binding dropdown list in MVC - asp.net-mvc

Question

Hi I am trying to Bind my dropdown list in MVC from a model.
Here is my model
[Table("FileConfig")]
public class FileConfigModel
{
[Key]
[Display(Name = "File Congif ID")]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int FileConfigId { get; set; }
....
[Display(Name = "Description")]
public string Description { get; set; }
}
Here is my getall method in the controller:
public List<FileConfigModel> GetAll()
{
return db.FileConfigModels.ToList();
}
Then I am calling it from my another controller
public ActionResult Create()
{
var fileConfigListEntries = new FileConfigController().GetAll()
.Select(fc => new SelectListItem
{
Value = fc.FileConfigId.ToString(),
Text = fc.Description,
Selected = false
});
ViewBag.FileConfigEntires = fileConfigListEntries;
return View();
}
And here is my view:
#Html.LabelFor(model => model.FileConfigId, new { #class = "control-label col-md-2" })
<div class="col-md-10">
#Html.DropDownListFor(model => model.FileConfigId, ViewBag.FileConfigEntires as SelectList, "-Select File Config")
#Html.ValidationMessageFor(model => model.FileConfigId)
</div>
However, I've been keep getting error saying
"There is no ViewData item of type 'IEnumerable' that has the key 'FileConfigId'.."
Could someone please help me and tell me what I've missed.

Answer 1

Your query for fileConfigListEntries (i.e. ..Select(fc => new SelectListItem{ .. }) returns IEnumerable<SelectListItem>
In the view, you then try and convert that to typeof SelectList using ViewBag.FileConfigEntires as SelectList
SelectList is IEnumerable<SelectListItem>, but IEnumerable<SelectListItem> is not SelectList, therefore the conversion fails, and the 2nd parameter of DropDownListFor() is null. When the 2nd parameter is null, the method expects the 1st parameter to be IEnumerable<SelectListItem> which it is not, hence the exception.
Change your code to
#Html.DropDownListFor(m => m.FileConfigId, ViewBag.FileConfigEntires as IEnumerable<SelectListItem>, ... )
or
#Html.DropDownListFor(model => model.FileConfigId, (IEnumerable<SelectListItem>)ViewBag.FileConfigEntires, ... )
Side note There is no point setting Selected = false in the .Select clause - its false by default, but in any case, its ignored when binding to a model property (its the value of the property which determines what is selected)

Answer 2

Possible reason of above error could be variable fileConfigListEntries is null or not got the data from dbcontext.
As drop down list is bounded with null or collection with no elements error coming as "There is no ViewData item of type 'IEnumerable' that has the key 'FileConfigId'.."
I suggest replace fileConfigListEntries view bag data with hard-coded data and see error disappears.