Data Validation Using Annotations for jQuery AJAX Calls in MVC Applications

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using DataAnnotationAjax.Models;
using DataAnnotationAjax.Controllers.ControllerBase;

namespace DataAnnotationAjax.Controllers
{
    public class HomeController : BaseController
    {
        [HttpGet]
        public ActionResult Index()
        {
            return View(StudentRepository.GetStudent());
        }

        [HttpPost]
        public ActionResult AddStudent()
        {
            var student = new Student();

            // The TryUpdateModel will use data annotation to validate
            // the data passed over from the client. If any validation
            // fails, the error will be written to the "ModelState".
            var valid = TryUpdateModel(student);

            string studentPartialViewHtml = null;
            if (valid)
            {
                // Add the student to the repository.
                // In any pratical application, exception handling should be used
                // when making data access. In this small example, I will just cross
                // my finger to say "there is no chance to encounter exeption" when
                // adding the student. Indeed, the chance of exception is very minimal
                // when adding students to my small repositoty. If the validation is
                // successful, I will simply tell the client that the student is added.
                StudentRepository.AddStudent(student);

                // Obtain the html string from the partial view "Students.ascx"
                var students = StudentRepository.GetStudent();
                studentPartialViewHtml = RenderPartialViewToString("Students", students);
            }

            return Json(new {Valid = valid,
                             Errors = GetErrorsFromModelState(), 
                StudentsPartial = studentPartialViewHtml
            });
        }
    }
}