how to modify json result before sending back to client - json

Question

My controller returns a JsonResult like that:
return Json(model);
How can I modify the json data on the fly before it is sent back to the client. I'd like to add validation attributes to my model so I end up with something like:
{"Label": "Test",
"ValidationRules":[{"data-val-required":"This field is required.", "data-val-length-max":25, "data-val-length":"Max 25 chars." }]}
UPDATE
public class Product
{
[Required]
String Label {get; set;}
}
when calling Json(model) with model being an instance of Product, I'd like to modify the json string before it is returned, so that it includes validation attributes.

Answer 1

Why not create a base class called ValidatableBase that has a ValidationRules property:
public class Product : ValidatableBase
{
public string Label { get; set; }
}
public abstract class ValidatableBase
{
public ValidatableBase()
{
this.ValidationRules = new Dictionary<string, string>();
}
public Dictionary<string, string> ValidationRules { get; set; }
}
public ActionResult GetProduct()
{
var product = new Product();
product.Label = "foo";
product.ValidationRules.Add("data-val-required", "this field is required");
return Json(product);
}
Inherit from this class and serialize.
Or if you're using DataAnnotations why not use the default jQuery validation and HtmlHelper methods provided by ASP.NET MVC?