c# mvc model binding nested lists

Question

I got a problem with my model binding. Got here following models:

public class RoomScan
{
    public RoomScan() { }

    public RoomScan(Guid id)
    {
        Room_ID = id;
        Assets = new List<AssetScanModel>();
    }
    //public Guid Soll_ID { get; set; }
    public Guid Room_ID { get; set; }
    public List<AssetScanModel> Assets { get; set; }

    [Display(Name = "Barcode", ResourceType = typeof(Dictionary))]
    public string Barcode { get; set; }

    [Display(Name = "RFID", ResourceType = typeof(Dictionary))]
    public string RFID { get; set; }
}

public class AssetScanModel
{
    public AssetScanModel(Asset asset)
    {
        Asset = asset;
        Scanned = false;
        CheckIn = false;
    }

    public Asset Asset { get; set; }

    [Display(Name = "Scanned", ResourceType = typeof(Dictionary))]
    public bool Scanned { get; set; }

    [Display(Name = "CheckIn", ResourceType = typeof(Dictionary))]
    public bool CheckIn { get; set; }
}

The View does list all the Assets:

using (Html.BeginForm("Scan", "Inventory", FormMethod.Post))
{
Html.HiddenFor(rs => rs.Room_ID);
Html.HiddenFor(rs => rs.Assets);

<div>
    <div class="editor-label">Barcode</div>
    <div class="editor-field"><input type="text" name="Barcode" value="@Model.Barcode" /></div>
</div>
<div>
    <div class="editor-label">RFID</div>
    <div class="editor-field"><input type="text" name="Barcode" value="@Model.RFID" /></div>
</div><br />

...

@for (int i = 0; i < Model.Assets.Count; i++)
{
    <tr>
        <td>@Html.DisplayFor(asm => asm.Assets[i].Asset.InventoryNumber)</td>
        <td>@Html.DisplayFor(asm => asm.Assets[i].Asset.Description)</td>
        <td>@Html.DisplayFor(asm => asm.Assets[i].Asset.Manufacturer)</td>
        <td>@Html.DisplayFor(asm => asm.Assets[i].Asset.Model)</td>
        <td>@Html.DisplayFor(asm => asm.Assets[i].Asset.SerialNumber)</td>
        <td>@Html.DisplayFor(asm => asm.Assets[i].Scanned)</td>
        <td>@Html.DisplayFor(asm => asm.Assets[i].CheckIn)</td>
    </tr>
}

I added the "Asset[i]" because I read somewhere it helps the default model binder to bind propperly (didn#t work)

My problem is: in my controller:

[HttpPost]
    public ActionResult Scan(RoomScan toVerify)

the List is empty (not null). I know this has to do with the model binder, but I am not familiar how to change it so it does work.

Answer 1

I have been using this for binding complex models with nested lists. I almost always replace the default model binder with this right off the bat...

A DefaultModelBinder that can update complex model graphs

I hope this helps you as much as it did me.

Answer 2

Try DisplayTemplates/EditorTemplates, create template for ur nested model type. In View write:

@Html.DisplayFor(asm => asm.Assets)

in DisplayTemplate (AssetScanModel.cshtml):

@model AssetScanModel

<tr>
    <td>@Html.DisplayFor(asm => asm.Asset.InventoryNumber)</td>
    <td>@Html.DisplayFor(asm => asm.Asset.Description)</td>
    <td>@Html.DisplayFor(asm => asm.Asset.Manufacturer)</td>
    <td>@Html.DisplayFor(asm => asm.Asset.Model)</td>
    <td>@Html.DisplayFor(asm => asm.Asset.SerialNumber)</td>
    <td>@Html.DisplayFor(asm => asm.Scanned)</td>
    <td>@Html.DisplayFor(asm => asm.CheckIn)</td>
</tr>