My list will be empty when POST the form - asp.net-mvc-4

Question

I have some problem with the MVC, I'll try to describe. I have 2 class in my model.
public class ApplicationPermissionVM
{
public ApplicationPermission Permission { get; set; }
public bool IsSelected { get; set; }
}
public class RoleAndPermissonsModel
{
//Constructor skipped
public ApplicationRole ApplicationRole { get; set; }
public IEnumerable<ApplicationPermissionVM> Permissions { get; set; }
}
The second model is the main model, and I initialize the model in controller. The ApplicationRole is null and I have got 19 element in the list. When I POST the form the ApplicationRole member will be created, but the Permissions list will be empty so will lost all selection. If anyone knows what is the problem please write to me.
Controller:
[HttpGet]
public ActionResult NewRole()
{
_model = new RoleAndPermissonsModel();
return View(_model);
}
[HttpPost]
public ActionResult NewRole(RoleAndPermissonsModel newRole)
{
if (ModelState.IsValid)
{
var id = _applicationRoleService.AddNewRole(newRole.ApplicationRole);
_applicationRoleService.AssignPermissionsToRole(newRole.SelectedItems, id);
}
return RedirectToAction("Index");
}
View:
#model EO.Core.WebUI.Models.RoleAndPermissonsModel
#using (Html.BeginForm("NewRole", "PermissionRole", FormMethod.Post, new { id = "frmNewRole" }))
{
#Html.AntiForgeryToken()
#Html.ValidationSummary(true)
<fieldset>
<legend>ApplicationRole</legend>
<div class="editor-label">
#Html.LabelFor(model => model.ApplicationRole.Name)
</div>
<div class="editor-field">
#Html.EditorFor(model => model.ApplicationRole.Name)
#Html.ValidationMessageFor(model => model.ApplicationRole.Name)
</div>
<table>
<tr>
<th>
#Html.DisplayNameFor(model => model.IsSelected)
</th>
<th></th>
</tr>
#foreach (var item in Model.Permissions)
{
<tr>
<td>
#Html.EditorFor(modelItem => item.IsSelected)
</td>
<td>
#Html.DisplayFor(modelItem => item.Permission.Name);
</td>
</tr>
}
</table>
<p>
<input type="submit" value="Save" />
</p>
</fieldset>
}

Answer 1

you need manually to loop through the list and output it like
<input type="text"
id="Permissions[0].IsSelected"
name="Permissions[0].IsSelected" value="" />
so, change your code to:
#for(int i = 0; i < Model.Permissions.Count; i++)
{
<tr>
<td><input type="checkbox"
id="Permissions[#(i)].IsSelected"
name="Permissions[#(i)].IsSelected" /></td>
<td><input type="text"
id="Permissions[#(i)].Permission.Name"
name="Permissions[#(i)].Permission.Name" /></td>
</tr>
}
because you have an object inside your type Permissions remember to initialiate it or you will get a null reference.
public class RoleAndPermissonsModel
{
public RoleAndPermissonsModel() {
this.Permissions = new List<ApplicationPermissionVM>();
}
public ApplicationRole ApplicationRole { get; set; }
public IEnumerable<ApplicationPermissionVM> Permissions { get; set; }
}
or you can easily create a ViewModel instead and use that to interlink your Model to your View.
Note: I do wonder, if your list is always null (as you are passing an empty/null list) why are you looping through Model.Permissions ?
In order to do the "EDIT" view, the loop code should be:
#for(int i = 0; i < Model.Permissions.Count; i++)
{
<tr>
<td><input type="checkbox"
#(Permissions[i].IsSelected ? "checked='checked'" : "")
id="Permissions[#(i)].IsSelected"
name="Permissions[#(i)].IsSelected" /></td>
<td><input type="text"
id="Permissions[#(i)].Permission.Name"
name="Permissions[#(i)].Permission.Name"
value="#(Permissions[i].Permission.Name)" /></td>
</tr>
}
all you need to add is checked to the checkbox if it's selected and fill the permission name to the other input.