Question

I am developing an ASP.Net MVC 3 Web application and I am having some difficulties with getting the values from a checkboxlist. I have already read most of the questions on Stackoverflow around this area, however, I am still having some issues.

I have a ViewModel

public class ViewModelCheckBox
{
    public string Id { get; set; }
    public string Name { get; set; }
    public bool Checked { get; set; }
}

Another ViewModel which use the viewmodel above

public class ViewModelAssignSubSpeciality
{
    public ListItem Item { get; set; }
    public IList<ViewModelCheckBox> SpecialityList { get; set; }
}

Then in my controller

public ActionResult AssignSubSpeciality(int id)
{
        //Get a list of all sub-specialities
        var SpecialityList = _listService.GetListItemsByID(3).ToList();

        //Get a list of sub-specialities for the the passed in id, this is either the id of a speciality or grade
        IList<RelationshipSpecialitySub> assignedSpecialities = _listService.GetAssignedSubSpecialities(id).ToList();

        var checkBoxList = new List<ViewModelCheckBox>();

        foreach (ListItem item in SpecialityList)
        {
            ViewModelCheckBox chkBox = new ViewModelCheckBox { Id = item.listItemID.ToString(), Name = item.description };

            //If sub-speciality exists in assignedSpecialities list, then make checkbox checked
            foreach (var specilaity in assignedSpecialities)
            {
                if (specilaity.subID == item.listItemID)
                {
                    chkBox.Checked = true;
                }
                else
                {
                    chkBox.Checked = false;
                }
            }

            checkBoxList.Add(chkBox);
        }

        ViewModelAssignSubSpeciality viewModel = new ViewModelAssignSubSpeciality();
        viewModel.ListItem = _listService.GetListItemByID(id);
        viewModel.SpecialityList = checkBoxList;

        return View(viewModel);
    }

The code in the controller above is getting a list of all the possible checkbox list items, then getting a list of all the previously selected checkbox list items for which it sets the checked option to true.

My View then looks like this, looping over the SpecialityList and creating a checkbox for each item, and also setting its selected value to true if needs be.

<fieldset>
<legend>Specialities</legend>

@foreach (var item in Model.SpecialityList)
{
<input type="checkbox" id="@item.Id" name="@item.Name" value="@item.Id" @(item.Checked ? "checked" : "") />
<label for="@item.Id">@item.Name</label><br />
}

<input type="submit" value="Save Changes" class="sepH_b" />                                         

My HttpPost method in my controller then looks like this

    public ActionResult AssignSubSpeciality(ViewModelAssignSubSpeciality model)
    {
        //delete all sub-specialities in tbl relationshipSpecialitySub for List
        foreach (ViewModelCheckBox item in model.SpecialityList)
        {
                //_listService.DeleteSubSpecialityFromSpeciality(item.Id);
        }

        return RedirectToAction("ListItems", new { id = model.ListItem.listID });
    }

However, when I try to get the selected checkboxes in

model.SpecialityList

It us always null. I am not sure why it doesnt contain a list of ViewModelCheckBox.

Can anyone please help me with this?

Thank you.

Answer 1

I have an Enumerable of these in my view model

public class CheckBoxItem
{
   public string Code { get; set; }
   public bool IsChecked { get; set; }
   public string Label {get;set;}
}

I then use an editor template to display them on the page.

<p class="checkbox" style="display:inline">
<span style="margin-left:5px;">
    @Html.HiddenFor(x => x.Code)           
    @Html.CheckBoxFor(x => x.IsChecked)
</span>
@Html.LabelFor(x => x.IsChecked, Model.Label)
</p>

In the view I use the following to display them on the page.

@Html.EditorFor(m => m.MyEnumerableOfCheckBoxItem)

When the form is posted back the model is correctly bound.

Hope this helps.