Rails —如何构建belongs_to / has_many关联？

Question

Pretty simple question, I think: so I have a User model, a Product model, and a Comment model. I want the Users to be able to comment on specific products (like leave reviews for the products).

Is this the correct structure?

User
  has_many :comments

Product
  has_many :comments

Comment
  belongs_to :user
  belongs_to :product

Thanks.

Answer 1

yes it's correct if you want just comment on products, if you will comment on other model other than product, then use polymorphic association.

also don't forget to add dependent: :destroy to destroy related comments if the product is destroyed or the user is destroyed

in Product and User model add dependent: :destroy

has_many :comments, dependent: :destroy

if you want other behavior than this, there is other options, from Doc :

:dependent

Controls what happens to the associated objects when their owner is destroyed:

 :destroy causes all the associated objects to also be destroyed :delete_all causes all the associated objects to be deleted directly from the database (so callbacks will not execute) :nullify causes the foreign keys to be set to NULL. Callbacks are not executed. :restrict_with_exception causes an exception to be raised if there are any associated records :restrict_with_error causes an error to be added to the owner if there are any associated object