ASP.Net MvC framework, Html.ValidationMessage tag

Question

In this code in an Edit view, the correct vendor name text appears but it is not validated when I blank its textbox and push Save. The Vendor is a property of the Order model, and VendorName is a property in the Vendor model. They relate referentially. My form does not all input into a single table, but on satellite tables as well.

<%= Html.TextBox("Vendor.VendorName")%> <%= Html.ValidationMessage("Vendor.VendorName")%> 

Why is validation not occuring?

This seems to work, but it seems like a hack to me:

using M = HelloUranus.Models //... namespace HelloUranus.Controllers { public class OrderDetailController : Controller { //... private M.DBProxy db = new M.DBProxy(); [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, FormCollection collection) { //... var orderDetail = db.GetOrderDetail(id); //... try { if (string.IsNullOrEmpty(Request.Form["Vendor.VendorName"])) { throw new Exception(); } UpdateModel(orderDetail); db.Save(); return RedirectToAction("Details", new {id = orderDetail.odID } ); } catch { ModelState.AddRuleViolations(orderDetail.GetRuleViolations()); return View(orderDetail); } //... } //... } 

Answer 1

Did you write any validation code? You have to manually validate it in your controller. If you:

ModelState.IsValid = false; 

in the controller, for example, you will see some validation. That will trigger the ValidationSummary on the View to be shown. To actually add a validation to a single form element, use:

ModelState.AddModelError("Vendor.VendorName", string.Format("Vendor name must be at least {0} characters.",10)); 

Note that this will also set the ModelState to an invalid state and thus trigger the ValidationSummary as well.