How to set up factory in FactoryBot with has_many association

Question

Can someone tell me if I'm just going about the setup the wrong way?

I have the following models that have has_many.through associations:

class Listing < ActiveRecord::Base
  attr_accessible ... 

  has_many :listing_features
  has_many :features, :through => :listing_features

  validates_presence_of ...
  ...  
end


class Feature < ActiveRecord::Base
  attr_accessible ...

  validates_presence_of ...
  validates_uniqueness_of ...

  has_many :listing_features
  has_many :listings, :through => :listing_features
end


class ListingFeature < ActiveRecord::Base
  attr_accessible :feature_id, :listing_id

  belongs_to :feature  
  belongs_to :listing
end

I'm using Rails 3.1.rc4, FactoryGirl 2.0.2, factory_girl_rails 1.1.0, and rspec. Here is my basic rspec rspec sanity check for the :listing factory:

it "creates a valid listing from factory" do
  Factory(:listing).should be_valid
end

Here is Factory(:listing)

FactoryGirl.define do
  factory :listing do
    headline    'headline'
    home_desc   'this is the home description'
    association :user, :factory => :user
    association :layout, :factory => :layout
    association :features, :factory => :feature
  end
end

The :listing_feature and :feature factories are similarly setup.
If the association :features line is commented out, then all my tests pass.
When it is

association :features, :factory => :feature

the error message is undefined method 'each' for #<Feature> which I thought made sense to me because because listing.features returns an array. So I changed it to

association :features, [:factory => :feature]

and the error I get now is ArgumentError: Not registered: features Is it just not sensible to be generating factory objects this way, or what am I missing? Thanks very much for any and all input!

Hatband

Answer 1

Creating these kinds of associations requires using FactoryGirl's callbacks.

A perfect set of examples can be found here.

https://thoughtbot.com/blog/aint-no-calla-back-girl

To bring it home to your example.

Factory.define :listing_with_features, :parent => :listing do |listing|
  listing.after_create { |l| Factory(:feature, :listing => l)  }
  #or some for loop to generate X features
end

Wispy

did you end up using association :features, [:factory => :feature]? – Module

Answer 2

Alternatively, you can use a block and skip the association keyword. This makes it possible to build objects without saving to the database (otherwise, a has_many association will save your records to the db, even if you use the build function instead of create).

FactoryGirl.define do
  factory :listing_with_features, :parent => :listing do |listing|
    features { build_list :feature, 3 }
  end
end

Womanizer

This is the cat's meow. The ability to both build and create makes it the most versatile pattern. Then use this custom FG build strategy gist.github.com/Bartuz/74ee5834a36803d712b7 to post nested_attributes_for when testing controller actions that accepts_nested_attributes_for – Gatewood

upvoted, far more readable and versatile than the accepted answer IMO – Heinie

As of FactoryBot 5, the association keyword uses the same build strategy for parent and child. So, it can build objects w/o saving to the database. – Belligerent

Answer 3

You could use trait:

FactoryGirl.define do
  factory :listing do
    ...

    trait :with_features do
      features { build_list :feature, 3 }
    end
  end
end

With callback, if you need DB creation:

...

trait :with_features do
  after(:create) do |listing|
    create_list(:feature, 3, listing: listing)
  end
end

Use in your specs like this:

let(:listing) { create(:listing, :with_features) }

This will remove duplication in your factories and be more reusable.

https://robots.thoughtbot.com/remove-duplication-with-factorygirls-traits

Nucleolus

Answer 4

I tried a few different approaches and this is the one that worked most reliably for me (adapted to your case)

FactoryGirl.define do
  factory :user do
    # some details
  end

  factory :layout do
    # some details
  end

  factory :feature do
    # some details
  end

  factory :listing do
    headline    'headline'
    home_desc   'this is the home description'
    association :user, factory: :user
    association :layout, factory: :layout
    after(:create) do |liztng|
      FactoryGirl.create_list(:feature, 1, listing: liztng)
    end
  end
end

Crosscrosslet

Answer 5

Since FactoryBot v5, associations preserve build strategy. Associations are the best way to solve this and the docs have good examples for it:

FactoryBot.define do
  factory :post do
    title { "Through the Looking Glass" }
    user
  end

  factory :user do
    name { "Taylor Kim" }

    factory :user_with_posts do
      posts { [association(:post)] }
    end
  end
end

Or with control over the count:

    transient do
      posts_count { 5 }
    end

    posts do
      Array.new(posts_count) { association(:post) }
    end

Floodgate

As suggested by @sequielo below, I needed to use [association(:post, user: instance)] to avoid creating an additional post. – Lucey

Answer 6

Similar to @thisismydesign, however it created an additional post on my end (FactoryBot v6.2).

To avoid this situation, I've added keyword instance as below:

FactoryBot.define do
  factory :post do
    title { "Through the Looking Glass" }
    user
  end

  factory :user do
    name { "Taylor Kim" }

    factory :user_with_posts do
      posts { [association(:post, user: instance)] }
    end
  end
end

Polyphone

This solved it for me too. But what is "instance" and why is it needed? – Lucey

Answer 7

Here is how I set mine up:

# Model 1 PreferenceSet
class PreferenceSet < ActiveRecord::Base
  belongs_to :user
  has_many :preferences, dependent: :destroy
end

#Model 2 Preference

class Preference < ActiveRecord::Base    
  belongs_to :preference_set
end



# factories/preference_set.rb

FactoryGirl.define do
  factory :preference_set do
    user factory: :user
    filter_name "market, filter_structure"

    factory :preference_set_with_preferences do
      after(:create) do |preference|
        create(:preference, preference_set: preference)
        create(:filter_structure_preference, preference_set: preference)
      end
    end
  end

end

# factories/preference.rb

FactoryGirl.define do
  factory :preference do |p|
    filter_name "market"
    filter_value "12"
  end

  factory :filter_structure_preference, parent: :preference do
    filter_name "structure"
    filter_value "7"
  end
end

And then in your tests you can do:

@preference_set = FactoryGirl.create(:preference_set_with_preferences)

Hope that helps.

Concha