Associations are very important when we are working with relational databases. Writing relations in models is easy but when it comes testing them, it is a painful task.
Factory girl associations makes this easy. Before going into details, lets get the basics right.
What is Factory Girl?
Factory_girl is a fixtures replacement with a straightforward definition syntax, support for multiple build strategies (saved instances, unsaved instances, attribute hashes, and stubbed objects), and support for multiple factories for the same class (user, admin_user, and so on), including factory inheritance. Read more of it here.
Testing Assocations
has_one association
Scenario : “user location” has one “email preference”
There are two ways to implement this.
- You could define relation in user location factory. First the factory creates the email preference object and then it creates user location object.
# spec/factories/user_location.rb
Factory.define :user_location , :class => UserLocation do |ul|
ul.email_preference { |ep| ep.association(:user_location) }
end
[/sourcecode]
- You could alternatively define the same association in email preference factory. First the factory creates user location object and then it creates email preference object.
[sourcecode lang=”ruby”]
# spec/factories/email_preference.rb
Factory.define :email_preference , :class => EmailPreference do |ep|
ep.association :user_location
end
[/sourcecode]
has_many association
Scenario: “City” has many “deals”
Note, the factory automatically creates the deal object and then it creates city object and associates the two.
[sourcecode lang=”ruby”]
# spec/factories/city.rb
Factory.define :city, :class => City do |c|
c.deals { |d| [d.association(:deal)] }
end
[/sourcecode]
has_many => through association
Scenario : “User” has many contests “through” ads
First the factory creates contest object and user object and then it creates ad object.
[sourcecode lang=”ruby”]
# spec/factories/ad.rb
Factory.define :ad, :class => Ad do |ad|
ad.association :contest
ad.association :user
end
[/sourcecode]
(or)
First the factory creates ‘user’ object and then it creates ‘ad’ object and then it creates ‘contest’ object.
[sourcecode lang=”ruby”]
# spec/factories/contest.rb
Factory.define :contest, :class => contest do |c|
c.ads { |ad| [ad.association(:ad)] }
end
[/sourcecode]
And in ‘ad’ factory
[sourcecode lang=”ruby”]
# spec/factories/ad.rb
Factory.define :ad, class => Ad do |ad|
ad.association :user
end
[/sourcecode]
Polymorphic relations
Among all relations defining polymorphic relations is a little bit complicated task.
Scenario : They are many type of ads like video, print, audio etc. So here video is one type of an ‘Ad’. First it creates ‘video’ object and then store resource type and ID in ‘ad’ object. Let’s see how we can define this in factories :
[sourcecode lang=”ruby”]
# spec/factories/ad.rb
Factory.define :ad, :class => Ad do |ad|
ad.association :resource, :factory => video
end
[/sourcecode]
factory_girl is awesome! nice post 😉
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Great post!
Is it possible if we want object association with custom attribute?
Let says, we have a factory :
Factory.define(:user_company) do |uc|
uc.association :user, :factory => :user
uc.association :company, :factory => :company
end
So, we can call it:
Factory(:user_company, :is_admin => true, :approved => true)
Then we will get:
eg. UserCompany :id => 1, :user_id => 1, :company_id => 1
User :id => 1, :name => “user_1”
Company :id => 1, :name => “company_1”
But I don’t want the user with name “user_1”, I want to create the user with anything name..
Yes you can do. In your case you have to do as following:
uc.association :user, :factory => :user, :attributes => {:name => “user_2”}
uc.association :company, :factory => :company, :attributes => {:name => “company_2” }
what changes required if we have Scenario: ”City” embeds_many “deals”
When it comes to embeds_many we have to build the child object, assign to parent and then save as child object can’t exist without parent.
your factory looks like
#spec/factories/city.rb
Factory.define :city, :class => City do |c|
c.after_build {|c| c.deals = [Factory.build(:deal)]}
end
FactoryBot.define do
factory :company, :class => Company do |c|
c.vendors { |v| [v.association(:vendor)] }
c.name {‘Demo Changed name’}
c.contact_first {‘Cary’}
c.contact_last {‘Pennington’}
c.phone1 {‘5555555555’}
c.phone2 {‘(222) 222-2222’}
c.email {‘carypenn+demo@gmail.com’}
c.tin {nil}
c.created_at {‘2019-03-19 04:37:59’}
c.updated_at {‘2019-06-26 17:10:03’}
c.deleted_at {nil}
c.delivery_method {‘Electronic’}
association :account, factory: :account
end
end
In this company with has_many vendors relationship facing systemstack error stack level too deep ? why?