在asp.net MVC中的多个下拉列表到actionresult

Question

I am using jquery choose multiple dropdownlist.

I have multiple values from selected dropdownlist.

Html:

    @using (Html.BeginForm()) {
    <div class="editor-field" style="width:150px;">

    @Html.DropDownList("UserRole", null, new { @class = "chosen-select",@multiple="multiple",@placeholder="Lütfen Rol Seçiniz",@style="width:250px;"})

    </div>

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

When i click to create button button submits to below actionresult

[HttpPost]
public ActionResult AddUser(List<UserRole> UserRole) 
{
return view();
}

UserRole is always null when i post it

UserRole Class properties below

public int UserRoleID { get; set; }
public Nullable<int> FirmUserID { get; set; }
public Nullable<int> RoleID { get; set; }

Where i miss how can i get selected all values in multiple dropdownlist ?

Any help will be appreciated.

Thanks.

Answer 1

在您的方案中，像这样添加列表框@Html.ListBox("UserRole", null, new { @class = "chosen-select",@multiple="multiple",@placeholder="Lütfen Rol Seçiniz",@style="width:250px;"})以便您找到结果。

Answer 2

You'll need to use a ListBox to get the behavior you desire, instead of a dropdown list. The ListBox can accept an array of selected roles, along with a MultiSelectList to display the selected items.

I would also recommend using a view model, instead of relying upon the ViewBag for handing your view state. See CloneMatching for the extension method.

    @model UserRoleViewModel
    ...
    <div>
        <div class="editor-label">
            User Roles<br />(Ctrl-click for multiple)
        </div>
        <div class="editor-field">
            @Html.ListBoxFor(model => model.SelectedRoles,new MultiSelectList(model.AvailableRoles,"Id","Description",Model.SelectedRoles))
        </div>        
    </div>

UserRoleViewModel:

 public class UserRoleViewModel {
     public User { get; set; }

     public List<int> SelectedRoles { get; set; }
     public List<Role> AvailableRoles { get; set; }
 }

UserRoleController:

 public ActionResult Edit(int id) {
     var user = MyDbContext.Users.Find(id);
     var model = new Model {
         User = user;
         SelectedRoles = user.UserRoles.Select(userRole => userRole.Role.Id).ToList();
         AvailableRoles = MyDb.Context.Roles.ToList();
     };
     return View(model);
 }

 [HttpPost]
 public ActionResult Edit(UserRoleViewModel model) {
     if (ModelState.IsValid) {
         var user = MyDbContext.Users.Find(id).CloneMatching(model.User);
         user.UserRoles.Clear();
         MyDbContext.SaveChanges();

         foreach( var roleId in model.SelectedRoles) {
             users.UserRoles.Add(new UserRole {
                 UserId = user.Id,
                 RoleId = roleId
             });
         }
         MyDbContext.SaveChanges();
         return RedirectToAction("Index");
     }        
     return View(model);
 }