Question

I have a many-to-many association between a Post and a Category model:

categorization.rb:

class Categorization < ActiveRecord::Base
  attr_accessible :category_id, :post_id, :position

  belongs_to :post
  belongs_to :category
end

category.rb:

class Category < ActiveRecord::Base
  attr_accessible :name

  has_many :categorizations
  has_many :posts, :through => :categorizations  

  validates :name, presence: true, length: { maximum: 14 }
end

post.rb:

class Post < ActiveRecord::Base
  attr_accessible :title, :content, :category_ids

  has_many :categorizations
  has_many :categories, :through => :categorizations  

  accepts_nested_attributes_for :categorizations, allow_destroy: true

end

This works:

post_spec.rb:

describe Post do

  let(:user) { FactoryGirl.create(:user) }
  let(:category) { FactoryGirl.create(:category) }
  before { @post = user.posts.build(title: "Lorem ipsum",
                                    content: "Lorem ipsum dolor sit amet",
                                    category_ids: category) }

My problem it’s here:

factories.rb:

  factory :post do
    title "Lorem"
    content "Lorem ipsum"
    category_ids category
    user
  end

  factory :category do
    name "Lorem"
  end

reply_spec.rb:

describe Reply do

  let(:post) { FactoryGirl.create(:post) }
  let(:reply) { post.replies.build(content: "Lorem ipsum dolor sit amet") }

When I run the test for reply_spec.rb I get this error:

> undefined method `category=' for #<Post:0x9e07564>

This is part that that is not working I think:

factories.rb:

  category_ids category

Am I defining the nested attribute in a wrong way? What’s the proper one?

Answer 1

this post uses after_build hooks to create associations: Populating an association with children in factory_girl

Personally I like not having factories too complicated (makes them too specific imo), and instead instantiate any neccessary associations in the tests as needed.

factories.rb:

factory :post do
  title "Lorem"
  content "Lorem ipsum"
  user
end

factory :category do
  name "Lorem"
end

post_spec.rb:

...
let(:post) {FactoryGirl.create(:post, :category => FactoryGirl.create(:category))}

(edit — since post object has associations to categorizations and not to categories directly)

let(:post) {FactoryGirl.create(:post)}
let(:categorization) {FactoryGirl.create(:categorization, 
                                  :post=> post, 
                                  :category=> FactoryGirl.create(:category))}