Two has_many links between the same models

问题

I have users which have products through a habtm link, which is working.

I want to add a link between the user model and the product model, to keep track of the creator of that product (who doesn't always own the product, of course)

But when I write in my user and product models a new link, the application screws up because I can't distinguish the creator of a product from the owner of (a lot of) products.

Can you help me ? Here is my models :

class Product < ActiveRecord::Base
  belongs_to :group
  has_and_belongs_to_many :authors
  has_and_belongs_to_many :users   # THIS IS OK (with appart table)
  has_many :users, :as => creator  # THIS LINE DOES NOT WORK AT THE MOMENT
end

class User < ActiveRecord::Base
  has_and_belongs_to_many :products
  belongs_to :user                 # THIS LINE DOES NOT WORK AT THE MOMENT
  default_scope :order => "username ASC"
end

The database is ok, and I can store the user_id under the creator column from my product, but the link product.creator.name doesn't work (because of the model is not correct, I presume), I can only read the user_id which is in the column but not get the user object with all his attributes.

rem : user.products works perfectly, but only when I remove my new link for creator...

Thanks !

回答1:

The :as syntax is for polymorphic associations - this is not what you want. Your comments about your column names are a bit ambiguous, so I'm going to assume that you have a user_id column in your products table which is the id of the creator of that product (I'm only including the relevant associations)...

class Product < ActiveRecord::Base
  has_and_belongs_to_many :users
  belongs_to :creator, :foreign_key => :user_id, :class_name => "User"
end

class User < ActiveRecord::Base
  has_and_belongs_to_many :products
  has_many :owned_products, :class_name => "Product"
end

回答2:

There is a nice gem for that: https://github.com/spovich/userstamp

I used it in my project and it works good - you just adds 'stampable' to your models and then creator_id (and updater_id) are filled authomaticly.

来源：https://stackoverflow.com/questions/6509227/two-has-many-links-between-the-same-models

标签

ruby-on-rails

relationship

has-many