Question

I have this rails model association (has_many :through)

class User < ActiveRecord::Base
  has_many :assignments
  has_many :roles, :through => :assignments  
end

class Assignment < ActiveRecord::Base
  belongs_to :user
  belongs_to :role
end

class Role < ActiveRecord::Base
  has_many :assignments
  has_many :users, :through => :assignments
end

I only have 3 roles (for now) in my application, each role :name is unique. So the role database contains 3 entries for now, user, admin, moderator.

How can I create factories so that I can create users, admins, and moderators and their roles ?

I would love to do something like:

(the role :name is checked for uniqueness, so it shouldn’t create 1 role entry per user, it should instead create 1 assignment to a role per user.)

# Create my roles
FactoryGirl.create(:role, :name => 'admin')  
FactoryGirl.create(:role, :name => 'user')
FactoryGirl.create(:role, :name => 'moderator')

# Create 10 users and 10 moderators assuming that the username is sequential or something
for i in 0..10
    user = FactoryGirl.create(:user) # user.roles.first.name.eql? 'user' #should be true
    mod = FactoryGirl.create(:moderator)  # mod.roles.first.name.eql? 'moderator' #should be true
end

How would you create the factories to model this association with FactoryGirl ?

Answer 1

I contacted Josh Clayton (maintainer of Factory Girl) about this issue, he was kind to reply the following:

The uniqueness constraint is where this will get you – sadly, you’ll have to create roles outside of the loop, name them and reuse those names. There may be other ways to hack around it, but I’m not really sure if and how you’d go about it.

So in the end I solved the issue by doing something like:

     user_role = FactoryGirl.create(:role, :title => 'user')

     for i in (1..10) do
       user = FactoryGirl.create(:user)
       user.roles << user_role 
     end

Just forgot about the “assignment” intermediate table.