Required ModelValidation just for new objects ASP.NET MVC - asp.net-mvc-3

Question

I have this issue since yesterday.
In my User model I have a [NotMapped] called "ConfirmPassword". I don´t save it on the database but I use it on my Create form as a always to validate the data input for new users.
Since than, it´s ok. The problem is on my [HttpPost] Edit action. I should be able to edit some user's data without type and confirm the password. I use both Password and ConfirmPassword as a way to confirm the old password and informe the new one, if I wanna change the password. But, if I don´t, I leave them blank.
I have used already the code below to be able to pass the ModelState.IsValid() condition and it worked:
ModelState["Password"].Errors.Clear();
ModelState["ConfirmPassword"].Errors.Clear();
But, just before the db.SaveChanges(), as User user view model is considered, it has both properties empty and I got:
Property: ConfirmPassword Error: The field ConfirmPassword is invalid.
The question is: How could I skip de Required model validation when I want to update an object?
I read already about custom ModelValidations with classes extending ValidationAttribute and
DataAnnotationsModelValidator but I am not doing it right.
Any idea? How could I create a custom model validation that checks if the UserId property is null or not. It´s a nice way to check if I'm in Create or Edit action.
Thanks,
Paulo

Answer 1

Using the domain objects as your ViewModel will leads you to a condition of less scalability. I would opt for seperate ViewModels specific for the Views. When i have to save the data i map the ViewModel to the Domain model and save that. In your speciific case, i would create 2 ViewModels
public class CustomerViewModel
{
public string FirstName { set;get;}
public string LastName { set;get;}
}
And i will Have another ViewModel which inherits from the above class, for the Create View
public class CustomerCreateViewModel :CustomerViewModel
{
[Required]
public string Password { set;get;}
[Required]
public string ConfirmPassword { set;get;}
}
Now in my Get actions, i use this ViewModel
public ActionResult Create()
{
var vm=new CustomerCreateViewModel();
return View(vm);
}
and of course my View(create.cshtml) is now binded to this ViewModel
#model CustomerCreateViewModel
<h2>Create Csustomer</h2/>
//Other form stuff
Similarly for My Edit Action,
public ActionResult Edit(int id)
{
var vm=new CustomerViewModel();
var domainCustomer=repo.GetCustomerFromID(id);
if(domainCustomer!=null)
{
//This manual mapping can be replaced by AutoMapper.
vm.FirstName=domainCustomer.FirstName;
vm.LastName=domainCustomer.LastName;
}
return View(vm);
}
This view is bounded to CustomerViewModel
#model CustomerViewModel
<h2>Edit Info of #Model.FirstName</h2>
//Other form stuff
In your POST Actions, Map it back to the Domain object and Save
[HttpPost]
public ActionResult Create(CustomerCreateViewModel model)
{
if(ModelState.IsValid)
{
var domainCust=new Customer();
domainCust.FirstName=model.FirstName;
repo.InsertCustomer(domainCust);
//Redirect if success (to follow PRG pattern)
}
return View(model);
}
Instead of writing the Mapping yourself, you may consider using AutoMapper library to do it for you.