Why I can't pass this model to a controller in ASP.NET MVC

Question

Why i can't pass this model to a controller in ASP.NET MVC?

This is my View:

@model Pro.WebUI.ViewModels.DataItemVm

<div>
    <table class="table">
        <tr>
            <th>
                @Html.DisplayNameFor(model => model.FirstSetList.FirstOrDefault().Name)
            </th>            
            <th>
                @Html.DisplayNameFor(model => model.FirstSetList.FirstOrDefault().Amount)
            </th>
        </tr>
        @foreach (var item in Model.FirstSetList)
        {
            <tr>
                <td>
                    @Html.DisplayFor(modelItem => item.Name)
                </td>
                <td>
                    @Html.TextBoxFor(modelItem => item.Amount)
                </td>
            </tr>
        }
    </table>
    <hr/>
    <div>
        @using (Html.BeginForm())
        {
            @Html.HiddenFor(model => model.FirstSetList)
            <input type="submit" value="Confirm"/>
        }
    </div>
</div>

After I click Confirm button - this method receives model with Count = 0;

public ActionResult FirstSet(DataItemVm model)
    {
     ...
    }

Of course my ViewModel DataItemVm has list:

public class DataItemVm
    {
     public List<FirstSetViewModel> FirstSetList { get; set; }
    }

So it looks like that problem is only at view. Maybe BeginForm should be in other place? However HiddenFor should send be enough to send this model.

I'm having this very same problem when my model is a Tuple. Solved it using a FormCollection as parameter for the post method — Vitor Rigoni, Mar 18 '16 at 12:51
What kind of HTML is generated? I'm guessing `HiddenFor(model => model.FirstSetList)` doesn't know how to actually represent a list of `FirstSetViewModel` in a single hidden input. It doesn't simply serialize it or something. You probably need a create a specific edit-template for it. — Mark, Mar 18 '16 at 12:54

Red · Accepted Answer · 2016-03-18T13:20:53.003

Change @foreach cycle to for - ASP.NET MVC uses indexers to generate correct ids and names for elements, so you should use @Html.TextBoxFor(x=>x.Array[index]) to correctly generate html for your collections.

This cycle:

@foreach (var item in Model.FirstSetList)
{
    <tr>
        <td>
            @Html.DisplayFor(modelItem => item.Name)
        </td>
        <td>
            @Html.TextBoxFor(modelItem => item.Amount)
        </td>
    </tr>
}

Should instead look like this:

@for (var i = 0; i < Model.FirstSetList.Length; i++)
{
    <tr>
        <td>
            @Html.DisplayFor(model => model.FirstSetList[i].Name)
            @Html.HiddenFor(model => model.FirstSetList[i].Name) //otherwise name won't be returned to controller
        </td>
        <td>
            @Html.TextBoxFor(model=> model.FirstSetList[i].Amount)
        </td>
    </tr>
}

Another issue is - markup for the data that you want to be sent to the controller should be put inside @using (Html.BeginForm()){//put it here} block.

Check out this post about model binding in ASP.NET MVC: http://haacked.com/archive/2008/10/23/model-binding-to-a-list.aspx/

Thank you! By the way you forgot surround it with beginform. Correct it if you can - it may help someday. — DiPix, Mar 18 '16 at 13:19
Do you know why button is shown above table instead under Table? — DiPix, Mar 18 '16 at 13:32
@DiPix you have probably put in inside your `` tag. If not, check your layouts using developer console in your current browser. — Red, Mar 18 '16 at 13:39

Why I can't pass this model to a controller in ASP.NET MVC

1 Answers1