Range annotation between nothing and 100?

Question

I have a [Range] annotation that looks like this:

[Range(0, 100)]
public int AvailabilityGoal { get; set; }

My webpage looks like this:

Answer 1

I guess you could override the Range object and add this behaviour.

public class OptionalRange : RangeAttribute {
    public override bool IsValid(object value) {
        if (value == null || (int)value == 0) return true;
        return base.IsValid(value);
    }
}