MVC Controller Post Method with ViewModel to Update EF Entities

MVC Controller Post Method with ViewModel to Update EF Entities

After a bunch of reading on best practices I am now using a viewmodel
which is customized for every view and my controller methods pass the
viewmodels to the view and then update the db.
I have my GET methods working properly using LINQ projection but I'm not
sure what to do in the POST method. If my viewmodel only contains the
properties that its view is updating, but an entry already exists in the
database for that particlar key, how to I update my EF model with the
viewmodel properties without having the get every property in the EF model
every time?
Here is my code:
ViewModel
public class GeneralViewModel
{
public string Title { get; set; }
public decimal? Proposal_Type_ID { get; set; }
public string User_Facility_ID { get; set; }
public IEnumerable<SelectListItem> ProposalTypes { get; set; }
}
Controller
public ActionResult General(int id)
{
var context = new PASSEntities();
var model = (from a in context.Proposals
where a.ID == id
select new GeneralViewModel()
{
User_Facility_ID = a.User_Facility_ID,
Title = a.Title,
Proposal_Type_ID = a.Proposal_Type_ID
}).SingleOrDefault();
var proposalTypes = context.Proposal_Types.Where(m =>
m.User_Facility_ID == model.User_Facility_ID).ToList();
model.ProposalTypes = proposalTypes.Select(m => new SelectListItem
{ Value = m.ID.ToString(), Text = m.Description }).ToList();
return PartialView(model);
}
[HttpPost]
public ActionResult General(int id, GeneralViewModel model)
{
try
{
var context = new PASSEntities();
var proposal = context.Proposals.Find(id);
proposal.Title = model.Title;
proposal.Proposal_Type_ID = model.Proposal_Type_ID;
context.Entry(proposal).State = System.Data.EntityState.Modified;
context.SaveChanges();
return PartialView();
}
catch
{
return View();
}
}
My Post method is working but I don't feel like this is the best way to do
it. The reason I did it this way was when I just newed up an EF Proposal
model and mapped it's properties to the viewmodel properties, it changed
my User_Facility_ID value to null because I didn't used it in my form.
So really I'm just looking for the best way to perform the POST.