Ruby on Rails：使validates_uniqueness_of起作用

Question

I have two params :work and :grade. In the model, before saving I want to use validates_uniqueness_of to check given a unique work, there is only one grade. Grade can be the same for other work. How would I write this?

Edit:

validates_uniqueness_of :work, :scope => :grade

Answer 1

If you have a deprecated syntax warning, you can write it so:

validates :work, uniqueness: {scope: :grade}, presence: true

Edit:

It seems you need a two way checking, so perhaps adding this will work:

validates :grade, uniqueness: {scope: :work}, presence: true

Although under high load I've seen this fail, so best is to create a database constraint.