CODEWITHSUNDEEP
objectasp.net-mvc-4viewcontrollerienumerable
Yuri
Yuri

Reputation: 4498

Viewmodel IEnumerable property is empty

I'm in the middle of making an ASP .NET MVC4 based app. I'm a complete newb in that field. The idea is quite simple - have a some members in DB, show them listed, select desired ones via check boxes and redirect to some other controller which would do something with the previously selected members.

Problem is passing the list of members from View to the Controller. I've thought it would work with ViewModel. It certainly works from Controller to the View, but not the other way.

My ViewModel:

public class MembersViewModel
{
    public IEnumerable<Directory_MVC.Models.Member> MembersEnum { get; set; }

    public string Test { get; set; }
}

Snippet of my Controller:

public class MembersController : Controller
{
    private MainDBContext db = new MainDBContext();

    public ActionResult Index()
    {
        var model = new Directory_MVC.ViewModels.MembersViewModel();

        // populating from DB
        model.MembersEnum = db.Members.Include(m => m.Group).Include(m => m.Mother).Include(m => m.Father);

        model.Test = "abc";

        return View(model);
    }

    [HttpPost]
    public ActionResult GoToSendEmail(Directory_MVC.ViewModels.MembersViewModel returnedStruct)
    {
        if (ModelState.IsValid)
        {
            // it is valid here
            return Redirect("http:\\google.com");
        }
    }

Snippet of my View:

@model Directory_MVC.ViewModels.MembersViewModel


@{
ViewBag.Title = "Members listing";

var lineCount = 0;
string lineStyle;
}

@using (Html.BeginForm("GoToSendEmail", "Members", FormMethod.Post))
{
<table>
@foreach (var item in Model.MembersEnum)
{
    lineCount++;

    // set styling
    if (lineCount % 2 == 1)
    {
        lineStyle = "odd-line";
    }
    else
    {
        lineStyle = "even-line";
    }

    <tr class="@lineStyle">
        <td>
            @Html.EditorFor(modelItem => item.Selected)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.FirstName)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.LastName)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Mother.FirstName) @Html.DisplayFor(modelItem => item.Mother.LastName)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Father.FirstName) @Html.DisplayFor(modelItem => item.Father.LastName)
        </td>
  <!-- other print-outs but not all properties of Member or Mother/father are printed -->
    </tr>
 }

</table>

<input type="submit" value="Send E-mail" />
}

The data are shown OK in the View. However, when I submit that form the returnedStruct.MembersEnum and Test string are both null in the Controller's method GoToSendEmail.

Is there a mistake or is there another possible way how to pass that members structure and check their Selected property?

Upvotes: 0

Views: 1098

Answers (2)

Yuri
Yuri

Reputation: 4498

Html.BeginCollectionItem() helper did the job - BeginCollectionItem.

Upvotes: 0

David Spence
David Spence

Reputation: 8079

Model binding to a collection works a little differently. Each item has to have an identifier so that inputs don't all have the same name. I've answered a similar question here.

@for (int i = 0; i < Model.MembersEnum.Count(); i++)
{
    @Html.EditorFor(modelItem => modelItem.MembersEnum[i].FirstName)
}

...which should render something like...

<input type="text" name="MembersEnum[0].FirstName" value="" />
<input type="text" name="MembersEnum[1].FirstName" value="" />
<input type="text" name="MembersEnum[2].FirstName" value="" />

...which should then populate the collection in your ViewModel when picked up by the controller...

public ActionResult GoToSendEmail(ViewModels.MembersViewModel model)

As mentioned in the other answer, I'd have a look at some related articles from Scott Hansleman and Phil Haack.

You also mentioned that your string called Test is null when you submit to your POST action. You haven't added a field for this property anywhere within your form, so there's nothing for the model binder to bind to. If you add a field for it within your form then you should see the value in the POST action:

@Html.EditorFor(modelItem => modelItem.Test)

Upvotes: 1

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