Question

I hope someone can help with this one. I have three Model classes like this:

public class Provider
{
    public Guid ProviderId { get; set; }
    public string Name { get; set; }

    public Guid LocationId { get; set; }

    public virtual Location Location { get; set; }
}

public class Location
{
    public Guid LocationId { get; set; }
    public string NameOrCode { get; set; }
    public string Description { get; set; }
    public string StreetNumber { get; set; }
    public string StreetAddress1 { get; set; }
    public string StreetAddress2 { get; set; }
    public string City { get; set; }

    public int? StateId { get; set; }

    public string Zip { get; set; }
    public string ContactPhone { get; set; }

    public virtual State State { get; set; }
}

public class State
{
    public int StateId { get; set; }
    public string Name { get; set; }
    public string Abbreviation { get; set; }
}

As you can see, a Provider has a Location (separate class for reuse elsewhere), and a Location has a State (which is null until selected).

My Controller looks like this for my Create methods:

public class ProviderController : BaseController
{
    private SetupContext db = new SetupContext();

    // other CRUD methods ...

    //
    // GET: /Provider/Create

    public ActionResult Create()
    {
        Location location = new Location() 
        { 
            LocationId = Guid.NewGuid(), 
            NameOrCode = Resources.BillingLocation,
            Description = Resources.BillingLocationDescription
        };
        Provider provider = new Provider()
        {
            ProviderId = Guid.NewGuid(),
            LocationId = location.LocationId,
            Location = location
        };
        ViewBag.StateId = new SelectList(db.States, "StateId", "Name", provider.Location.StateId);

        return View(provider);
    } 

    //
    // POST: /Provider/Create

    [HttpPost]
    public ActionResult Create(Provider provider)
    {
        if (ModelState.IsValid)
        {
            db.Locations.Add(provider.Location);
            db.Providers.Add(provider);
            db.SaveChanges();

            return RedirectToAction("Index");  
        }

        ViewBag.StateId = new SelectList(db.States, "StateId", "Name", provider.Location.StateId);
        return View(provider);
    }

    // other CRUD methods ... 
}

Finally, my View looks like this:

<div class="editor-label">
    @Html.LabelFor(model => model.Location.StateId, @Resources.Location_State_Display_Name)
</div>
<div class="editor-field">
    @Html.DropDownList("StateId", @Resources.ChooseFromSelectPrompt)
    @Html.ValidationMessageFor(model => model.Location.StateId)
</div>

My problem is that the state the user selects in the DropDownList never gets set on my Model on the Create POST. I have similar code in my Edit View and the state is populated correctly in that View (that is, the state associated with an existing Provider.Location shows selected in the DropDownList for the user to edit if desire), but in both the Create and the Edit Views the selection made by the user is never registered in my Model (specifically the Provider.Location.StateId) coming in from the POST.

Looking at the HTML produced I see this:

<div class="editor-label">
    <label for="Location_StateId">State/Territory</label>
</div>
<div class="editor-field">
    <select id="StateId" name="StateId"><option value="">[Choose]</option>
        <option value="1">Alabama</option>
        <option value="2">Alaska</option>
        <!-- more options ... -->
    </select>
    <span class="field-validation-valid" data-valmsg-for="Location.StateId" data-valmsg-replace="true"></span>
</div>

I suspect I need to somehow convey the Location.StateId relationship instead of just StateId as I see above but I can’t figure out the correct syntax to do that. I’ve tried changing my ViewBag dynamic property to Location_StateId like this:

ViewBag.Location_StateId = new SelectList(db.States, "StateId", "Name", provider.Location.StateId);

And the DropDownList in my View like this:

@Html.DropDownList("Location_StateId", @Resources.ChooseFromSelectPrompt)

I figured then perhaps that notation would work because the label beside my DropDownList was rendered as:

<div class="editor-label">
    <label for="Location_StateId">State/Territory</label>
</div>

This attempt did not work. Can you help me out?

Thanks in advance.

Answer 1

@Html.DropDownList("Location.StateId", @Resources.ChooseFromSelectPrompt)

Also the following line doesn’t do anything useful:

ViewBag.StateId = new SelectList(db.States, "StateId", "Name", provider.Location.StateId);

You are assigning a SelectList to something that is supposed to be a scalar property. You probably wanted to pass the collection as ViewBag:

ViewBag.States = new SelectList(db.States, "StateId", "Name", provider.Location.StateId);

and then in the view:

@Html.DropDownList("Location.StateId", (SelectList)ViewBag.States)