MVC Validation Not Working In Web Forms Project - asp.net-mvc

Question

I have the following code in my aspx view page:
<% using (Html.BeginForm())
{
%>
<div>
CustomerCode:
<%= Html.TextBoxFor(x=> x.CustomerCode) %>
<%= Html.ValidationMessageFor(x => x.CustomerCode)%>
and this code in my model:
public class MyModel
{
[Required(ErrorMessage="customer code req")]
[StringLength(2,ErrorMessage="must be 2 u idiot")]
public string CustomerCode {get; set;}
Though if I enter more than 2 charachters in the textbox and submit the page, in the controller when I do:
if (ModelState.IsValid)
It always says its valid? What am I missing? I have put this MVC project inside a Web Forms project but the MVC project works fine, its just the validation which is not working, any ideas? Thanks.

Answer 1

Make sure that the controller action accepts the model as parameter:
public ActionResult SomeAction(MyModel model)
{
if (ModelState.IsValid)
{
}
return View();
}
Now if you invoke:
http://example.com/myapp/home/someaction?customercode=123
The model should not be valid.

Answer 2

Hmm, it works for me on a test page with the following
public ActionResult Test()
{
MyModel model = new MyModel();
return View(model);
}
[HttpPost]
public ActionResult Test(MyModel model)
{
if (ModelState.IsValid) { }
return View(model);
}
<% using (Html.BeginForm()) {%>
<%: Html.ValidationSummary(true) %>
<fieldset>
<legend>Fields</legend>
<div class="editor-label">
<%: Html.LabelFor(model => model.CustomerCode) %>
</div>
<div class="editor-field">
<%: Html.TextBoxFor(model => model.CustomerCode) %>
<%: Html.ValidationMessageFor(model => model.CustomerCode) %>
</div>
<p>
<input type="submit" value="Create" />
</p>
</fieldset>
<% } %>
public class MyModel
{
[Required(ErrorMessage = "customer code req")]
[StringLength(2, ErrorMessage = "must be 2 u idiot")]
public string CustomerCode { get; set; }
}