Question

我有一张用户表和一张礼品表。用户可以为他们的朋友挑选礼物。我正在考虑创建一个表来存储用户ID和礼物ID，以跟踪哪个用户选择了哪个礼物给谁。如何建立这种关系？我认为用户和礼物有HABTM关系。是吗？

Answer 1

试试这个：

class User < ActiveRecord::Base
  has_many :user_gifts
  has_many :gifts, :through => :user_gifts  

  has_many :rcvd_user_gifts, :class_name =>"UserGift", :foreign_key => :friend_id
  has_many :rcvd_gifts, :through => :rcvd_user_gifts, :source => :gift
end

class UserGift < ActiveRecord::Base
  # user_id
  # friend_id
  # gift_id

  belongs_to :user
  belongs_to :friend, :class_name => "User"
  belongs_to :gift

end

class Gift < ActiveRecord::Base
  has_many :user_gifts
  has_many :senders, :through => :user_gifts, :source => :user
  has_many :receivers, :through => :user_gifts, :source => :friend
end

现在可以跟随电话：

user.gifts      # Gifts given by a user:
user.rcvd_gifts # Gifts received by a user:
gift.senders    # Users sending a gift
gift.receivers  # Users receiving a gift

确保您为user_id表格中的friend_id，gift_id，user_gifts列编制索引。

Answer 2

嗯，首先，它是一个三向关系，因为你有用户 - ＆gt;朋友，以及用户 - ＆gt;礼品。

我会选择has_many：通过并存储朋友的ID。查询会有点尴尬，但它应该有效。

Rails关系建模

2 个答案: