How to build a parent with child factory in one step in order to pass validation

问题

Projects must have at least one task created at the same time to ensure the validation passes. This is the snippet I use to validate this:

class Project < ActiveRecord::Base
  validates :tasks, :length => { :minimum => 1 }
  ...
end

The challenge I'm having is create the right factory to build a project with task upfront using FactoryGirl. I'm using:

FactoryGirl.define do

  factory :task do
    name "Get this test passing"
    project
  end

  factory :project do
    title "Complete the application"
    factory :project_with_tasks do
      ignore do
        tasks_count 5
      end

      after(:create) do |project, evaluator|
        FactoryGirl.create_list(:task, evaluator.tasks_count, project: project)
      end
    end
  end

end

Now the problem is this fails as it actually creates the project, then tries to create the associated task. The error is reported as:

Failure/Error: project = FactoryGirl.create(:project_with_tasks, tasks_count: 2)
 ActiveRecord::RecordInvalid:
   Validation failed: Projects must have at least one task

Turning it into before(:create) means the project isn't available to reference.

Any help would be greatly appreciated!

回答1:

I ended up getting it passing by building the factory in the following way:

project = FactoryGirl.build(:project)  
project.tasks << FactoryGirl.create(:task)  
project.save

This adds the task to the project before a save is done.

回答2:

Can you try on before(:create) to "build" a task for the project and after(:create) saving them in order to by pass the validation error?

ex:

  before(:build) do |instance|
    instance.tasks << build(:task, project: instance)
  end
  after(:create) do |instance|
    instance.tasks.each{|t| t.save!}
  end

来源：https://stackoverflow.com/questions/16235222/how-to-build-a-parent-with-child-factory-in-one-step-in-order-to-pass-validation