在一个有两个外键的模型与另一个模型之间创建一个关联

Question

与这个关联一起挣扎，我有两个模型：图和市场，您可以在其中与其他人交易您的玩具图。

Figure class 
    figure_id:integer 
    name  :string 
    image_url:string 

Market class 
    market_id:integer 
    figure_you_want_to_trade_id   :integer #this should be associated with the figure_id 
    figure_you_want_from_someone_else_id:integer #this should be associated with the figure_id 

我该如何去做这种关联？

我在想：

market.rb 
    has_many :figure_to_trade, :class_name => Figure, :foreign_key => figure_id 
    has_many :figure_you_want, :class_name => Figure, :foreign_key => figure_id 

figure.rb 
    belongs_to :figure_you_want_to_trade, :class_name => Market 
    belongs_to :figure_you_want_from_someone_else, :class_name => Market 

这是我收到的错误，当我试图输出这个：<％= market.figure_to_trade％>

的SQLite3 ::的SQLException：没有这样的柱：figures.figure_id：SELECT “人物” * FROM “人物” WHERE “人物”， “figure_id”= 1

Answer 1

想通了

market.rb 
    belongs_to :figure_you_want_to_trade, :class_name => Figure 
    belongs_to :figure_you_want_from_someone_else, :class_name => Figure 

figure.rb 
    has_many :figure_to_trade, :class_name => Market, :foreign_key => :figure_you_want_to_trade_id 
    has_many :figure_you_want, :class_name => Market, :foreign_key => :figure_you_want_from_someone_else_id 

。

然后我可以通过它（假设图类具有名称：字符串）

<% @markets.each do |market| %> 
    <%= market.figure_you_want_to_trade.name %> 
    <%= market.figure_you_want_from_someone_else.name %> 
<% end %>