Dynamic Range Validation in ASP.NET MVC 2

Question

I am using ASP.NET MVC2 and trying to validate my view models using the attributes in System.ComponentModel.DataAnnotations namespace.

How can I dynamically set the permitted valid range of a RangeAttribute? For example, if I want to validate that a date entered is within an expected range.

This doesn't compile:

[Range(typeof(DateTime), 
        DateTime.Today.ToShortDateString(), 
        DateTime.Today.AddYears(1).ToShortDateString())]
    public DateTime DeliveryDate { get; set; }

because "an attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type".

Do I need to resort to creating my own custom validator?

Answer 1

You need to create your own attribute or use a none attribute based validation framework. As the message say, all parameters to any attribute needs to be constant values.

Answer 2

OK, found the answer. .NET Framework 4 provides a new CustomValidationAttribute which makes the following possible:

[Required]
[DisplayName("Ideal Delivery Date")]
[CustomValidation(typeof(HeaderViewModel), "ValidateDeliveryDate")]
public DateTime DeliveryDate { get; set; }

public static ValidationResult ValidateDeliveryDate(DateTime deliveryDateToValidate)
{
    if (deliveryDateToValidate.Date < DateTime.Today)
    {
    return new ValidationResult("Delivery Date cannot be in the past.");
    }

    if (deliveryDateToValidate.Date > DateTime.Today.AddYears(1))
    {
    return new ValidationResult("Delivery Date must be within the next year.");
    }

    return ValidationResult.Success;
}

http://msdn.microsoft.com/en-us/library/system.componentmodel.dataannotations.customvalidationattribute%28VS.100%29.aspx