Is it possible to express a check constraint?

Question

I\'m doing code-first development with Entity Framework 4.3 and it doesn\'t seem like it\'s possible to express a CHECK constraint via attribute annotations or, well, any ot

Answer 1

I've been wanting to put Check constraints in, and while there are a couple of ways to do it like the answer given here by M.Babcock and using the ExecuteSql in the Initializer to add constraints to the database manually.

But I think the easiest method is to use a RegularExpression annotation, so in your example you'd go:

public class Person
{
    [Required]
    [RegularExpression(@"Bob|Harry")]  
    public string FirstName { get; set; }

    [Required, RegularExpression(@"5|30|50")]  
    public int Age { get; set; }
}

Answer 2

You could write one yourself (untested):

public class CheckAttribute : System.ComponentModel.DataAnnotations.ValidationAttribute
{
    object[] ValidValues;

    public CheckAttribute<T>(params T[] validValues)
    {
        ValidValues = validValues;
    }

    public override bool IsValid(object value)
    {
        return ValidValues.FirstOrDefault(v => v.Equals(value)) != null;
    }
}