Why is my ViewModel empty on [HttpPost] ?. NET MVC 3

Question

I am trying my best to use ViewModels correctly in my web application, but I am having various problems. One of them, if I set a breakpoint immediately after publishing using the Create action, my viewModel did not save any of my form values. I have to do something wrong, but I have tried several things. Including the code below, where I call the form elements the same as the viewModel fields to see if this helps.

I am also interested in which particular properties in your viewmodel should represent. I have seen people use different things in blog posts and much more.

If the view will display a selection list, I get the impression that the viewmodel should have an IEnumerable SelectListItem for this, as shown below. However, I have seen people use the IEnumerable Entity to represent a type that represents a select list.

Can anyone shed some light on this for me? Yesterday I gave up all my business logic to start a new job and try and do it right.

My ViewModel:

public class ServerCreateViewModel
{
    public int Id { get; set; }

    // CompanyName represents a field in the Company model. I did this to see if
    // it would help with model binding. Beforehand it was Companies to represent the type. I've done the same for the rest of them, so I wont comment on this again.
    public IEnumerable<SelectListItem> CompanyName { get; set; }

    // Represents the Game model.
    public IEnumerable<SelectListItem> GameTitle { get; set; }

    //Represents the Location model, etc...
    public IEnumerable<SelectListItem> City { get; set; }
    public IEnumerable<SelectListItem> NumberOfPlayers { get; set; }
    public IEnumerable<SelectListItem> CurrencyAbbreviation { get; set; }
}

My Controller action:

    public ActionResult Create()
    {
        var viewModel = new ServerCreateViewModel();

        viewModel.CompanyName = new SelectList(_dataService.Companies.All(), "Id", "CompanyName");
        viewModel.GameTitle = new SelectList(_dataService.Games.All(), "Id", "GameTitle");
        viewModel.City = new SelectList(_dataService.Locations.All(), "Id", "City");
        viewModel.NumberOfPlayers = new SelectList(_dataService.ServerPlayers.All(), "Id", "NumberOfPlayers");

        return View(viewModel);
    } 

    [HttpPost]
    public ActionResult Create(FormCollection collection, ServerCreateViewModel viewModel)
    {
        try
        {      // I put a breakpoint in here to check the viewModel values.
               // If I dont pass the viewModel into the constructor, it doesnt exist.
               // When I do pass it in, its empty.
            return Content("Success");
        }
        catch
        {
            return Content("Fail");
        }
    }  

My view:

@model GameserverCompare.ViewModels.Server.ServerCreateViewModel


@using (Html.BeginForm())
{
@Html.ValidationSummary(true)
<fieldset>
    <legend>Server</legend>
    @Html.HiddenFor(m => m.Id)
     <div class="editor-label">
        @Html.LabelFor(model => model.CompanyName)
    </div>
    <div class="editor-field">
        @Html.DropDownListFor(m => Model.CompanyName, Model.CompanyName)
        @Html.ValidationMessageFor(model => model.CompanyName)
    </div>
     <div class="editor-label">
        @Html.LabelFor(model => model.GameTitle)
    </div>
    <div class="editor-field">
        @Html.DropDownListFor(m => Model.GameTitle, Model.GameTitle)
        @Html.ValidationMessageFor(model => model.GameTitle)
    </div>
    <div class="editor-label">
        @Html.LabelFor(model => model.City)
    </div>
    <div class="editor-field">
        @Html.DropDownListFor(m => Model.City, Model.City)
        @Html.ValidationMessageFor(model => model.City)
    </div>
    <div class="editor-label">
        @Html.LabelFor(model => model.NumberOfPlayers)
    </div>
    <div class="editor-field">
        @Html.DropDownListFor(m => Model.NumberOfPlayers, Model.NumberOfPlayers)
        @Html.ValidationMessageFor(model => model.NumberOfPlayers)
    </div>
    <p>
        <input type="submit" value="Create" />
    </p>

</fieldset>
}   

Answer 1

Since you use the SelectList properties in the form model, you will need to have a different model to represent the selected values ​​in these lists:

public class ServerCreatePostbackModel
{
    public int Id { get; set; }

    // CompanyName represents a field in the Company model. 
    public string CompanyName { get; set; }

    // Represents the Game model.
    public string GameTitle { get; set; }

    //Represents the Location model, etc...
    public string City { get; set; }
    public int NumberOfPlayers { get; set; }
    public string CurrencyAbbreviation { get; set; }
}

HttpPost .

, HiddenFor Id, .