Factory_girl singleton monkey patch

gistfile1.rb

# I put this as spec/support/factory_girl_singleton.rb
# this get required from spec_helper.rb
# creates a class variable for factories that should be only created once
class Factory
  @@singletons = {}  
  def self.singleton(factory_key)
    begin      
      @@singletons[factory_key] = Factory.create factory_key 
    rescue ActiveRecord::RecordInvalid, ActiveRecord::RecordNotUnique
    end
    return @@singletons[factory_key]
  end
end

# Usage example
# ---------------------------
# User belongs to school
Factory.define :user do |f|
  f.sequence(:login) { |n| Faker::Internet.user_name }
  f.school { Factory.singleton(:school) }
end

# School admin belongs to same school
Factory.define(:school_admin, :class => "User") do |f|
  f.sequence(:login) { |n| Faker::Internet.user_name }
  f.role "school_admin"
  f.school { Factory.singleton(:school) }
end

After reading this: http://stackoverflow.com/questions/9678365/factorygirl-in-rails-associations-w-unique-constraints

I changed the singleton implementation to the following, which works.

module FactoryGirl

  class Singleton
    @@singletons = {}

    def self.execute(factory_key)
      begin
        @@singletons[factory_key] = FactoryGirl.create(factory_key)
      rescue ActiveRecord::RecordInvalid, ActiveRecord::RecordNotUnique
        # already in DB so return nil
      end

      return @@singletons[factory_key]
    end
  end

end

And now you can call it like this:

FactoryGirl.define do
  factory :test, :class => Test do
    name "Test X"
    active true
  end

  factory :test_rule, :class => TestRule do
    rule { |rule| FactoryGirl::Singleton.execute(:rule_with_params) }
    test { |test| FactoryGirl::Singleton.execute(:test) }
    value "test value"
  end
end

Not sure if I understand this correctly, but the above implementation still creates new Instances when I use it like that. I had to change line 7 to the following:

    @@singletons[factory_key] ||= FactoryGirl.create(factory_key)

to stop creating new Instances if they already existed.

I do not experience the same behavior. I added a puts inside of the rescue and it shows up in ruby console on subsequent executions.

I did the same, the rescue gets never executed. The reason for this are most certainly our messed up configurations, since we just upgraded form 3.0 to 3.2. Thanks for your reply tough, I'll post the reason if I find it.

I think the reason is pretty obvious. The method proposed will only work in models that have an uniqueness validation (validates_uniqueness_of), and won't, for sure, be created twice since AR will complain about it. If the model doesn't have/need this kind of validation, the line:

@@singletons[factory_key] = FactoryGirl.create(factory_key)

Will always succeed and no exception will be raised. I did this:

module FactoryGirl
  @@singletons = {}
  def self.singleton(factory_key,factory=nil)
    @@singletons[factory_key] ||= FactoryGirl.create(factory || factory_key)
  end
end

This way, I can do this:

FactoryGirl.define do
  factory :person do
    name "Test"
    domain { FactoryGirl.singleton :domain }

    factory :another_person do
      domain { FactoryGirl.singleton :second_domain, :domain }
    end
  end

  factory :product do
    name "A product"
    domain { FactoryGirl.singleton :domain }
  end
end