DropDown list [asp.net core 2.0] - entity-framework

Question

Hi im having problem with my view
as you can see there is an input and a select option
<div class="form-group">
<label asp-for="DomWasLoc" class="control-label"></label>
<input asp-for="DomWasLoc" class="form-control" id="firstname" name="firstname" />
<select class="form-control"
id="name" name="name"
asp-items="#(new SelectList(ViewBag.LocationList, "LocName","LocName"))">
<option value="">- Select -</option>
</select>
<span asp-validation-for="DomWasLoc" class="text-danger"></span>
</div>
every time you select an item on on the dropdownList the selected item value is inputted in the input box.
but every time i click submit i always shows this error
AspNetCore._Views_DomesticWastes_Create_cshtml+d__25.MoveNext() in Create.cshtml
+
asp-items="#(new SelectList(ViewBag.LocationList, "LocName","LocName"))">
what should i do so that when i click submit it ignore the select and just add the data from input box?
thanks in advance guys! :)

Answer 1

There is no need to combine input and select for the same field DomWasLoc. You could bind the DomWasLoc directly to select.
A demo code like below:
<div class="form-group">
<label asp-for="DomWasLoc" class="control-label"></label>
#*<input asp-for="DomWasLoc" class="form-control" />*#
<select class="form-control"
asp-for="DomWasLoc"
asp-items="#(new SelectList(ViewBag.LocationList, "LocName","LocName"))">
<option value="">- Select -</option>
</select>
<span asp-validation-for="DomWasLoc" class="text-danger"></span>
</div>
Update:
Complte Code:
1. Model
public class Location
{
public int Id { get; set; }
public string LocName { get; set; }
}
public class DomesticWaste
{
public int Id { get; set; }
public string DomWasLoc { get; set; }
}
Controller
// GET: DomesticWastes/Create
public IActionResult Create()
{
List<Location> locationlist = new List<Location>() {
new Location{ Id = 1, LocName = "L1" },
new Location{ Id = 2,LocName = "L2" },
new Location{ Id = 3,LocName = "L3" }
};
ViewBag.LocationList = locationlist;
return View();
}
// POST: DomesticWastes/Create
// To protect from overposting attacks, please enable the specific properties you want to bind to, for
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Create([Bind("Id,DomWasLoc")] DomesticWaste domesticWaste)
{
if (ModelState.IsValid)
{
_context.Add(domesticWaste);
await _context.SaveChangesAsync();
return RedirectToAction(nameof(Index));
}
return View(domesticWaste);
}