Question

控制器 -

namespace TaskList.Controllers
{
  public class HomeController : Controller
  {
     //
     // GET: /Home/
     private TaskListDataContext  DB = new TaskListDataContext();

     //Task tasks = new Task();
     //Display a list of Tasks
     public ActionResult Index()
     {
        var tasks = from t in DB.Tasks
                    orderby t.EntryDate descending
                    select new TaskList.Models.Task()
                    {
                       Id = t.Id,
                       Task1 = t.Task1,
                       IsCompleted = t.IsCompleted,
                       EntryDate = t.EntryDate
                    };
        return View(tasks);
      }

      //Display a form for creating a new Task
      public ActionResult Create()
      {
         return View();
      }

      //Adding a new task to the database
      public ActionResult CreateNew(string tasktext)
      {
         //Add the new task to the database 
         Task newTask = new Task();
         newTask.Task1 = tasktext;
         newTask.IsCompleted = false;
         newTask.EntryDate = DateTime.Now;       
         DB.Tasks.InsertOnSubmit(newTask);
         DB.SubmitChanges();       
         return RedirectToAction("Index");
      }

      //Mark a task as complete
      public ActionResult Complete()
      {
         //Database Logic
         return RedirectToAction("Index");
      }
   }
}

查看：

<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<IEnumerable<TaskList.Models.Task>>"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title></title>
</head>
<body>
    <div>    
        <h1>My Tasks</h1>  
        <ul>
        <% foreach (TaskList.Models.Task task in ViewData.Model)
           {%>              
             <li>  
             <%  task.Task1.ToString(); %>
             </li>       
        <% } %>
        </ul>    
        <br /> <br />
        <a href='<%=Url.Action("Create")%>/filename'>Add my Tasks</a>
    </div>
</body>
</html>

模型是使用Linq Class -

制作的

[global::System.Data.Linq.Mapping.TableAttribute(Name="dbo.Tasks")]
public partial class Task : INotifyPropertyChanging, INotifyPropertyChanged
{
   private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);       
   private int _Id;         
   private string _Task1;           
   private bool _IsCompleted;       
   private System.DateTime _EntryDate;      
}

当我尝试运行应用程序时，它显示错误

“在查询中显式构造实体类型'TaskList.Models.Task' 是不允许的。“

在foreach循环视图中。

实际上我正试图在这里创建一个用VB构建的应用程序的C＃veriosn。

http://www.asp.net/mvc/videos/mvc-2/how-do-i/creating-a-tasklist-application-with-aspnet-mvc

Answer 1

您可能需要转换为列表，如

var tasks = (from t in DB.Tasks orderby t.EntryDate descending select new TaskList.Models.Task() { Id = t.Id, Task1 = t.Task1, IsCompleted = t.IsCompleted, EntryDate = t.EntryDate }).ToList();

Answer 2

如错误消息所示，您无法在查询语句中创建映射实体。您可以选择现有实体：

var tasks = from t in DB.Tasks
            orderby t.EntryDate descending
            select t;

，或创建查询之外的新实体列表：

var taskEntities = from t in DB.Tasks
                    orderby t.EntryDate descending
                    select t;
var tasks = new List<TaskList.Models.Task>();
foreach(var taskEntity in taskEntities)
{
    tasks.Add(new TaskList.Models.Task()
                {
                   Id = taskEntity.Id,
                   Task1 = taskEntity.Task1,
                   IsCompleted = taskEntity.IsCompleted,
                   EntryDate = taskEntity.EntryDate
                });
}
return View(tasks);

，取决于您的要求。

ASP.NET MVC2应用程序在视图中显示错误

2 个答案: