How can I create a join without sql code in rails? - ruby-on-rails

Question

I can't make a join in rails, I don't know what is wrong here. my classes are:
class Serie < ActiveRecord::Base
has_many :user_serie
has_many :user, :through => :user_serie
end
class UserSerie < ActiveRecord::Base
belongs_to :serie
belongs_to :user
end
and
class User < ActiveRecord::Base
has_many :user_serie
has_many :serie, :through => :user_serie
end
and the select is:
#series = Serie.all :joins => :user
so the generated select is:
SELECT "series".* FROM "series"
INNER JOIN "user_series" ON "series"."id" = "user_series"."serie_id"
INNER JOIN "users"
ON 0
AND "users"
AND 'id'
AND "users"."id"
AND 0
AND "user_series"
AND 'user_id'
AND "user_series"."user_id"
AND "users"."id" = "user_series"."user_id"
What can I do to make this select works?
I've tried to make the has_many with plural, but then I have this error:
uninitialized constant Serie::UserSeries

Answer 1

You have wrong relations, should be:
class Serie < ActiveRecord::Base
has_many :user_series
has_many :users, :through => :user_series
end
class UserSerie < ActiveRecord::Base
belongs_to :serie
belongs_to :user
end
class User < ActiveRecord::Base
has_many :user_series
has_many :series, :through => :user_series
end
When you get exception with uninitialized class, then use explicit :class_name like below:
class Serie < ActiveRecord::Base
has_many :user_series, :class_name => "UserSerie"
# or "::UserSerie", i'm not 100% sure which one, rather just as I wrote
has_many :users, :through => :user_series
end