FactoryGirl关联模型故障：“SystemStackError：堆栈级别太深”

Question

I am using Ruby on Rails 3.0.9, RSpec-rails 2 and FactoryGirl. I am trying to state a Factory association model but I am in trouble.

I have a factories/user.rb file like the following:

FactoryGirl.define do
  factory :user, :class => User do
    attribute_1
    attribute_2
    ...

    association :account, :factory => :users_account, :method => :build, :email => 'foo@bar.com'
  end
end

and a factories/users/account.rb file like the following:

FactoryGirl.define do
  factory :users_account, :class => Users::Account do
    sequence(:email) {|n| "foo#{n}@bar.com" }
    ...
  end
end

The above example works as expected in my spec files, but if in the factory :users_account statement I add the association :user code so to have

FactoryGirl.define do
  factory :users_account, :class => Users::Account do
    sequence(:email) {|n| "foo#{n}@bar.com" }
    ...
    association      :user
  end
end

I get the following error:

Failure/Error: Unable to find matching line from backtrace
SystemStackError:
  stack level too deep

How can I solve that problem so to access associated models from both sides\\factories (that is, in my spec files I would like to use RoR association model methods like user.account and account.user ) ?

PS: I read the Factory Girl and has_one question and my case is very close to the case explained in the linked question. That is, I have an has_one association too (between User and Users::Account classes).

Answer 1

According to the docs , you can't just put both sides of the associations into the factories. You'll need to use their after callback to set an object(s) to return.

For instance, in the factories/users/account.rb file, you put something like

after(:build) do |user_account, evaluator|
    user_account.user = FactoryGirl.build(:user, :account=>user_account)
end

For has_many associations, you'll need to use their *_list functions.

after(:build) do |user_account, evaluator|
    user_account.users = FactoryGirl.build_list(:user, 5, :account=>user_account)
end

---

Note: I believe the example in the docs is a bit misleading it doesn't assign anything to the object. I believe it should be something like (note the assignment).

# the after(:create) yields two values; the user instance itself and the
# evaluator, which stores all values from the factory, including ignored
# attributes; `create_list`'s second argument is the number of records
# to create and we make sure the user is associated properly to the post
after(:create) do |user, evaluator|
  user.posts = FactoryGirl.create_list(:post, evaluator.posts_count, user: user)
end

Answer 2

Spyle's excellent answer (still working with Rails 5.2 and RSpec 3.8) will work for most associations. I had a use case where a factory needed to use 2 different factories (or different traits) for a single has_many association (ie. for a scope type method).

What I ended up coming up with was:

# To build user with posts of category == 'Special' and category == 'Regular'
after(:create) do |user, evaluator|
  array = []
  array.push(FactoryBot.create_list(:post, 1, category: 'Regular')
  array.push(FactoryBot.create_list(:post, 1, category: 'Special')
  user.posts = array.flatten
end

This allowed the user to have 1 post of category 'Regular' and 1 post of category 'Special.'