在DropDownListFor（）中顯示類型而不是數據

Question

嘗試用ViewModel填充用戶和角色，但它顯示類型而不是數據，如System.Data.Entity.DynamicProxies.AppUser.xxx（用於用戶）和System.Data。 Entity.DynamicProxies.IdentityRole.xxx（用於角色）。

代碼如下。

public class AppUser : IdentityUser 
    { 
     //add custom properties which have not included in IdentityUser before 
     public string Designation { get; set; } 

     public async Task<ClaimsIdentity> GenerateUserIdentityAsync(UserManager<AppUser> manager) 
     { 
      // Note the authenticationType must match the one defined in CookieAuthenticationOptions.AuthenticationType 
      var userIdentity = await manager.CreateIdentityAsync(this, DefaultAuthenticationTypes.ApplicationCookie); 
      // Add custom user claims here 
      return userIdentity; 
     } 

     public static ERPContext Create() 
     { 
      return new ERPContext(); 
     } 
    } 



public class AppRole : IdentityRole 
    { 
     public AppRole() : base() { } 
     public AppRole(string name) : base(name) { } 
     // extra properties here 
     public string Description { get; set; } 
    } 

視圖模型

public class UserAssignRoleViewModel 
    { 

     public string Username { get; set; } 

     public string Role { get; set; } 
     [Required] 
     public List<AppUser> Users { get; set; } 
     [Required] 
     public List<IdentityRole> Roles { get; set; } 

     public int SelectedId { set; get; } 

     public int SelectedRoleId { set; get; } 
    } 

RoleController

public ActionResult ManageUserRoles() 
     { 
      //this code is also an alternate way to fetch the roles from Owin // Startup config 
      // var roles = HttpContext.GetOwinContext().GetUserManager<RoleManager<IdentityRole>>().Roles; 
      //var rolelist = context.Roles.OrderBy(r => r.Name).ToList().Select(rr => new SelectListItem { Value = rr.Name.ToString(), Text = rr.Name }).ToList(); 
      var model = new UserAssignRoleViewModel(); 
      var users = context.Users.ToList(); 
      users.Select(s => new SelectListItem 
      { 
       Value = s.Id.ToString(), 
       Text = s.UserName.ToString() 
      }); 
      var roles = context.Roles.ToList(); 
      roles.Select(s => new SelectListItem 
      { 
       Value = s.Id.ToString(), 
       Text = s.Name.ToString() 
      }); 
      ViewBag.Users = users; 
      //var list = context.Roles.OrderBy(r => r.Name).ToList().Select(rr => new SelectListItem { Value = rr.Name.ToString(), Text = rr.Name }).ToList(); 
      //ViewBag.Roles = list; 
      model.Users = users; 
      model.Roles = roles; 
      return View(model); 
     } 

     [HttpPost] 
     [ValidateAntiForgeryToken] 
     public ActionResult RoleAddToUser(string UserName, string RoleName) 
     { 
      AppUser user = context.Users.Where(u => u.UserName.Equals(UserName, StringComparison.CurrentCultureIgnoreCase)).FirstOrDefault(); 
      var userManager = new UserManager<AppUser>(new UserStore<AppUser>(context)); 

      userManager.AddToRole(user.Id, RoleName); 

      ViewBag.ResultMessage = "Role Assigned successfully !"; 

      // prepopulat users for the view dropdown 
      var _users = context.Users.OrderBy(r => r.UserName).ToList().Select(rr => new SelectListItem { Value = rr.UserName.ToString(), Text = rr.UserName }).ToList(); 
      ViewBag.Users = _users; 
      // prepopulat roles for the view dropdown 
      var _roles = context.Roles.OrderBy(r => r.Name).ToList().Select(rr => new SelectListItem { Value = rr.Name.ToString(), Text = rr.Name }).ToList(); 
      ViewBag.Roles = _roles; 

      return View("ManageUserRoles"); 
     } 

     [HttpPost] 
     [ValidateAntiForgeryToken] 
     public ActionResult GetRoles(string UserName) 
     { 
      if (!string.IsNullOrWhiteSpace(UserName)) 
      { 
       AppUser user = context.Users.Where(u => u.UserName.Equals(UserName, StringComparison.CurrentCultureIgnoreCase)).FirstOrDefault(); 
       var userManager = new UserManager<AppUser>(new UserStore<AppUser>(context)); 

