.net - MetadataType problem

Question

I'm using VS2008 SP1, WCF Ria Service July 2009 CTP. I found out that MetadataType does not work in partial class mode, really don't know what I have missed out:

Work:-

public partial class Person
{
    private string _Name;

    [Required(AllowEmptyStrings=false, ErrorMessage="Name required entry")]
    [StringLength(3)]
    public string Name
    {
        set{_Name = value;}
        get{return _Name;}
    }
}

class Program
{
    static void Main(string[] args)
    {
        Person p = new Person { Name="123432" };
        List res = new List();
        Validator.TryValidateObject(p,new ValidationContext(p,null,null),
            res,true);
        if (res.Count > 0)
        {
            Console.WriteLine(res[0].ErrorMessage);
            Console.ReadLine();
        }
    }
}

Not Work

public partial class Person
{
    private string _Name;

    public string Name
    {
        set{_Name = value;}
        get{return _Name;}
    }
}

[MetadataType(typeof(PersonMetadata))]
public partial class Person
{
}


public partial class PersonMetadata
{
    [Required(AllowEmptyStrings=false, ErrorMessage="Name required entry")]
    [StringLength(3)]
    public string Name;
}

class Program
{
    static void Main(string[] args)
    {
        Person p = new Person { Name="123432" };
        List res = new List();
        Validator.TryValidateObject(p,new ValidationContext(p,null,null),
            res,true);
        if (res.Count > 0)
        {
            Console.WriteLine(res[0].ErrorMessage);
            Console.ReadLine();
        }
    }
}

Answer 1

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

Before validating, you need to manually register the metadata class:

TypeDescriptor.AddProviderTransparent(
            new AssociatedMetadataTypeTypeDescriptionProvider(typeof(Person), typeof(PersonMetadata)), typeof(Person));

        List<ValidationResult> res = new List<ValidationResult>();
        bool valid = Validator.TryValidateObject(p, new ValidationContext(p, null, null), res, true);

(Original answer follows)

The problem isn't specifically with your partial class, it's that Validator.TryValidateObject doesn't seem to recognize the MetaDataType attribute. I have the same problem - the built-in validation in MVC 2 recognizes the metadata class, but TryValidateObject doesn't.

See these: Validating DataAnnotations with Validator class Validation does not work when I use Validator.TryValidateObject

As a side note, I don't know if it's necessary, but all examples I've seen for metadata classes employ the default get/set on each property:

[Required(AllowEmptyStrings=false, ErrorMessage="Name required entry")]
[StringLength(3)]
public string Name { get; set; }