返回user
),但是當user.todo_lists
被稱爲沒有體現出聯想?
編輯:
試圖在一個one-to-one
關係創建從belongs_to
側的記錄使用#create_user!
時的作品。即使使用#create_user!
,在belongs_to
關聯中創建記錄時,它仍然不成立。
profile = Profile.create(first_name: "user_one")
profile.create_user!(username: "user_one username")
profile.user
=> #<User id: 6, username: "user_one username", created_at: "2016-05-01 18:22:31", updated_at: "2016-05-01 18:22:31">
user_one = profile.user
=> #<User id: 6, username: "user_one username", created_at: "2016-05-01 18:22:31", updated_at: "2016-05-01 18:22:31">
user_one.profile # the relationship was created
=> #<Profile id: 2, first_name: "user_one", user_id: 6, created_at: "2016-05-01 18:22:09", updated_at: "2016-05-01 18:22:31">
todo_list = TodoList.create(name: "a new list")
todo_list.create_user!(username: "user of a new list")
todo_list.user
=> #<User id: 7, username: "user of a new list", created_at: "2016-05-01 18:26:27", updated_at: "2016-05-01 18:26:27">
user_of_new_list = todo_list.user
=> #<User id: 7, username: "user of a new list", created_at: "2016-05-01 18:26:27", updated_at: "2016-05-01 18:26:27">
user_of_new_list.todo_lists #still does not create user from todo_list
=> #<ActiveRecord::Associations::CollectionProxy []>
使用'todo_list.save'確實有效。但爲什麼在關聯的另一端('user.todo_lists.create'),'user.save'沒有必要? – user3097405
這是沒有必要的另一方面,因爲,我認爲,'todo_list'創建像這樣的參數:'todo_list.create(user:user),我不確定細節,但在這個意思。 – kunashir
謝謝@kunashir,但它仍然沒有意義。我編輯了我的問題,將行爲與'一對一'關係進行比較。 – user3097405