Question

I am trying to get my view to post a List back to the action however it keeps coming in as null.

So my Model has a List of WeightEntry objects.

Exercise Model

public class Exercise
{
    public List<WeightEntry> Entries { get; set; }
    public int ExerciseID { get; set; }
    public int ExerciseName { get; set; }
}

WeightEntry Model

public class WeightEntry
{
    public int ID { get; set; }
    public int Weight { get; set; }
    public int Repetition { get; set; }
}

My View contains the ExerciseName and a forloop of WeightEntry objects

@model Mymvc.ViewModels.Exercise
...
<span>@Model.ExerciseName</span>
@using (Html.BeginForm())
{
    @Html.ValidationSummary(true)
    <table class="left weight-record">
        <tr>
            <th>Reps</th>
            <th>Weight</th>
        </tr>
        @foreach (var item in Model.Entries)
        {
            <tr>
                <td>
                    @Html.EditorFor(x => item.Repetition)
                </td>
                <td>
                    @Html.EditorFor(x => item.Weight)
                </td>
            </tr>
        }
    </table>
    <input type="submit" value="Save" /> 
}

The Controller Action (Post) Does nothing at the moment. I am just trying to get the binding working before I add the save code.

[HttpPost]
public ActionResult WeightEntry(Exercise exercise)
{
    try
    {
        //Add code here to save and check isvalid    
        return View(exercise);
    }
    catch
    {
        return View(exercise);
    }
}

I have seen a few little tricks with adding a numerator to the form elements’ names used in MVC2 but I was wondering if MVC3 was any different? I was hoping it would all bind nicely with ID’s being 0 or null but instead the whole List is null when I inspect it after the form posts. Any help is appreciated.
Thanks.

Answer 1

Replace the following loop:

@foreach (var item in Model.Entries)
{
    <tr>
        <td>
            @Html.EditorFor(x => item.Repetition)
         </td>
         <td>
             @Html.EditorFor(x => item.Weight)
         </td>
     </tr>
}

with:

@for (var i = 0; i < Model.Entries.Count; i++)
{
    <tr>
        <td>
            @Html.EditorFor(x => x.Entries[i].Repetition)
         </td>
         <td>
             @Html.EditorFor(x => x.Entries[i].Weight)
         </td>
     </tr>
}

or even better, use editor templates and replace the loop with:

@Html.EditorFor(x => x.Entries)

and then define a custom editor template that will automatically be rendered for each element of the Entries collection (~/Views/Shared/EditorTemplates/WeightEntry.cshtml):

@model WeightEntry
<tr>
    <td>
        @Html.EditorFor(x => x.Repetition)
     </td>
     <td>
         @Html.EditorFor(x => x.Weight)
     </td>
 </tr>

The the generated input elements will have correct names and you will be able to successfully fetch them back in your POST action.