How to create an association with a value lazy-evaluated from another association

[Simone Carletti]

Hello,

Is it possible to use an association as the value for another association in a trait?

Let me describe a (simplified) example. I have 3 models

- User

- Forum (belongs_to :forum)

- Thread (belongs_to :forum, belongs_to :user)

Please note that Thread contains an user_id, it does not belong to User using Forum (at the time being, I can't change such constraint).

What I'd like to know, is if there a way to define a trait like the one

FactoryGirl.define do

  factory :thread do

    trait :with_forum do

      association :user

      # Lazy-evaluate the value of user to the previously created factory

      association :forum, user: user

    end

  end

end

What the trait is supposed to do is to create an user and associate it to the thread.

Then it should create a forum, but the user should be the same instance previously created.

There are mainly two reasons:

1. The user associated with the forum is the same of the thread
2. I don't want to create two user factories on cascade

Any idea? I tried to use the lazy evaluation, but no way to use it with associations.

Thanks,

-- Simone