How to do validation from a viewmodel - asp.net-mvc-4

Question

I have a model with some validations below
public class RequestABook
{
[Required(ErrorMessage = "Name Required")]
[DisplayName("Book Name")]
public string BookName { get; set; }
[Required(ErrorMessage = "Zipcode Required")]
[DisplayName("Zipcode")]
public string ZipCode { get; set; }
[Required(ErrorMessage = "Contact Name Required")]
[DisplayName("Contact Name")]
public string ContactName { get; set; }
[Required(ErrorMessage = "Email Id Required")]
[DataType(DataType.EmailAddress)]
public string Email { get; set; }
[Required(ErrorMessage = "Book Description Required")]
public string BookDescription { get; set; }
[Required(ErrorMessage = "You need to check one answer")]
public string Answer { get; set; }
}
I have a view model here
public class RequestViewModel
{
public RequestABook MyTestViewModel { get; set; }
}
I have my main page here that loads
#model BookRequestValidation.Models.RequestViewModel
#{
ViewBag.Title = "RequestABook";
}
<h2>RequestABook</h2>
#using (Html.BeginForm())
{
#Html.ValidationSummary(true)
<fieldset>
<legend>Request Book</legend>
<div class="editor-label">
#Html.LabelFor(m => m.MyTestViewModel.BookName)
</div>
<div class="editor-field">
#Html.EditorFor(m => m.MyTestViewModel.BookName)
#Html.ValidationMessageFor(m => m.MyTestViewModel.BookName)
</div>
<div class="editor-label">
#Html.LabelFor(m => m.MyTestViewModel.ZipCode)
</div>
<div class="editor-field">
#Html.EditorFor(m => m.MyTestViewModel.ZipCode)
#Html.ValidationMessageFor(m => m.MyTestViewModel.ZipCode)
</div>
<div class="editor-label">
#Html.LabelFor(m => m.MyTestViewModel.ContactName)
</div>
<div class="editor-field">
#Html.EditorFor(m => m.MyTestViewModel.ContactName)
#Html.ValidationMessageFor(m => m.MyTestViewModel.ContactName)
</div>
<div class="editor-label">
#Html.LabelFor(m => m.MyTestViewModel.Email)
</div>
<div class="editor-field">
#Html.EditorFor(m => m.MyTestViewModel.Email)
#Html.ValidationMessageFor(m => m.MyTestViewModel.Email)
</div>
<div class="editor-label">
#Html.LabelFor(m => m.MyTestViewModel.BookDescription)
</div>
<div class="editor-field">
#Html.EditorFor(m => m.MyTestViewModel.BookDescription)
#Html.ValidationMessageFor(m => m.MyTestViewModel.BookDescription)
</div>
<div id="HCBudget" class="validation">
<label for="budgethealth">Budget Health</label>
#Html.RadioButton("Answer", "Red")
#Html.RadioButton("Answer", "Yellow")
#Html.RadioButton("Answer", "Green")
#Html.ValidationMessageFor(m => m.MyTestViewModel.Answer)
</div>
<input type="submit" value="Request Book" />
</fieldset>
}
Question: How do you guys handle validation with models used in a viewmodel.
Before I used this in a viewmodel everything was working well. By the time I used a viewmodel
validation stopped working.
Here is what the post action looks like.
public ActionResult RequestABook()
{
return View();
}
[HttpPost]
public ActionResult RequestABook(RequestABook quote)
{
return View();
}

Answer 1

It would help greatly if you posted your POST action. However, generally, I can say that validation is only run on related class instances if they are non-null. So, unless a value is posted for at least one of the properties on MyTestViewModel, it will not be instantiated by the modelbinder (MyTestViewModel will be null), and validation on its properties will not be run.
You can fix this scenario by always instantiating the MyTestViewModel property, either via the constructor of your view model or, probably better, using a custom getter and setter:
Constructor
public class RequestViewModel
{
public RequestViewModel()
{
MyTestViewModel = new RequestABook();
}
...
}
Custom Getter and Setter
private RequestABook myTestViewModel;
public RequestABook MyTestViewModel
{
get
{
if (myTestViewModel == null)
{
myTestViewModel = new RequestABook();
}
return myTestViewModel;
}
set { myTestViewModel = value; }
}