Question

I have a model containing a couple of lists:

[Display(Name = "Facilities")]
public List<facility> Facilities { get; set; }

[Display(Name = "Accreditations")]
public List<accreditation> Accreditations { get; set; }

I populate these lists initially from my controller:

public ActionResult Register()
{
    var viewModel = new RegisterModel();

    viewModel.Facilities = m_DBModel.facilities.ToList();
    viewModel.Accreditations = m_DBModel.accreditations.ToList();

    return View(viewModel);
}

When they get to my view they are populated with the DB records (great). I then pass the model to the partial view which displays these lists as checkboxes, ready for user manipulation (I have tried based on another suggestion using for loop instead of foreach loop, made no difference):

@model LanguageSchoolsUK.Models.RegisterModel

@foreach (var item in Model.Facilities)
{
    @Html.Label(item.name);
    @Html.CheckBox(item.name, false, new { id = item.facility_id, @class = "RightSpacing", @description = item.description }) 
}

When I submit the form and it ends up back at my controller this time calling the overloaded register function on the controller:

[HttpPost]
public ActionResult Register(RegisterModel model)
{
    if (ModelState.IsValid)
    {
        // Do stuff
    }

    return View(model); 
}

The problem is that the model parameter containing the lists (Facilities and Accreditations) is telling me that the lists are null.

Please can somebody tell me what I am doing wrong, why aren’t they populated with the collections that I originally passed through and hopefully a way of asking whick ones have been checked?

Thanks.

Answer 1

I have tried based on another suggestion using for loop instead of
foreach loop, made no difference

Try again, I am sure you will have more luck this time. Oh and use strongly typed helpers:

@model LanguageSchoolsUK.Models.RegisterModel
@for (var i = 0; i < Model.Facilities.Count; i++)
{
    @Html.HiddenFor(x => x.Facilities[i].name)
    @Html.LabelFor(x => x.Facilities[i].IsChecked, Model.Facilities[i].name);
    @Html.CheckBoxFor(
        x => x.Facilities[i].IsChecked, 
        new { 
            id = item.facility_id, 
            @class = "RightSpacing", 
            description = item.description // <!-- HUH, description attribute????
        }
    ) 
}

Also you will undoubtedly notice from my answer that checkboxes work with boolean fields on your model, not integers, not decimals, not strings => BOOLEANS.

So make sure that you have a boolean field on your model which will hold the state of the checkbox. In my example this field is called IsChecked but obviously you could feel absolutely free to find it a better name.