ASP.NET MVC - Custom validation message for value types

Question

When I use UpdateModel or TryUpdateModel, the MVC framework is smart enough to know if you are trying to pass in a null into a value type (e.g. the user forgets to fill out

Answer 1

I've been using the awesome xVal validation framework. It lets me do all my validation in the model (Even LINQ-SQL :)). It also emits the javascript required for client side validation.

EDIT: Sorry left out the link for how to get it working for LINQ-SQL

The basic workflow goes something like this.

public partial class YourClass
{
    [Required(ErrorMessage = "Property is required.")]
    [StringLength(200)]
    public string SomeProperty{ get; set; }
}

---

try
{
    // Validate the instance of your object
    var obj = new YourClass() { SomeProperty = "" }
    var errors = DataAnnotationsValidationRunner.GetErrors(obj);
    // Do some more stuff e.g. Insert into database
}
catch (RulesException ex)
{
    // e.g. control name 'Prefix.Title'
    ex.AddModelStateErrors(ModelState, "Prefix");   
    ModelState.SetModelValue("Prefix.Title", new ValueProviderResult(ValueProvider["Prefix.Title"].AttemptedValue, collection["Prefix.Title"], System.Globalization.CultureInfo.CurrentCulture));

}