Empty Enumeration in post method

Question

I have this view

@model IEnumerable<ViewModelRound2>

... <snip> ...

@{
    using (Html.BeginForm(new { round1Ring3Bids = Model }))
    {
        if (Model != null && Model.Count() > 0)
        {
                ... <snip> ...

                @for (var x = 0; x < Model.Count(); x++)
                {
                    ViewModelRound2 viewModelRound2 = Model.ElementAt(x);
                    Bid bid = viewModelRound2.Bid;

                    string userName = @bid.User.Invitation.Where(i => i.AuctionId == bid.Lot.Lot_Auction_ID).First().User.User_Username;

                    <tr>
                        <td>
                            @userName
                        </td>
                        <td>
                            @bid.Bid_Value
                        </td>
                        <td>
                            @Html.EditorFor(c => c.ElementAt(x).SelectedForRound2) 
                        </td>
                    </tr>
                }

            </table>

            <div class="buttonwrapper2">
                <input type="submit" value="Select"/>              
            </div>
        }
    }
}

I have a post method that this goes to when the submit button is hit

[HttpPost]
        public ActionResult Round2Manager(IEnumerable<ViewModelRound2> round1Ring3Bids)

Problem is that the enumeration is always empty. Why is this?

Darin Dimitrov · Accepted Answer · 2012-06-18T14:25:33.227

Problem is that the enumeration is always empty. Why is this?

Because you are not respecting the wire format that the default model binder expects to bind collections.

The following:

@Html.EditorFor(c => c.ElementAt(x).SelectedForRound2)

generates absolutely wrong names for your input fields.

I would recommend you using editor templates to avoid those kind of problems:

@model IEnumerable<ViewModelRound2>

@using (Html.BeginForm())
{
    if (Model != null && Model.Count() > 0)
    {
        <table>
            @Html.EditorForModel()
        </table>
        <div class="buttonwrapper2">
            <input type="submit" value="Select"/>              
        </div>
    }
}

and then define a custom editor template for the ViewModelRound2 type (~/View/Shared/EditorTemplates/ViewModelRound2.cshtml) which will automatically be rendered for each element of this collection:

@model ViewModelRound2
@ {
    string userName = Model.Bid.User.Invitation.Where(
        i => i.AuctionId == Model.Bid.Lot.Lot_Auction_ID
    ).First().User.User_Username;
}

<tr>
    <td>
        @userName
    </td>
    <td>
        @Model.Bid.Bid_Value
    </td>
    <td>
        @Html.EditorFor(c => c.SelectedForRound2) 
    </td>
</tr>

You will now notice how the text input fields have correct names:

name="[0].SelectedForRound2"
name="[1].SelectedForRound2"
name="[2].SelectedForRound2"
...

Compare this with your initial values.

Empty Enumeration in post method

1 Answers1