Rails 4：无法更新多态对象

Question

My object Item has polymorphic association as element (It can be a video, texte etc.)

When I want to update the Item (and his element ) I do this :

@item.update_attributes(param_update_item)

I call this :

def param_update_item

  params.permit(:name, :visible, :title, element: [:content, :url, :html])

  # params.permit(:name, :visible, :title) # - don't get error, but obviously don't ubdate the element

end

the permitted params is good, but when the update_attributes is called, I get an error :

 undefined method `primary_key' for ActionController::Parameters:Class

Any idea?

EDIT :

class Item < ActiveRecord::Base
  belongs_to :element, :polymorphic => true, dependent: :destroy
end

module Element
  included do
    has_one :item, :as => :element, dependent: :destroy
  end
end

and an exemple of model (in my example)

class Texte < ActiveRecord::Base
  include Element

  validates :content, :presence => true
end

My Item in DB :

class Item < ActiveRecord::Base {
          :id => :integer,
          :element_id => :integer,
          :element_type => :string,
 ....  }

and when I do item.element I get :

 => <Texte id: 15757, content: "RE3  3232 /...", created_at: ...>

Answer 1

If you want to update your element with your item, you should tell the model that your item should accept nested attributes for element.

module Element
  included do
    has_one :item, :as => :element, dependent: :destroy
    accepts_nested_attributes_for :element 
  end
end

But I think you might have your relationships set up incorrectly. You say that you want your element to be polymorphic, but your item only belongs to element.

I would do

class Item < ActiveRecord::Base
  belongs_to :element
end
class Element < ActiveRecord::Base
  has_one :item
  belongs_to :elementable, polymorphic: true
  validates :content, presence: true
end
module Elementable
  extend ActiveSupport::Concern
  included do
    has_one :element, as: :elementable
    accepts_nested_attributes_for :element
  end
end
class Texte < ActiveRecord::Base
  include Elementable
end

Then in your item update, you can permit

element_attributes: [# all your element attributes in here]

This would require you to change the item table to have element_id and add elements table in a migration

create_table :elements do |t|
  t.belongs_to :elementable, polymorphic: true
end

This would create columns named elementable_type and elementable_id

I would read this for more info Polymorphic Associations