ruby-on-rails - 使用 has_many :through and build

Question

我有三个模型，都用于 has_many :through 关系。它们看起来像这样:

class Company < ActiveRecord::Base

  has_many :company_users, dependent: :destroy
  has_many :users, through: :company_users

  accepts_nested_attributes_for :company_users, :users

end

class CompanyUser < ActiveRecord::Base
  self.table_name = :companies_users #this is because this was originally a habtm relationship
  belongs_to :company
  belongs_to :user
end

class User < ActiveRecord::Base
  # this is a devise model, if that matters

  has_many :company_users, dependent: :destroy
  has_many :companies, through: :company_users

  accepts_nested_attributes_for :company_users, :companies

end

这加载很好，并且连接是为查询而构建的。但是，每当我做类似的事情时

@company = Company.last
@user = @company.users.build(params[:user])

@user.save    #=> true
@company.save #=> true

User记录和 CompanyUser记录被创建，但是 company_id CompanyUser 中的字段记录设置为 NULL

INSERT INTO `companies_users` (`company_id`, `created_at`,`updated_at`, `user_id`) 
VALUES (NULL, '2012-02-19 02:09:04', '2012-02-19 02:09:04', 18)

当你 @company.users << @user 时它做同样的事情

我确定我在这里做了一些愚蠢的事情，我只是不知道是什么。

Answer 1

你不能像那样使用has_many :through，你必须这样做:

@company = Company.last
@user    = User.create( params[:user] ) 
@company.company_users.create( :user_id => @user.id )

然后您将正确定义关联。

更新

在下面的评论中，因为您已经有了 accepts_nested_attributes_for，所以您的参数必须像这样:

{ :company => 
    { :company_users_attributes => 
        [ 
          { :company_id => 1, :user_id => 1 } ,
          { :company_id => 1, :user_id => 2 },
          { :company_id => 1, :user_id => 3 } 
        ]
    } 
}

并且您会自动为您将用户添加到公司。