ruby - Rails has_one per scope -


i have 3 models follows:

    class user < activerecord::base       ...       has_many :feeds       ...     end      class project < acticerecord::base       ...       has_many :feeds       has_many :users, through: :feeds       ...     end      class feed < activerecord::base       ...       belongs_to :user       belongs_to :project       ...     end

i want model situation user can have maximum of 1 feed per project. know can check in custom validator within feed class, there way model using activerecord associations?

you can on feed.rb:

validates :user_id, :uniqueness => {:scope => :project_id}

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