Validating DataAnnotations with Validator class

Question

I'm trying to validate a class decorated with data annotation with the Validator class.

It works fine when the attributes are applied to the same class. But when I try to use a metadata class it doesn't work. Is there anything I should do with the Validator so it uses the metadata class? Here's some code..

this works:

public class Persona
{
    [Required(AllowEmptyStrings = false, ErrorMessage = "El nombre es obligatorio")]
    public string Nombre { get; set; }

    [Range(0, int.MaxValue, ErrorMessage="La edad no puede ser negativa")]
    public int Edad { get; set; }
}

this doesnt work:

[MetadataType(typeof(Persona_Validation))]
public class Persona
{
    public string Nombre { get; set; }
    public int Edad { get; set; }
}

public class Persona_Validation
{
    [Required(AllowEmptyStrings = false, ErrorMessage = "El nombre es obligatorio")]
    public string Nombre { get; set; }

    [Range(0, int.MaxValue, ErrorMessage = "La edad no puede ser negativa")]
    public int Edad { get; set; }
}

this is how I validate the instances:

ValidationContext context = new ValidationContext(p, null, null);
List<ValidationResult> results = new List<ValidationResult>();

bool valid = Validator.TryValidateObject(p, context, results, true);

thanks.

Answer 1

I found the answer here: http://forums.silverlight.net/forums/p/149264/377212.aspx

MVC recognizes the MetaDataType attribute, but other projects do not. Before validating, you need to manually register the metadata class:

TypeDescriptor.AddProviderTransparent(
            new AssociatedMetadataTypeTypeDescriptionProvider(typeof(Persona), typeof(Persona_Validation)), typeof(Persona));

ValidationContext context = new ValidationContext(p, null, null);
List<ValidationResult> results = new List<ValidationResult>();

bool valid = Validator.TryValidateObject(p, context, results, true);

Answer 2

Try to move the metadata class into the same namespace as the Persona class if it isn't already. I was having similar problems and moving my metadata class into the same namespace as the L2S model class worked for me.