Rails validate uniqueness of attribute according to another table

Question

I have a model User, which has_many Profile. I also have Report model, which belongs_to Profile.

How can I make sure that one user has only one report? Something like

class Report
  validate_uniqueness_of profile_id, scope: :user 
end

would be great, but of course it doesn't work. (I don't want to attach user field to Report, because it mixes up ownership chain).

You have to use custom validation. Rails does not allow validating uniqueness outside the model scope — techvineet, Aug 21 '13 at 09:41

score 1 · Accepted Answer · edited Jul 15 '16 at 06:47

1

Just to give you an idea on how to implement custom validations. Check this

class Report
    validate :unique_user

    def unique_user
        if self.exists?("profile_id = #{self.profile_id}")
          errors.add(:profile_id, "Duplicate user report")
        end
    end
end

edited Jul 15 '16 at 06:47

Matt

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answered Aug 21 '13 at 13:33

techvineet

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score 0 · Answer 2 · answered Aug 21 '13 at 10:35

If I get it right, then all the profiles of a user will have the same report, right? If that's so, it means that a profile belongs to a user, so why don't you model it like that? Eg:

class User 
  has_many :profiles
  has_one :report
end

class Profile
  belongs_to :user
  has_one :report, through: :user
end

class Report
  belongs_to :user
end

Rails validate uniqueness of attribute according to another table

2 Answers2