Could not find the association problem in Rails
I am fairly new to Ruby on Rails, and I clearly have an active record associat开发者_JAVA技巧ion problem, but I can't solve it on my own.
Given the three model classes with their associations:
# application_form.rb
class ApplicationForm < ActiveRecord::Base
has_many :questions, :through => :form_questions
end
# question.rb
class Question < ActiveRecord::Base
belongs_to :section
has_many :application_forms, :through => :form_questions
end
# form_question.rb
class FormQuestion < ActiveRecord::Base
belongs_to :question
belongs_to :application_form
belongs_to :question_type
has_many :answers, :through => :form_question_answers
end
But when I execute the controller to add questions to application forms, I get the error:
ActiveRecord::HasManyThroughAssociationNotFoundError in Application_forms#show
Showing app/views/application_forms/show.html.erb where line #9 raised:
Could not find the association :form_questions in model ApplicationForm
Can anyone point out what I am doing wrong?
In the ApplicationForm class, you need to specify ApplicationForms's relationship to 'form_questions'. It doesn't know about it yet. Anywhere you use the :through
, you need to tell it where to find that record first. Same problem with your other classes.
So
# application_form.rb
class ApplicationForm < ActiveRecord::Base
has_many :form_questions
has_many :questions, :through => :form_questions
end
# question.rb
class Question < ActiveRecord::Base
belongs_to :section
has_many :form_questions
has_many :application_forms, :through => :form_questions
end
# form_question.rb
class FormQuestion < ActiveRecord::Base
belongs_to :question
belongs_to :application_form
belongs_to :question_type
has_many :form_questions_answers
has_many :answers, :through => :form_question_answers
end
That is assuming that's how you have it set up.
You need to include a
has_many :form_question_answers
In your FormQuestion model. The :through expects a table that's already been declared in the model.
Same goes for your other models -- you can't supply a has_many :through
association until you've first declared the has_many
# application_form.rb
class ApplicationForm < ActiveRecord::Base
has_many :form_questions
has_many :questions, :through => :form_questions
end
# question.rb
class Question < ActiveRecord::Base
belongs_to :section
has_many :form_questions
has_many :application_forms, :through => :form_questions
end
# form_question.rb
class FormQuestion < ActiveRecord::Base
belongs_to :question
belongs_to :application_form
belongs_to :question_type
has_many :form_question_answers
has_many :answers, :through => :form_question_answers
end
It looks like your schema might be a bit wonky, but the point is you always need to add the has_many for the join table first, then add the through.
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