       ViewBag.RolesForThisUser = userManager.GetRoles(user.Id); 


       // prepopulat roles for the view dropdown 
       var list = context.Roles.OrderBy(r => r.Name).ToList().Select(rr => new SelectListItem { Value = rr.Name.ToString(), Text = rr.Name }).ToList(); 
       ViewBag.Roles = list; 
       // prepopulat roles for the view dropdown 
       var users = context.Users.OrderBy(r => r.UserName).ToList().Select(rr => new SelectListItem { Value = rr.UserName.ToString(), Text = rr.UserName }).ToList(); 
       ViewBag.Users = users; 
      } 

      return View("ManageUserRoles"); 
     } 

上面的代碼我剛纔試過幾個評論代碼。

最後，觀點如下

@model ERPLite.Models.UserAssignRoleViewModel 
@{ 
    ViewBag.Title = "ManageUserRoles"; 

} 

@Html.ActionLink("Create New Role", "Create") | @Html.ActionLink("Manage User Role", "ManageUserRoles") 
<hr /> 


@using (Html.BeginForm("RoleAddToUser", "Role")) 
{ 
    @Html.AntiForgeryToken() 
    @Html.ValidationSummary(true) 


    <p> 

     User Name: @Html.DropDownListFor(x => x.SelectedId, new SelectList(Model.Users), "Select") 
     @*Role Name: @Html.DropDownList("RoleName", (IEnumerable<SelectListItem>)ViewBag.Roles, "Select ...")*@ 
     Role Name: @Html.DropDownListFor(u => u.SelectedRoleId, new SelectList(Model.Roles), "Select ...") 
    </p> 

    <input type="submit" value="Save" /> 
} 
<hr /> 
<h3>Get Roles for a User</h3> 
@using (Html.BeginForm("GetRoles", "Role")) 
{ 
    @Html.AntiForgeryToken() 
    <p> 
     Username : @Html.TextBox("UserName") 
     <input type="submit" value="Get Roles for this User" /> 
    </p> 
} 

@if (ViewBag.RolesForThisUser != null) 
{ 
    <div style="background-color:yellow;"> 
     <h3>Roles for this user </h3> 
     <ol> 
      @foreach (string s in ViewBag.RolesForThisUser) 
      { 
       <li>@s</li> 
      } 
     </ol> 
    </div> 
} 

當我使用ViewBag它完美的作品，除了驗證爲theDropdowns（需要確認）無法實現，因此與所需的註釋和視圖模型通過視圖模型被在這種情況下推薦的方式。 感謝任何幫助。提前致謝 。 使用MVC 5，帶有標識的CodeFirst EF。

Answer 1

您在視圖模型中使用的是您的身份模型而不是SelectListItem。

在您的視圖模型變化

[Required] 
    public List<AppUser> Users { get; set; } 
    [Required] 
    public List<IdentityRole> Roles { get; set; } 

到

public List<SelectListItem> Users { get; set; } 
    public List<SelectListItem> Roles { get; set; } 

和Required屬性添加到SelectedId和SelectedRoleId。

在你ManageUserRoles操作您的視圖模型的人口變化對

 model.Users = users.Select(s => new SelectListItem 
     { 
      Value = s.Id.ToString(), 
      Text = s.UserName.ToString() 
     }); 
     var roles = context.Roles.ToList(); 
     model.Roles = roles.Select(s => new SelectListItem 
     { 
      Value = s.Id.ToString(), 
      Text = s.Name.ToString() 
     }); 

順便說一句，使用Select()這樣

var roles = context.Roles.ToList(); 
     roles.Select(s => new SelectListItem 
     { 
      Value = s.Id.ToString(), 
      Text = s.Name.ToString() 
     }); 

什麼都不做。您必須將Select的結果分配給一個變量。