Help with habtm

rubyonrails-talk
1

Hi,

I’m using habtm to create a relationship between two models:

class Question < ActiveRecord::Base

has_and_belongs_to_many :exams

end

class Exam < ActiveRecord::Base

has_and_belongs_to_many :questions

end

At some point I’m doing this:

class Exam < ActiveRecord::Base

has_and_belongs_to_many :questions

def generate

(1…5).each do

questions.create(Question::SKELETON)

end

end

end

When I do that, a sql inserts a record inside questions_exams table.

But this table has another column called: ‘order’ where I need to put some data inside

How can I populate the ‘order’ column inside join table ?

questions_exams

  • question_id

  • exam_id

- order

Thanks.

2

Don't use habtm, use has many through Exam has_many questions_exams has_many questions through questions_exams

But probably don't call it questions_exams, think of a better name

In fact even when I could use habtm I usually use has many through, I find it easier to understand. Also it is surprising how often the requirement for a little something extra in the join table pops up out of the requirements when least expected.

Colin

3

Hi Colin,

Thanks for the reply.

Even if I use has many through, how can I populate the order field dinamically ?

When I do this:

def generate

(1…5).each do

questions.create(Question::SKELETON)

end

end

Thank you.

4

Hi Colin,

Thanks for the reply.

Even if I use has many through, how can I populate the order field dinamically ? When I do this:

   def generate       (1..5).each do          questions.create(Question::SKELETON)       end    end

Possibly something like exam.questions_exams.create(order: something).create_question(...)

You can find detailed definitions of the methods that the associations provide in section 4 of

Colin