Associations and (multiple) foreign keys in rails (3.2) : how to describe them in the model, and write up migrations

Question

I have 3 models: Question, Option, Rule

Question has_many options; Option needs a foreign key for question_id

Rule table consists of 3 foreign_keys:

Answer 1

You can set a foreign key in your model like this:

class Leaf < ActiveRecord::Base
belongs_to :tree, :foreign_key => "leaf_code"
end

You do not need to specify this in a migration, rails will pull the foreign key from the model class definition.