How to join the same 2 models twice in Rails 4.0?

Question

I'm on rails 4 and I couldn't figure out how to join two models twice in rails. I found an answer to my problem here but it's an old one, here's what it says:

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

I found this solution interesting as I only need one join table for UserCountries, however it doesn't seem to work in rails 4 (the conditions method has been deprecated in rails 4.0), so my question is simply : how would you do this in rails 4.0 ?

score 2 · Accepted Answer · edited May 23 '17 at 12:20

2

The solution you mention is still valid, you just need to change the conditions part to adopt the new Rails 4 convention (see similar question here):

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

edited May 23 '17 at 12:20

Community

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1

answered Dec 15 '14 at 21:15

dgilperez

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Thanks a lot for your answer however it looks like it tried to get the event column in the countries table: SQLite3::SQLException: no such column: countries.event: SELECT "countries".* FROM "countries" INNER JOIN "user_countries" ON "countries"."id" = "user_countries"."country_id" WHERE "countries"."event" = 't' AND "user_countries"."user_id" = ? – Badr Tazi Dec 15 '14 at 22:11
Indeed there are two things missing in your answer: - -> { where(user_countries: { event: true } } - :source => country – Badr Tazi Dec 15 '14 at 22:22
This is working: 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 You can edit so that I can accept it :) – Badr Tazi Dec 15 '14 at 22:25
@Badoo thanks for testing it, I wrote it from the top of my head. Code fixed. Glad to help! – dgilperez Dec 16 '14 at 12:47

How to join the same 2 models twice in Rails 4.0?

1 Answers1