Rails，通过与子代的属性值关联来验证has_many

Question

I have three models:

class User < ApplicationRecord
    has_many :game_accounts
    has_many :favorite_game_accounts, through: :game_account_favorites, source: :game_account
end

class GameAccount < ApplicationRecord
    belongs_to :user
    has_many :favorite_users, through: :game_account_favorites, source: :user
end

class GameAccountFavorite < ApplicationRecord
    belongs_to :user
    belongs_to :game_account

    validates_presence_of :user, :game_account
    validates_uniqueness_of :user, scope: :game_account_id
end

This means that User can have his own GameAccounts and other Users can add them to favorites.

I have added scope in order to prevent one user to have multiple favorites of the same GameAccount . However, there is one problem. User can add to favorite his own GameAccount . How to prevent user adding his own GameAccount to favorites?

Answer 1

I'm not sure that there is any built-in Rails validation for you case, so I'd suggest writing your own custom one.

In your particular case, you can verify on GameAccountFavorite instance, that game_account.user_id isn't equal to user.id .

There's plenty of ways of performing custom validation in Rails