Ajax Form Validation Messages don't show - asp.net-mvc

Question

This is for the first time I'm working on validations in Asp.Net MVC-4.
The problem here is that the validation messages don't show for the
required fields even when I post an empty form.
This is the form I'm using:
#using (Ajax.BeginForm("Save","DSA",
new AjaxOptions { OnSuccess = "OnSuccess", OnFailure = "OnFailure" }))
{
#Html.TextBoxFor(m => m.Insert_DSA.DSAId)
#Html.ValidationMessageFor(m => m.Insert_DSA.DSAId)
#Html.TextBoxFor(m => m.Insert_DSA.Firstname)
#Html.ValidationMessageFor(m => m.Insert_DSA.Firstname)
<input type="submit" value="Save" />
}
And in the Model Class:
[Required(ErrorMessage = "DSA ID is required")]
public string DSAId { get; set; }
[Required(ErrorMessage = "First Name is required")]
public string Firstname { get; set; }
And this is the controller:
public ActionResult Save(Models.clsDSAMaster MyModel,string submit)
{
string data = "";
if (ModelState.IsValid)
{
MyModel.Insert_DSA.addDSA(MyModel.Insert_DSA, Session["EmpCode"].ToString());
data="success";
}
else
{
data="Faliure";
}
return Content(data, "text/html");
}
Can anyone please help me get it to work and enlighten me a little on how validations work in MVC.
P.S : The model binding and the data retrieval from the model on the form submit is working perfectly.

Answer 1

You have to enable unobtrusive JavaScript. You can do it in the configuration file:
<configuration>
<appSettings>
<add key="ClientValidationEnabled" value="true"/>
<add key="UnobtrusiveJavaScriptEnabled" value="true"/>
</appSettings>
</configuration>
or you can also turn it on form the code:
HtmlHelper.ClientValidationEnabled = true;
HtmlHelper.UnobtrusiveJavaScriptEnabled = true;