ruby-on-rails – factory_girl中的has_and_belongs_to_many关联

class Company < ActiveRecord::Base
    has_and_belongs_to_many :tags
end

class Tags < ActiveRecord::Base
    has_and_belongs_to_many :companies

    validates :type,:inclusion => { :in => %w(market location) } 
end

我已经看过StackOverflow上的先前答案(包括this one),但是大多数都已经过时和/或没有正确的答案.有没有人可以用Factorygirl帮助定义这两个对象的工厂？

更新

这就是我到目前为止所提出的问题

FactoryGirl.define do
factory :tag do
    id  448
        trait :market do
        type "market"
    end
    trait :location do
        type "location"
    end
    name "software"
end

factory :company do
    id  1234
    name "Apple Inc."
    factory :company_with_tags do
        #setting the default # of tags for companies
        ignore do
            tag_count   2
        end

            after(:create) do |company,evaluator|
                FactoryGirl.create_list(:tag,evaluator.tag_count,company: company)
            end 
    end
end
end