Using factory_girl in Rails with associations that have unique constraints. Getting duplicate errors

The short answer is, "no", Factory girl doesn't have a cleaner way to do it. I seemed to verify this on the Factory girl forums.

However, I found another answer for myself. It involves another sort of workaround but makes everything much cleaner.

The idea is to change the models that represent the lookup tables to create the required entry if missing. This is OK because the code is expecting specific entries to exist. Here is an example of the modified model.

class ProductType < ActiveRecord::Base
  has_many :products

  validates_presence_of :name, :code
  validates_uniqueness_of :name, :code

  # Constants defined for the class.
  CODE_FOR_SUBSCRIPTION = "sub"
  CODE_FOR_ADDITION = "add"

  # Get the ID for of the entry that represents a trial account status.
  def self.id_for_subscription
    type = ProductType.find(:first, :conditions => ["code = ?", CODE_FOR_SUBSCRIPTION])
    # if the type wasn't found, create it.
    if type.nil?
      type = ProductType.create!(:name => 'Subscription', :code => CODE_FOR_SUBSCRIPTION)
    end
    # Return the loaded or created ID
    type.id
  end

  # Get the ID for of the entry that represents a trial account status.
  def self.id_for_addition
    type = ProductType.find(:first, :conditions => ["code = ?", CODE_FOR_ADDITION])
    # if the type wasn't found, create it.
    if type.nil?
      type = ProductType.create!(:name => 'Additions', :code => CODE_FOR_ADDITION)
    end
    # Return the loaded or created ID
    type.id
  end
end

The static class method of "id_for_addition" will load the model and ID if found, if not found it will create it.

The downside is the "id_for_addition" method may not be clear as to what it does by its name. That may need to change. The only other code impact for normal usage is an additional test to see if the model was found or not.

This means the Factory code for creating the product can be changed like this...

Factory.define :added_users_product, :parent => :product do |p|
  #p.association :product_type, :factory => :add_product_type
  p.product_type_id { ProductType.id_for_addition }
end

This means the modified Factory code can look like this...

Factory.define :cart_with_two_add_items, :parent => :cart do |o|
  o.after_build do |cart|
    cart.cart_items = [Factory(:cart_item_add_users, :cart => cart),
                       Factory(:cart_item_add_profiles, :cart => cart)]
  end
end

This is exactly what I wanted. I can now cleanly express my factory and test code.

Another benefit of this approach is the lookup table data doesn't need to be seeded or populated in migrations. It will handle itself for test databases as well as production.

These problems would be eliminated when the singletons are introduced into factories- its currently at -http://github.com/roderickvd/factory_girl/tree/singletons Issue - http://github.com/thoughtbot/factory_girl/issues#issue/16

I had a similar situation. I ended up using my seeds.rb for defining the singletons and then requiring the seeds.rb in the spec_helper.rb to create the objects into the test database. Then I can just search the appropriate object in the factories.

db/seeds.rb

RegionType.find_or_create_by_region_type('community')
RegionType.find_or_create_by_region_type('province')

spec/spec_helper.rb

require "#{Rails.root}/db/seeds.rb"

spec/factory.rb

FactoryGirl.define do
  factory :region_community, class: Region do
    sequence(:name) { |n| "Community#{n}" }
    region_type { RegionType.find_by_region_type("community") }
  end
end

I've had this same problem, and I think it's the same one referenced here: http://groups.google.com/group/factory_girl/browse_frm/thread/68947290d1819952/ef22581f4cd05aa9?tvc=1&q=associations+validates_uniqueness_of#ef22581f4cd05aa9

I think your workaround is possibly the best solution to the problem.

I think I at least found a cleaner way.

I like the idea of contacting ThoughtBot about getting a recommended "official" solution. For now, this works well.

I just combined the approach of doing it in test's code with doing it all in the factory definition.

Factory.define :cart_with_two_add_items, :parent => :cart do |o|
  o.after_build do |cart|
    prod_type = Factory(:add_product_type) # Define locally here and reuse below

    cart.cart_items = [Factory(:cart_item,
                               :cart => cart,
                               :product => Factory(:added_users_product,
                                                   :product_type => prod_type)),
                       Factory(:cart_item,
                               :cart => cart,
                               :product => Factory(:added_profiles_product,
                                                   :product_type => prod_type))]
  end
end

def test_cart_with_same_item_types
  cart = Factory(:cart_with_two_add_items)
  # ... Do asserts
end

I will update if I find a better solution.

Maybe you could try using factory_girl's sequences for product type name and code fields? For most tests I guess you won't care whether the product type's code is "code 1" or "sub", and for those where you care, you can always specify that explicitly.

Factory.sequence(:product_type_name) { |n| "ProductType#{n}" }
Factory.sequence(:product_type_code) { |n| "prod_#{n}" }        

Factory.define :product_type do |t|
  t.name { Factory.next(:product_type_name) }
  t.code { Factory.next(:product_type_code) }
end