asp.net mvc2 validations

I am using DataAnnotations for validation (including client side)

I have a form with multiple fields. Basic validation for individual fields work fine. Now there are a couple of fields of which atleast one needs to have a value (if there are 3 fields then either 1st or 2nd or 3rd field should have a value).

I have read 开发者_运维知识库quite a few posts on this site and couple of blog entries. But I couldn't find a solution that works in the above mentioned scenario. I might have missed something or doing it incorrectly.

Can you help with this please?

try this

[AttributeUsage(AttributeTargets.Class, AllowMultiple = true, Inherited = true)]
public sealed class EitherOr : ValidationAttribute
{
    private const string _defaultErrorMessage = "'{0}' OR '{1}' OR '{2}' must have a value";
    private readonly object _typeId = new object();

    public EitherOr(string prop1, string prop2, string prop3)
        : base(_defaultErrorMessage)
    {
        Prop1 = prop1;
        Prop2 = prop2;
        Prop3 = prop3;

    }

    public string Prop1 { get; private set; }
    public string Prop2 { get; private set; }
    public string Prop3 { get; private set; }

    public override object TypeId
    {
        get
        {
            return _typeId;
        }
    }

    public override string FormatErrorMessage(string name)
    {
        return String.Format(CultureInfo.CurrentUICulture, ErrorMessageString, Prop1, Prop2,Prop3);
    }

    public override bool IsValid(object value)
    {
        if(string.IsNullOrEmpty(Prop1)&&string.IsNullOrEmpty(Prop2) && string.IsNullOrEmpty(Prop3))
        {
            return false;
        }
        return true;
    }

then mark your class with the EitherOr attribute:

[EitherOr("Bar","Stool","Hood", ErrorMessage = "please supply one of the properties")]
    public class Foo
    {
        public string Bar{ get; set;}
        public string Stool{ get; set;}
        public string Hood{ get; set;}
    }

Please note that i made use of string properties, if your property is of other type, makle sure to change the IsValid(object value) validation