How to create has_and_belongs_to_many associations in Factory girl

Question

Given the following

class User < ActiveRecord::Base
  has_and_belongs_to_many :companies
end

class Company < ActiveRecord::Base
  has_and_belongs_to_many :users
end

how do you define factories for companies and users including the bidirectional association? Here's my attempt

Factory.define :company do |f|
  f.users{ |users| [users.association :company]}
end

Factory.define :user do |f|
  f.companies{ |companies| [companies.association :user]}
end

now I try

Factory :user

Perhaps unsurprisingly this results in an infinite loop as the factories recursively use each other to define themselves.

More surprisingly I haven't found a mention of how to do this anywhere, is there a pattern for defining the necessary factories or I am doing something fundamentally wrong?

Solution 1

Factorygirl has since been updated and now includes callbacks to solve this problem. Take a look at http://robots.thoughtbot.com/post/254496652/aint-no-calla-back-girl for more info.

Solution 2

Here is the solution that works for me.

FactoryGirl.define do

  factory :company do
    #company attributes
  end

  factory :user do
   companies {[FactoryGirl.create(:company)]}
   #user attributes
  end

end

if you will need specific company you can use factory this way

company = FactoryGirl.create(:company, #{company attributes})
user = FactoryGirl.create(:user, :companies => [company])

Hope this will be helpful for somebody.

Solution 3

In my opinion, Just create two different factories like:

 Factory.define :user, :class => User do |u|
  # Just normal attributes initialization
 end

 Factory.define :company, :class => Company do |u|
  # Just normal attributes initialization
 end

When you write the test-cases for user then just write like this

 Factory(:user, :companies => [Factory(:company)])

Hope it will work.

Solution 4

I couldn´t find an example for the above mentioned case on the provided website. (Only 1:N and polymorphic assocations, but no habtm). I had a similar case and my code looks like this:

Factory.define :user do |user|
 user.name "Foo Bar"
 user.after_create { |u| Factory(:company, :users => [u]) }
end

Factory.define :company do |c|
 c.name "Acme"
end

Solution 5

What worked for me was setting the association when using the factory. Using your example:

user = Factory(:user)
company = Factory(:company)

company.users << user 
company.save! 

View more solutions

Comments

[Daniel Beardsley]

Shouldn't that be Employment belongs_to :user and Employment belongs_to :company with the join model connecting one Company with one User?

[auralbee]

My conclusion from a quick read through the post you mentioned is that it depends on your use case whether to choose habtm or has_many :through. There is no real "winner".

[Milan Novota]

Well, the only overhead when using hmt is that you have to have id defined on the through table. Right now, I can't imagine a situation when that could cause any problem. I don't say that habtm is of no use, just that in 99% use cases it makes more sense to use hmt (because of its advantages).

[dfens]

what if there is validation of non-zero user count ?

[dmonopoly]

The link doesn't actually say how to handle has_and_belongs_to_many... I don't see how to do this...

[blakkheartt12]

Thanks this is the only example I could get working. Factory girl is a big headache for habtm.

[Mik]

Thank you, most neat of all solutions.

[sbeam]

-1, just because HMT has more 'advantages' only means you should use it if you NEED those advantages. Pet peeve, because I'm working on a project now where the developer used HMT in several cases where HABTM would have sufficed. The codebase is therefore larger, more complex, less intuitive and produces slower SQL joins because of it. So, use HABTM when you can, then when you NEED to create a separate join model to store extra info about each association, only then use HMT.

[Tony Beninate]

Thank you. This has fixed my problem after hours of frustration.

[Raf]

Shouldn't it be : after_create { |company, evaluator| FactoryGirl.create_list(:user, evaluator.users_count, companies: [company]) } ?

[Raf]

This no longer works with recent versions of FactoryGirl (i'm thinking Rails 3)

[spier]

This only works for me when all the factories are in one file which is quite undesirable. Therefore the solution mentioned by @opsb below seems to be better.

[Michael Yagudaev]

Callback syntax has now been changed to: after(:create) instead of after_create in factory girl as mentioned here: stackoverflow.com/questions/15003968/…

[monteirobrena]

foos { |a| [a.association(:foo)] } helps me a lot! Thank you!