Unable to populate checkbox from database data in mvc 4

Question

This is my Controller code.

public ActionResult Create()
{
    ViewBag.grp_id = new SelectList(db.tm_grp_group, "grp_id", "grp_name");
    ViewBag.perm_id = new SelectList(db.tm_perm_level, "perm_id", "perm_levelname");
    return View();
}

Below is my view code.

@model Permission.ts_grp_perm_mapping
....
@using (Html.BeginForm()) {
    @Html.AntiForgeryToken()
    @Html.ValidationSummary(true)
    <fieldset>
        <legend>ts_grp_perm_mapping</legend>
        <div class="editor-label">
            @Html.LabelFor(model => model.grp_permid)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.grp_permid)
            @Html.ValidationMessageFor(model => model.grp_permid)
        </div>
        <div class="editor-label">
            @Html.LabelFor(model => model.grp_id, "tm_grp_group")
        </div>
        <div class="editor-field">
            @Html.DropDownList("grp_id", String.Empty)
            @Html.ValidationMessageFor(model => model.grp_id)
        </div>
        <div class="editor-label">
            @Html.LabelFor(model => model.perm_id, "tm_perm_level")
        </div>
        <div class="editor-field">
            @Html.DropDownList("perm_id", String.Empty)
            @Html.ValidationMessageFor(model => model.perm_id)
        </div>
        <p>
            <input type="submit" value="Create" />
        </p>
    </fieldset>
}

In controller ViewBag.perm_id contains some values (this is foreign key). In view perm.id displays in the form of dropdownbox but I want it in the form of checkboxlist. How can I achieve this?

This is the viewmodel I created.

public class AssignUserViewModel
{
    public tm_perm_level[] perms { get; set; }
    public int grp_id { get; set; }
}

Now in controller how can i send values to view? This is my tm_perm_level model

public partial class tm_perm_level
{
    public tm_perm_level()
    {
        this.ts_grp_perm_mapping = new HashSet<ts_grp_perm_mapping>();
    }
    public int perm_id { get; set; }
    public string perm_levelname { get; set; }
    public string perm_description { get; set; }
    public bool perm_status { get; set; }
    public virtual ICollection<ts_grp_perm_mapping> ts_grp_perm_mapping { get; set; }
}

This is ts_grp_perm_mapping model

public partial class ts_grp_perm_mapping
{
    public ts_grp_perm_mapping()
    {
        this.ts_perm_levelmapping = new HashSet<ts_perm_levelmapping>();
    }
    public int grp_permid { get; set; }
    public int grp_id { get; set; }
    public int perm_id { get; set; }
    public List<tm_perm_level> permissions { get; set; }

    public virtual tm_grp_group tm_grp_group { get; set; }
    public virtual tm_perm_level tm_perm_level { get; set; }
    public virtual ICollection<ts_perm_levelmapping> ts_perm_levelmapping { get; set; }
}

Answer 1

Especially when editing, always start with view models to represent what you want to display (refer What is ViewModel in MVC?)

public class PermissionVM
{
  public int ID { get; set; }
  public string Name { get; set; }
  public bool IsSelected { get; set; }
}
public class GroupPermissionVM
{
  public int GroupID { get; set; }
  public IEnumerable<SelectListItem> GroupList { get; set; }
  public IEnumerable<PermissionVM> Permissions { get; set; }
}

Then create an EditorTemplate for PermissionVM. In the /Views/Shared/EditorTemplates/PermissionVM.cshtml folder

@model PermissionVM
<div>
    @Html.HiddenFor(m => m.ID)
    @Html.HiddenFor(m => m.Name)
    @Html.CheckBoxFor(m => m.IsSelected)
    @Html.LabelFor(m => m.IsSelected, Model.Name)
</div>

and the main view will be

@model GroupPermissionVM
....
@using (Html.BeginForm())
{
    // dropdownlist
    @Html.LabelFor(m => m.GroupID)
    @Html.DropDownListFor(m => m.GroupID, Model.GroupList, "Please select")
    @Html.ValidationMessageFor(m => m.GroupID)
    // checkboxlist
    @Html.EditorFor(m => m.Permissions)

    <input type="submit" value="Create" />
}

The controller methods would then be

public ActionResult Create()
{
    var groups = db.tm_grp_group;
    var permissions = db.tm_perm_level;

    GroupPermissionVM model = new GroupPermissionVM
    {
        GroupList = new SelectList(groups, "grp_id", "grp_name"),
        Permissions = permissions.Select(p => new PermissionVM
        {
            ID = p.perm_id,
            Name = p.perm_levelname
        }
    };
    return View(model);
}

[HttpPost]
public ActionResult Create(GroupPermissionVM model)
{
    if (!ModelState.IsValid)
    {
        var groups = db.tm_grp_group;
        model.GroupList = new SelectList(groups, "grp_id", "grp_name");
        return View(model);
    }
    // map the view model to a new instance of your data model(s)
    // note: to get the ID's of the selected permissions - 
    //    var selectedPermissions = model.Permissions.Where(p => p.IsSelected).Select(p => p.ID);
    // save and redirect
}

Side note: I strongly recommend you follow normal naming conventions

Edit

Based on OP's comment for an option using radio buttons to select only one item, the revised code would be

public class PermissionVM
{
  public int ID { get; set; }
  public string Name { get; set; }
}
public class GroupPermissionVM
{
  public int GroupID { get; set; }
  public int PermissionID { get; set; }
  public IEnumerable<SelectListItem> GroupList { get; set; }
  public IEnumerable<PermissionVM> Permissions { get; set; }
}

and the view would be (no separate EditorTemplate required)

@model GroupPermissionVM
....
@using (Html.BeginForm())
{
    // dropdownlist as above

    // radio buttons
    foreach (var permission in Model.Permissions)
    {
        <label>
            @Html.RadioButtonForm(m => m.PermissionID, permission.ID)
            <span>@permission.Name</span>
        </label>
    }
    <input type="submit" value="Create" />
}

and in the POST method, the value of model.PermissionID will contain the ID of the selected Permission.