Delete value by updating field - asp.net-mvc-4

Question

I have this:
View:
#using (Html.BeginForm())
{
#Html.AntiForgeryToken()
<div class="form-horizontal">
<h4>Bycicle</h4>
<hr />
#Html.ValidationSummary(true)
#Html.HiddenFor(model => model.id)
<div class="form-group">
<label class="control-label col-md-2" for="BycicleID">Mark</label>
<div class="col-md-10">
#Html.DropDownList("BycicleID", String.Empty)
#Html.ValidationMessageFor(model => model.id)
</div>
</div>
The controller:
public async Task<ActionResult> Edit(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
Bycicle bycicle = await db.Bycicles.FindAsync(id);
if (bycicle == null)
{
return HttpNotFound();
}
ViewBag.id = new SelectList(db.Bycicles, "BycicleID", "Mark", bycicle.id);
//ViewBag.Color = new SelectList(db.Bycicles, "Color", "Color", bycicle.Color);
//ViewBag.Weight = new SelectList(db.Bycicles, "Weight", "Weight", bycicle.Weight);
//ViewBag.Height = new SelectList(db.Bycicles, "Height", "Height", bycicle.Height);
return View(bycicle);
}
// POST: Bycicle/Edit/5
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<ActionResult> Edit(
[Bind(Include = "id, Mark, Color, Weight,Height")]
Bycicle bycicle)
{
if (ModelState.IsValid )
{
db.Entry(bycicle).State = EntityState.Modified;
await db.SaveChangesAsync();
return RedirectToAction("Index");
}
ViewBag.id = new SelectList(db.Bycicles, "id", "Mark", bycicle.id);
return View(bycicle);
}
and the Model:
public class Bycicle
{
public int id { get; set; }
// [Column("Mark")]
public string Mark { get; set; }
public string Color { get; set; }
public string Weight { get; set; }
public string Height { get; set; }
public DateTime? LastTimeChecked { get; set; }
}
But so I can update the other values(Color, Weight, Height) But the Mark name will be deleted if I press save in the Update view. I also checked the db and the Mark value is gone after Update. But If I just press on Edit(update) Then first I see the value(Mark) in the dropdownlist, but after save the mark value is gone. Even if I didnt changed the Mark value in the Update view.
I just cant figure what is wrong.
Thank you!!
Oke,
I did understand it was a type mistake,
But what do you mean with the dropdonlists are not correct? Because you dont have a infinite mark list of bycicles. So that Is why I choose to make a dropdownlist with all the marks and the colors and the sizes. Because an admin fill in the marks, sizes, etc and then the user can select a mark, color, etc. But how will you design the different properties?
I dont have seperate tables for color, mark, etc. But is that necessary?
Thank you

Answer 1

Your not binding anything to the property Mark (what you have shown is bound to the ID property). Preferably the names of your select lists should not be the same as your properties.
In the controller
ViewBag.MarkList = new SelectList(db.Bycicles, "BycicleID", "Mark");
and in the view
#model YourAssembly.Bycicle
....
<div class="form-group">
#Html.LabelFor(m => m.Mark)
<div class="col-md-10">
#Html.DropDownListFor(m => m.Mark, (SelectList)ViewBag.MarkList)
#Html.ValidationMessageFor(m => m.Mark)
</div>
</div>
Note, since you binding all properties, you do not need [Bind(Include = "id, Mark, Color, Weight,Height")]
Edit
While passing values by ViewBag works, I recommend you use view models and strongly typed helpers so you have intellisense support as well as all the other benefits of using view models.
public class BycicleVM
{
public int id { get; set; }
// other properties of Bycicle that you want to edit
public SelectList MarkList { get; set; }
// other select lists
}
then assign the select lists to the view model rather than ViewBag