Dropdownlist value is null after posting to controller in ASP.NET MVC

Question

I can get all Roles plus actually Role for chosed user, but then When I posting to EditUser action, then Dropdownlist sends null. I mean When the form posts to my controller, I get null from DropDownList.

Here is my Model

public class EditUserViewModel
    {
      public string Id { get; set; }
      public string Name { get; set; }
      public string Email { get; set; }
      public List<SelectListItem> ApplicationRoles { get; set; }
      public string ApplicationRoleId { get; set; }
    }

Here is Action

[HttpGet]
            public async Task<ActionResult> EditUser(string id)
            {
                EditUserViewModel model = new EditUserViewModel();
                model.ApplicationRoles = RoleManager.Roles.Select(r => new SelectListItem
                {
                    Text = r.Name,
                    Value = r.Id
                }).ToList();


                if (!String.IsNullOrEmpty(id))
                {
                    ApplicationUser user = await UserManager.FindByIdAsync(id);
                    if (user != null)
                    {
                        var role = await UserManager.GetRolesAsync(user.Id);
                        var existingRole = role.First();
                        string existingRoleId = RoleManager.Roles.Single(r => r.Name == existingRole).Id;
                        model.Id = user.Id;
                        model.FirstName = user.FirstName;
                        model.ApplicationRoleId = existingRoleId;
                        ViewBag.RoleId = new SelectList(RoleManager.Roles, "Id", "Name", model.ApplicationRoleId); 
                    }
                }
                return PartialView("_EditUser", model);
            }

And here is DropDownlist from _EditUser.cshtml

<div class="form-group">
                @Html.Label("Role typ", htmlAttributes: new { @class = "control-label col-md-6" })
                <div class="col-md-12" title="Ange antal datorer som finns i lager">
                    @Html.DropDownList("RoleId", null, new { @class = "form-control" })
                    @Html.ValidationMessageFor(model => model.ApplicationRoles, "", new { @class = "text-danger" })
                </div>
            </div>

Getting null Only from DropDownList, not from @Html.EditorFor /Thanks in advance!

Show you model and the signature of the POST method (does your model really contain a property named RoleId? - based on the code in your get method your view code will be @Html.DropDownListFor(m => m.ApplicationRoleId, Model.ApplicationRoles) — user3559349
– user3559349, Commented Nov 24, 2017 at 20:40
@StephenMuecke Thank you. Now it's working . But I don't know how to accept your answer — Helen Tekie
– Helen Tekie, Commented Nov 24, 2017 at 20:49
I have not given an answer (and will not until you edit your question as I asked) — user3559349
– user3559349, Commented Nov 24, 2017 at 20:50
@StephenMuecke Aha Ok, now I have edited with ViewModel ..;) — Helen Tekie
– Helen Tekie, Commented Nov 24, 2017 at 20:54

user3559349 · Accepted Answer · 2017-11-24 21:03:23Z

Forms post back the name/value pairs of their successful form controls. Your generating a <select> element with name="RoleId" but you model does not contain a property named RoleId. Since you want to bind the selected option to the ApplicationRoleId role property, then you view needs to be

@Html.LabelFor(m => m.ApplicationRoleId)
@Html.DropDownListFor(m => m.ApplicationRoleId, Model.ApplicationRoles)
@Html.ValidationMessageFor(m => m.ApplicationRoleId)

Notes:

Your current @Html.Label(..) code does not create a label associated with your dropdownlist (clicking on it will not set focus)
The ValidationMessageFor() need to be applied to the property your binding to, not the SelectList
Delete you ViewBag.RoleId = new SelectList(..) code. Your have already assigned the selectlist to the ApplicationRoles property (and you should never need ViewBag if have a view model anyway)

Augusto · Accepted Answer · 2017-11-24 20:36:05Z

0

Because you are declare that only HttpGet methods are allow in that method of the controller. Thats why

answered Nov 24, 2017 at 20:36

Augusto

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1 Comment

Helen Tekie Over a year ago

Thank you guys all of you, it's working as @StephenMuecke responsed

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