有很多：通過關聯：無法批量分配受保護的屬性：model_id？

Question

我試圖創建我的狗，並添加類別，但我得到的錯誤：

WARNING: Can't mass-assign protected attributes: category_id 
    SQL (49.0ms) INSERT INTO "categorizations" ("dog_id", "category_id", "created_at", "cat_id", "mouse_id", "updated_at") VALUES ($1, $2, $3, $4, $5, $6) RETURNING "id" [["dog_id", 7], ["category_id", 1], ["created_at", Sun, 29 Jul 2012 20:34:27 JST +09:00], ["cat_id", nil], ["mouse_id", nil], ["updated_at", Sun, 29 Jul 2012 20:34:27 JST +09:00]] 
    (105.0ms) COMMIT 
Completed 500 Internal Server Error in 669ms 

ArgumentError (too few arguments): 
    app/controllers/dogs_controller.rb:7:in `format' 
    app/controllers/dogs_controller.rb:7:in `create' 

不知道爲什麼這是真的，因爲我在我的模型：

class Dog < ActiveRecord::Base 
    attr_accessible :name, :category_ids 
    belongs_to :user 
    has_many :categorizations 
    has_many :categories, :through => :categorizations 
    accepts_nested_attributes_for :categories 
    validates :name, :presence => true 
    validates :user_id, :presence => true 
end 

正如你所看到的連接表是Categorizations：

class Categorization < ActiveRecord::Base 
    belongs_to :dog 
    belongs_to :category 
    belongs_to :cat 
    belongs_to :mouse 
end 

我選擇所需的表格上的類別。這裏的模型：

class Category < ActiveRecord::Base 
    attr_accessible :name 
    belongs_to :user 
    has_many :categorizations 
    has_many :dogs, :through => :categorizations 
    has_many :cats, :through => :categorizations 
    has_many :mouses, :through => :categorizations 
    validates :name, :presence => true, :uniqueness => true 
    before_validation :downcase_name 

    private 
    def downcase_name 
    self.name = self.name.downcase if self.name.present? 
    end 
end 

對於希望在數據庫的時候，但是這可能會導致我有其他問題，但它仍然分配類別一些奇怪的原因。可能是什麼問題呢？

UPDATE

這裏是我的狗的形式：

<%= form_for(@dog, :remote => true) do |f| %> 
    <%= f.label :name, "Name" %> 
    <%= f.text_field :name %> 
    <%= f.label :category, "Categories" %> 
    <%= f.select :category_ids, Category.all.collect {|c| [c.name, c.id]}, {}, { :multiple => true, } %> 
<% end %> 

仍然得到大衆分配錯誤，當我嘗試：

attr_accessible :name, :category_ids 
WARNING: Can't mass-assign protected attributes: category_id 

attr_accessible :name, :category_id, :category_ids 
# It says this for each category I want to put on the Dog. 
WARNING: Can't mass-assign protected attributes: category_id 

attr_accessible :name, :category_id 
WARNING: Can't mass-assign protected attributes: category_ids 

更新2

我能得到通過添加respond_to針對控制器動作雖然擺脫引發ArgumentError的：

def create 
    @dog = current_user.dogs.new(params[:dog]) 
    respond_to do |format| 
     if @dog.save 
     format.js 
     else 
     format.js 
     end 
    end 
end 

如果增加2個或多個類別的犬（在這種情況下3）。它增加了他們在數據庫中，並指派質量，但他們的服務器口口聲聲說此日誌中：

Started POST "/dogs" for 127.0.0.1 at 2012-07-29 20:44:15 -0400 
    Processing by DogsController#create as JS 
    Parameters: {"utf8"=>"Γ£ô", "authenticity_token"=>"wuPqA6e8MqF/yW3VQ+sfLiyf0olOWgEpnVC2qawQE0I=", "dog" 
Add Dog"} 
    User Load (2.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = 1 LIMIT 1 
    Category Load (0.0ms) SELECT "categories".* FROM "categories" WHERE "categories"."id" IN (1, 2, 3) 
    (1.0ms) BEGIN 
    (0.0ms) COMMIT 
    (0.0ms) BEGIN 
    (1.0ms) SELECT 1 FROM "categories" WHERE ("categories"."name" = 'furry' AND "categories"."id" != 1) LI 
    (1.0ms) SELECT 1 FROM "categories" WHERE ("categories"."name" = 'house trained' AND "categories"."id" != 2) LIMIT                   
    (0.0ms) SELECT 1 FROM "categories" WHERE ("categories"."name" = 'wild' AND "categories"."id" != 3) LIMIT 
    SQL (1.0ms) INSERT INTO "dogs" ("created_at", "name", "updated_at", "user_id") VALUES ($1, $2, $3, $4                   
"name", "Omni Dog"], ["updated_at", Mon, 30 Jul 2012 09:44:15 JST +09:00], ["user_id", 1]] 

WARNING: Can't mass-assign protected attributes: category_id 
    [1m[35mSQL (1.0ms)[0m INSERT INTO "categorizations" ("dog_id", "category_id", "created_at", "cat_id", "mouse_id", "updated_at") VALUES ($1, $2, $3, $4, $5, $6) RETURNING "id" [["dog_id", 31], ["category_id", 1], ["created_at", Mon, 30 Jul 2012 09:44:15 JST +09:00], ["cat__id", nil], ["mouse_id", nil], ["updated_at", Mon, 30 Jul 2012 09:44:15 JST +09:00]] 

WARNING: Can't mass-assign protected attributes: category_id 
    [1m[36mSQL (1.0ms)[0m [1mINSERT INTO "categorizations" ("dog_id", "category_id", "created_at", "cat__id", "mouse_id", "updated_at") VALUES ($1, $2, $3, $4, $5, $6) RETURNING "id"[0m [["dog_id", 31], ["category_id", 2], ["created_at", Mon, 30 Jul 2012 09:44:16 JST +09:00], ["cat__id", nil], ["mouse_id", nil], ["updated_at", Mon, 30 Jul 2012 09:44:16 JST +09:00]] 

WARNING: Can't mass-assign protected attributes: category_id 
    [1m[35mSQL (1.0ms)[0m INSERT INTO "categorizations" ("dog_id", "category_id", "created_at", "cat__id", "mouse_id", "updated_at") VALUES ($1, $2, $3, $4, $5, $6) RETURNING "id" [["dog_id", 31], ["category_id", 3], ["created_at", Mon, 30 Jul 2012 09:44:16 JST +09:00], ["cat__id", nil], ["mouse_id", nil], ["updated_at", Mon, 30 Jul 2012 09:44:16 JST +09:00]] 

Rendered dogs/_dog.html.erb (1.0ms) 
Rendered dogs/create.js.erb (3.0ms) 
Completed 200 OK in 203ms (Views: 25.0ms | ActiveRecord: 52.0ms) 

這是一個問題，如果它在技術上的工作？

Answer 1

我需要改變這樣的：

@dog = current_user.dogs.new(params[:dog]) 

去此地：

@dog = current_user.dogs.build(params[:dog]) 

然後它開始爲我工作。

Answer 2

你有一個額外s這裏：

class Dog < ActiveRecord::Base 
    attr_accessible :name, :category_ids 
    ... 

category_id是在dogs表中的列，所以，只是將其刪除：

class Dog < ActiveRecord::Base 
    attr_accessible :name, :category_id