FactoryGirl: why does attributes_for omit some attributes?

factory-bot, ruby-on-rails-3

Solution

Short Answer:

By design, FactoryGirl's `attribues_for` intentionally omits things that would trigger a database transaction so tests will run fast. But you can can write a `build_attributes` method (below) to model all the attributes, if you're willing to take the time hit.

Original answer

Digging deep into the FactoryGirl documentation, e.g. this wiki page, you will find mentions that `attributes_for` ignores associations -- see update below. As a workaround, I've wrapped a helper method around `FactoryGirl.build(...).attributes` that strips `id`, `created_at`, and `updated_at`:

def build_attributes(*args)
  FactoryGirl.build(*args).attributes.delete_if do |k, v| 
    ["id", "created_at", "updated_at"].member?(k)
  end
end

So now:

>> build_attributes(:premise_group)
=> {"name"=>"PremiseGroup_21", "user_id"=>29, "is_visible"=>false, "is_open"=>false}

... which is exactly what's expected.

update

Having absorbed the comments from the creators of FactoryGirl, I understand why `attributes_for` ignores associations: referencing an association generates a call to the db which can greatly slow down tests in some cases. But if you need associations, the `build_attributes` approach shown above should work.

Problem

I want to use FactoryGirl.attributes_for in controller testing, as in: ``` it "raise error creating a new PremiseGroup for this user" do expect { post :create, {:premise_group => FactoryGirl.attributes_for(:premise_group)} }.to raise_error(CanCan::AccessDenied) end ``` ... but this doesn't work because #attributes_for omits the :user_id attribute. Here is the difference between `#create` and `#attributes_for`: ``` >> FactoryGirl.create(:premise_group) => #<PremiseGroup id: 3, name: "PremiseGroup_4", user_id: 6, is_visible: false, is_open: false) >> FactoryGirl.attributes_for(:premise_group) => {:name=>"PremiseGroup_5", :is_visible=>false, :is_open=>false} ``` Note that the :user_id is absent from `#attributes_for`. Is this the expected behavior? FWIW, my factories file includes definitions for `:premise_group` and for `:user`: ``` FactoryGirl.define do ... factory :premise_group do sequence(:name) {|n| "PremiseGroup_#{n}"} user is_visible false is_open false end factory :user do ... end end ```

Original source