Rails在外键上具有唯一性的唯一性，作用域的日期为created_at列的日期

Question

rails uniqueness of on foreign key with scope on date of created_at column

validates :test_id, :uniqueness => { :scope => Date(:created_at)} 

The above code wont work. But, I need similar thing to validate uniqueness on foreign key with Date(:created_at) .

Answer 1

You will need to write a custom validation, there's no way to do this with the built-in uniqueness validator.

This one works both with creating new entries, and saving existing ones (by using an existing created_at if it's there, otherwise we fall back to Date.current which is the timezone-aware way of getting "today":

validate :check_test_id

def check_test_id
  date = ( created_at || Date.current ).to_date
  if self.class.exists? ["DATE(created_at) = DATE(?) AND test_id = ?", date, test_id]
    errors.add :test_id, "is not unique for #{date}"
  end
end