Rails 多对多，条件添加新条件

Question

我用“喜欢”和“推荐”来建模用户和电影。

模型如下：

class Movie < ActiveRecord::Base
  attr_accessible :title, :imbd_id

  has_and_belongs_to_many :liked_by, :class_name => "User", 
    :conditions => { "type" => "like" }
  has_and_belongs_to_many :recommended_by, :class_name => "User", 
    :conditions => { "type" => "recommend" }

end

class User < ActiveRecord::Base

  has_and_belongs_to_many :movies_liked, :class_name => "Movie", 
    :conditions => { "type" => "like" }
  has_and_belongs_to_many :movies_recommended, :class_name => "Movie", 
    :conditions => { "type" => "recommend" }

end

用一个表来映射关系：

 create_table "movies_users", :id => false, :force => true do |t|
    t.integer  "user_id"
    t.integer  "movie_id"
    t.string   "type"           # this can be "like" or "recommend"
    t.string   "status_id"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

现在，当我尝试处理

u = User.first
m = Movie.first
u.movie_liked << m 

以下错误

ruby-1.9.2-p290 :003 > u.movies_tweeted << m 
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: movies.type: SELECT * FROM "movies" INNER JOIN "movies_users" ON "movies".id = "movies_users".movie_id WHERE ("movies_users".user_id = 1  AND ("movies"."type" = 'like'))

时，我收到一个错误任何想法我都可以很好地构造它，这样我就可以使用 <<运算符并且它会自动分配正确的类型？

谢谢！

Answer 1

您可以创建推荐和点赞模型，并使用它们加入电影用户。或者只是一个名为“不知道如何”的模型（RecommendLike？），如果您确实希望保存在一张桌子上。进而：

User
  has_many :recommendations
  has_many :movies_recommended, :class_name => "Movie", :through => :recommendations
  has_many :likes
  has_many :movies_liked, :class_name => "Movie", :through => :likes