title: FactoryGirl before(:create) callback not creating associations
body: <p>I have a FactoryGirl factory, that creates a <code>Order</code> but the before(:create) callback does not create the associated factory object:</p>
  
  <p><strong>Parent Class</strong></p>
  
  <pre><code>class Order &lt; ActiveRecord::Base
    attr_accessible :tax, :total
    has_many :order_lines
  
    validates :user, presence: true
    validates :order_lines , presence: true
  end
  </code></pre>
  
  <p><strong>Child Class</strong></p>
  
  <pre><code>class OrderLine &lt; ActiveRecord::Base
    attr_accessible :order, :product, :qty
    belongs_to :order
    belongs_to :product
    ...
    ...
    validates :order, presence: true
  end
  </code></pre>
  
  <p><strong>Factory</strong></p>
  
  <pre><code>Factory :order do
    ...
    ignore do
      number_or_order_lines 1
    end
    before(:create) do |order, evaluator|
      FactoryGirl.create_list :order_line, evaluator.number_or_order_lines, order: order
    end
  end
  
  Factory :order_line do
     association :user
     association :order
     ...
  end
  </code></pre>
  
  <p><strong>PROBLEM</strong></p>
  
  <p>In my rspec test, if I create a order object:</p>
  
  <pre><code>describe Order do
    before {@order = FactoryGirl.create(:order) }  =&gt; #throws error (see below)
  end
  </code></pre>
  
  <p><strong>ERROR</strong>
  ActiveRecord::RecordInvalid
  Validation failed Order Lines can't be blank</p>
  
  <p><strong>UPDATE</strong></p>
  
  <p>I can however successfully do the following but obviously only accomplishes creating one:</p>
  
  <pre><code>after(:build) do |order, evaluator|
    order.order_lines &lt;&lt; FactoryGirl.build(:order_line, order: order)
  end
  </code></pre>
  
  <p><strong>Hypothesis</strong> -  I can see where the <code>create_list</code> might be attempting to save the <code>OrderLine</code> which would cause an error since the parent hasn't been saved - but I don't know if it still returns a OrderLine object that is just in an invalid state and therefore the order_lines collection on the order object should still not be empty.</p>