Exclude Property on Update in Entity Framework

I've been looking for a proper way to mark a property to NOT be changed when updating a model in MVC.

For example, let's take this small model:

class Model
{
    [Key]
    public Guid Id {get; set;}
    public Guid Token {get; set;}

    //... lots of properties here ...
}

then the edit method MVC creates looks like this:

[HttpPost]
public ActionResult Edit(Model model)
{
    if (ModelState.IsValid)
    {
        db.Entry(model).State = EntityState.Modified;
        db.SaveChanges();
        return RedirectToAction("Index");
    }
    return View(model);
}

now if my View does not contain the Token, it will be nullified through that edit.

I'm looking for something like this:

db.Entry(model).State = EntityState.Modified;
db.Entry(model).Property(x => x.Token).State = PropertyState.Unmodified;
db.SaveChanges();

The best way so far I found is to be inclusive and set all properties I want included by hand, but I really only want to say which ones to be excluded.

---

we can use like this

 db.Entry(model).State = EntityState.Modified;
 db.Entry(model).Property(x => x.Token).IsModified = false;
 db.SaveChanges();

it will update but without Token property

---

Create new model that will have limited set of properties that you want to update.

Ie if your entity model is:

public class User
{
    public int Id {get;set;}
    public string Name {get;set;}
    public bool Enabled {get;set;}
}

You can create custom view model that will allow user to change Name, but not Enabled flag:

public class UserProfileModel
{
   public int Id {get;set;}
   public string Name {get;set;}
}

When you want to do database update, you do the following:

YourUpdateMethod(UserProfileModel model)
{
    using(YourContext ctx = new YourContext())
    { 
        User user = new User { Id = model.Id } ;   /// stub model, only has Id
        ctx.Users.Attach(user); /// track your stub model
        ctx.Entry(user).CurrentValues.SetValues(model); /// reflection
        ctx.SaveChanges();
    }
}

When you call this method, you will update the Name, but Enabled property will remain unchanged. I used simple models, but I think you'll get the picture how to use it.

---

I guess you don't want the property to be changed just in some cases, because if you are not going to use it never in your application, just remove it from your model.

In case you want to use it just in some scenarios and avoid its "nullification" in the case above, you can try to:

Hide the parameter in the view with HiddenFor:

@Html.HiddenFor(m => m.Token)

This will make your original value to be kept unmodified and passed back to the controller.

Use TryUpdateModel : http://msdn.microsoft.com/en-us/library/dd460189(v=vs.108).aspx

Load again your object in the controller from your DBSet and run this method. You can specify both a white list and a blacklist of parameters that shall or shall not be update.

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