Stay on same page if form is not valid - asp.net-mvc

Question

public ActionResult Add(Models.ContactModel contact)
{
if (ModelState.IsValid)
{
DAL.Contact mappedContact = Mapper.Map<Models.ContactModel, DAL.Contact>(contact);
repository.AddContact(mappedContact);
return RedirectToAction("Index");
}
else
/* What to return here */
}
This is the controller for adding contact to the database. I am validating the form using data annotations if the form is valid i am redirecting it to the index page. If it is not valid it should stay on the same page showing error message. what to write in else part. can any one suggest me.There is no view for Add Controller.
<div>
<label>Name</label>
#Html.ValidationMessageFor(model => model.Name, null, new { #class = "error-message"})
#Html.TextBoxFor(model => model.Name, new { #class = "long-box" })
</div>
<div>
<label>Email</label>
#Html.ValidationMessageFor(model => model.Email, null, new { #class = "error-message" })
#Html.TextBoxFor(model => model.Email, new { #class = "long-box" })
</div>
<div class="mob-land-container">
<label>Mobile</label>
#Html.ValidationMessageFor(model => model.MobileNumber, null, new { #class = "error-message" }) <br>
#Html.TextBoxFor(model => model.MobileNumber, new { #class = "short-box" })
</div>
<div class="mob-land-container" id="landline-container">
<label>Landline</label>
#Html.ValidationMessageFor(model => model.LandlineNumber, null, new { #class = "error-message" })<br>
#Html.TextBoxFor(model => model.LandlineNumber, new { #class = "short-box" })
</div>
<div>
<label>Website</label>
#Html.ValidationMessageFor(model => model.Website, null, new { #class = "error-message" })
#Html.TextBoxFor(model => model.Website, new { #class = "long-box" })
</div>
<div>
<label>Address</label>
#Html.ValidationMessageFor(model => model.Address, null, new { #class = "error-message" })
#Html.TextAreaFor(model => model.Address, new { #class = "address-box" })
</div>
</div>
<div class="button-container">
<input type="button" id="cancel" value="Cancel" onclick="location.href='#Url.Action("Index", "Contact")'" />
<input type="submit" id="add" value="Add" onclick="location.href='#Url.Action("Add", "Contact")'" />
</div>
This is the form where i am getting data to controller.
public class ContactModel
{
public int Id { get; set; }
[Required(ErrorMessage = "Name is required")]
public string Name { get; set; }
[Required(ErrorMessage = "Email is required")]
public string Email { get; set; }
[Required(ErrorMessage = "Mobile Number is required")]
public string MobileNumber { get; set; }
[Required(ErrorMessage = "Landline Number is required")]
public string LandlineNumber { get; set; }
[Required(ErrorMessage = "Website is required")]
public string Website { get; set; }
[Required(ErrorMessage = "Address is required")]
public string Address { get; set; }
}
This is the model class.
Thanks in advance.

Answer 1

I like to flip the login in situations like this. If the model isn't valid just return it back to the view. the model binder on the POST will take care of the validations and once you send the model back to the view, you will see the individual validations on the screen.
If you have any dropdown, you will need to re-populate them before sending sending the model back.
public ContactController : Controller
{
[HttpGet]
public ActionResult Add()
{
return View(new Models.ContactModel());
}
[HttpPost]
public ActionResult Add(Models.ContactModel contact)
{
if (!ModelState.IsValid)
{
return View(contact);
}
DAL.Contact mappedContact = Mapper.Map<Models.ContactModel, DAL.Contact>(contact);
repository.AddContact(mappedContact);
return RedirectToAction("Index");
}
}
The GET action returns the empty form.
The POST action posts the model to the server.
Your view model should be named Add.cshtml to that mvc can automatically pick it up.
And change your view buttons
<div class="button-container">
#Html.ActionLink("Cancel", "Index", "Contact")
<input type="submit" value="Save" />
</div>
Style the Cancel link to look like a button
Your submit will automatically submit to the Add POST method.
The model state check returns the model back to the view with the validation information in it so that you can correct the form.