Query thru association

Rails
1

Hi,

I’m stuck trying to figure out how to do a query to find all the
questions in a selected subject only.

My associations:

class Subject < ActiveRecord::Base
has_many :books
has_many :questions
has_many :chapters, :through => :books
has_many :sections, :through => :chapters
has_many :subsections, :through => :sections
has_many :minisections, :through => :subsections

class Question < ActiveRecord::Base
has_and_belongs_to_many :minisections

The query:
@question_list = Question.where(all the questions associated with the
subject through the above associations???)

Any suggestions where to start would be appreciated.

Thanks,
Dave

2

On 7 November 2014 03:05, Dave C. [email protected] wrote:

has_many :chapters, :through => :books
has_many :sections, :through => :chapters
has_many :subsections, :through => :sections
has_many :minisections, :through => :subsections

class Question < ActiveRecord::Base
has_and_belongs_to_many :minisections

The query:
@question_list = Question.where(all the questions associated with the
subject through the above associations???)

@question_list = @subject.questions

Note, though, that since you have subject has_many questions you also
need question belongs_to subject. Also you need to re-think your
associations as you have two routes to question from subject -
directly through the has_many but also right through the chain of
chapters, etc.

Colin

3

Colin L. wrote in post #1161913:

On 7 November 2014 03:05, Dave C. [email protected] wrote:

has_many :chapters, :through => :books
has_many :sections, :through => :chapters
has_many :subsections, :through => :sections
has_many :minisections, :through => :subsections

class Question < ActiveRecord::Base
has_and_belongs_to_many :minisections

The query:
@question_list = Question.where(all the questions associated with the
subject through the above associations???)

@question_list = @subject.questions

Note, though, that since you have subject has_many questions you also
need question belongs_to subject. Also you need to re-think your
associations as you have two routes to question from subject -
directly through the has_many but also right through the chain of
chapters, etc.

Colin

Thank you!

Dave