Asp.NET MVC Razor DropDownList and document with table part - entity-framework

Question

I need to make a drop-down list box, which selects data from the related table.
I've used an example from MSDN, but it doesn't work.
public ActionResult Create()
{
TypeItemsDropDownList();
return View(new Item());
}
//
// POST: /Item/Create
[HttpPost]
public ActionResult Create([Bind(Include = "idItem,nameItem,priceItem,quantity,inStock,descrItem,idTypeItem")]Item item)
{
try
{
if (ModelState.IsValid)
{
iac.StoreNewItem(item);
return RedirectToAction("Index");
}
}
catch (System.Data.DataException)
{
//Log the error (add a variable name after DataException)
ModelState.AddModelError("", "Unable to save changes. Try again, and if the problem persists, see your system administrator.");
}
TypeItemsDropDownList(item.idTypeItem);
return View(item);
}
private void TypeItemsDropDownList(object selectedTypeItem = null)
{
cabproddbEntities db = new cabproddbEntities();
var typeQuery = from d in db.TypeItem
orderby d.nameTypeItem
select d;
ViewBag.idTypeItem = new SelectList(typeQuery, "idTypeItem", "nameTypeItem", selectedTypeItem);
}
The error occurs here:
<div class="editor-label">
<label class="control-label col-md-2" for="idTypeItem">Тип продукции</label>
</div>
<div class="editor-field">
#Html.DropDownList("idTypeItem", String.Empty)
#Html.ValidationMessageFor(model => model.idTypeItem)
</div>
on this line: #Html.DropDownList("idTypeItem", String.Empty)
The table TypeItem has the data.
The thrown exception is: System.Data.EntityCommandExecutionException with the following details:
The text, ntext, and image data types cannot be compared or sorted, except when using IS NULL or LIKE operator.

Answer 1

Your issue is you are not linking your SelectList to the drop down. Use the DropDownListFor() helper and reference your select list in it. As shown below.
Your naming conventions are a little off also and this might be leading you into confusion.
#Html.DropDownListFor(m => Model.selectedItem, ViewBag.idTypeItem)