[英]How to join the same 2 models twice in Rails 4.0?
我在軌道4上,我不知道如何在軌道上兩次加入兩個模型。 我在這里找到了解決問題的答案,但這是一個古老的答案,它的含義是:
class User < ActiveRecord::Base
has_many :user_countries
has_many :event_countries,
:through => :user_countries,
:source => :country,
:conditions => { :event => true }
has_many :research_countries,
:through => :user_countries,
:source => :country,
:conditions => { :research => true }
end
class UserCountry < ActiveRecord::Base
belongs_to :country
belongs_to :user
# * column :event, :boolean
# * column :research, :boolean
end
class Country < ActiveRecord::Base
# ...
end
我發現此解決方案很有趣,因為我僅需要一個UserCountries聯接表,但是它似乎在rails 4中不起作用( 條件方法在rails 4.0中已棄用 ),所以我的問題很簡單:您將如何在中執行此操作導軌4.0?
您提到的解決方案仍然有效,您只需要更改條件部分即可采用新的Rails 4約定(請參見此處的類似問題 ):
class User < ActiveRecord::Base
has_many :user_countries
has_many :event_countries,
-> { where(user_countries: {:event => true}) },
:through => :user_countries,
:source => :country
has_many :research_countries,
-> { where(user_countries: {:research => true}) },
:through => :user_countries
:source => :country
end
class UserCountry < ActiveRecord::Base
belongs_to :country
belongs_to :user
end
class Country < ActiveRecord::Base
# ...
end
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