How to make has_many :through association with fix

问题:

I can't use factory_girl because I'm testing sunspot and need real database.

Edit: nope. It can works with sunspot. I'm wrong.

How can I build has_many :through(a.k.a many-to-many) associations in fixtures?

I google it and get a invalid solution

Edit:

Finally I use factory_girl. I google-copy-paste a snippet:

factory :tagging do 
    question { |a| a.association(:question) } 
    tag { |a| a.association(:tag) } 
end

(question has_many tags through taggings, vice versa)

It works well. But what's it? The factory_girl's readme didn't meantion this syntax. Could someone explain?

回答1:

You can find the official documentation for factory_girl, which is very complete, here.

Here is a nice (shorter) blogpost explaining factory_girl 2 (comparing it with factory-girl 1).

UPDATED:

To Explain the code a bit:

 factory :tagging do
   association :tag
 end

will look for a factory called :tag and will construct that object, and then link that to the association tag (e.g. a belongs_to) that is there inside your object :tagging.

Please note: this is the default factory. If you want taggings to share a tag, you will need to do something like

@tag = Factory(:tag)
@tagging_1 = Factory(:tagging, :tag => @tag)
@tagging_2 = Factory(:tagging, :tag => @tag)

Hope this helps.

回答2:

If it's a classic has_and_belongs_to_many association, without other information in the association model, I think the conventions allow you to write your fixtures like that :

#users.yml
john:
  first_name: John
  last_name: Doe
  hobbies: [swim, play_tennis]

#hobbies.yml
swim:
  name: Swim

play_tennis:
  name: Play Tennis

But I'm not completely sure !

回答3:

I used fixtures on testing for has_many :through by hash merge

# posts.yml
one:
  title: "Railscasts"
  url: "http://railscasts.com/"
  description: "Ruby on Rails screencasts"

# categories.yml
one:
  name: "magazine"
two:
  name: "tutorial"
three:
  name: "news"
four:
  name: "Ruby"

# posts_controller_test.rb
def test_post_create
  assert_difference 'Post.count' do
    post :create, post: posts(:one).attributes
     .merge(categories: [categories(:two), categories(:four)])
  end
end

when after adding another fixture file, and tried this it didn't work

# post_categories.yml
one:
  post: one
  category: two
two:
  post: one
  category: four

def test_post_create
  assert_difference 'Post.count' do
    post :create, post: posts(:one)
  end
end

puts posts(:one).attributes
# {"id"=>980190962, "url"=>"http://railscasts.com/", "title"=>"Railscasts", "description"=>"Ruby on Rails screencasts", "created_at"=>Thu, 14 May 2015 18:27:20 UTC +00:00, "updated_at"=>Thu, 14 May 2015 18:27:20 UTC +00:00}

puts posts(:one).attributes
      .merge(categories: [categories(:two), categories(:four)])
# {"id"=>980190962, "url"=>"http://railscasts.com/", "title"=>"Railscasts", "description"=>"Ruby on Rails screencasts", "created_at"=>Thu, 14 May 2015 18:30:23 UTC +00:00, "updated_at"=>Thu, 14 May 2015 18:30:23 UTC +00:00, "category_ids"=>[980190962, 1018350795]}