I'm using Entity Framework code-first and so I make liberal use of Data Annotations. I use the [Key] annotation, which is from sealed class KeyAttribute and noticed that it has no client-side validation as it inherits from the Attribute class and not the ValidationAttribute class.
Because the class is sealed, I can't inherit from it. Is there another way to add validation through data annotation without simply making another attribute that mimics [Key]?
(I'm attempting to avoid something like [Key, KeyValidation("There may only be one!")])