Question

I have a model, ApplicantBranchList, that is used as a property in a larger model as follows:

[Display(Name = "Where would you want to work?")]
public ApplicantBranchList PreferedBranches { get; set; }

ApplicantBranchList:

public class ApplicantBranchList : ViewModel
{
    public ApplicantBranchItem HeaderItem { get; set; }
    public ApplicantBranchList()
    {
        HeaderItem = new ApplicantBranchItem();
    }
    public void MapFromEntityList(IEnumerable<ApplicantBranch> applicantBranches)
    {
        var service = new BranchService(DbContext);
        var selectedIds = applicantBranches.Select(b => b.BranchId);
        Items = service.ReadBranches()
                       .Where(i => !i.IsDeleted)
                       .Select(p => new ApplicantBranchItem { BranchName = p.Name, WillWorkAt = selectedIds.Contains(p.Id) });
    }
    public IEnumerable<ApplicantBranchItem> Items { get; set; }
}

ApplicantBranchList has its own editor template, and an inner editor template for each item in ApplicantBranchList:

Views/Shared/EditorTemplates/ApplicantBranchList.cshtml:

@model Comair.RI.UI.Models.ApplicantBranchList
<table>
    <tr>
        <th style="display: none;"></th>
        <th>
            @Html.DisplayNameFor(model => model.HeaderItem.BranchName)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.HeaderItem.WillWorkAt)
        </th>
    </tr>
    @foreach (var item in Model.Items)
    {
        @Html.EditorFor(m => item)
    }
</table>

Views/Shared/EditorTemplates/ApplicantBranchItem.cshtml:

@model Comair.RI.UI.Models.ApplicantBranchItem
<tr>
    <td style="display: none;">
        @Html.HiddenFor(m => m.BranchId)
    </td>
    <td>
        @Html.DisplayFor(m => m.BranchName)
    </td>
    <td>
        @Html.EditorFor(m => m.WillWorkAt)
    </td>
</tr>

This editor renders properly in the view, but in the post action:

public ActionResult Create(ApplicantProfileModel model)
{
    if (ModelState.IsValid)
    {
        var branches = model.PreferedBranches;

PreferedBranches.Items is null.

What am I doing wrong?

Answer 1

The problem is that ASP.NET can’t figure out how to bind to Model.Items property.

To to fix it replace:

public IEnumerable<ApplicantBranchItem> Items { get; set; }

with this:

public List<ApplicantBranchItem> Items { get; set; }

and instead of:

@foreach (var item in Model.Items)
{
   @Html.EditorFor(m => item)
}

use this one:

@for (var i = 0; i < Model.Items.Count; i++)
{
   @Html.EditorFor(model => model.Items[i]) // binding works only with items which are accessed by indexer
}