Custom model validation of dependent properties using Data Annotations

Question

Since now I\'ve used the excellent FluentValidation library to validate my model classes. In web applications I use it in conjunction with the jquery.validate plugin to per

Answer 1

Because the methods of the DataAnnotations of .NET 3.5 don't allow you to supply the actual object validated or a validation context, you will have to do a bit of trickery to accomplish this. I must admit I'm not familiar with ASP.NET MVC, so I can't say how to do this exactly in conjunction with MCV, but you can try using a thread-static value to pass the argument itself. Here is an example with something that might work.

First create some sort of 'object scope' that allows you to pass objects around without having to pass them through the call stack:

public sealed class ContextScope : IDisposable 
{
    [ThreadStatic]
    private static object currentContext;

    public ContextScope(object context)
    {
        currentContext = context;
    }

    public static object CurrentContext
    {
        get { return context; }
    }

    public void Dispose()
    {
        currentContext = null;
    }
}

Next, create your validator to use the ContextScope:

public class CustomValidationAttribute : ValidationAttribute
{
    public override bool IsValid(object value)
    {
         Event e = (Event)ObjectContext.CurrentContext;

         // validate event here.
    }
}

And last but not least, ensure that the object is past around through the ContextScope:

Event eventToValidate = [....];
using (var scope new ContextScope(eventToValidate))
{
    DataAnnotations.Validator.Validate(eventToValidate);
}

Is this useful?