ViewModel分配了一個對象，我怎樣才能將它傳回到Post？

Question

所以，我有兩種方法：

public ActionResult Create(Guid id) 
    { 
     Assignment viewModel = new Assignment(); 
     viewModel.Classroom = classroomRepository.GetByID(id); 
     return View(viewModel); 
    } 

    [HttpPost] 
    public ActionResult Create(Assignment assignment) 
    { 
     if (ModelState.IsValid) 
     { 
      assignmentRepository.Insert(assignment); 
      assignmentRepository.Save(); 
      return RedirectToAction("Index"); 
     } 
     return View(assignment); 
    } 

正如你可以看到，當我加載了我創建頁面，我加載一個教室到視圖模型。這將工作並在視圖上顯示正確的課堂。

當我POST到Create方法時，我的問題發生了，我的assignment對象現在不包含（它是NULL）我在GET中傳入的課堂。

編輯〜要顯示視圖：

@model My_School_Book.Models.Assignment 
@{ 
    ViewBag.Title = "Create"; 
} 
<div class="span9"> 
    <div class="row-fluid"> 
     <h1>Creating New Assignment:</h1> 
     <hr /> 
     @using (Html.BeginForm("Create", "Assignment", FormMethod.Post, new { @class = "form-horizontal" })) 
     { 
      @Html.ValidationSummary(true) 

      <div class="control-group"> 
       @Html.LabelFor(model => model.Classroom.Name, "Classroom", new { @class = "control-label" }) 
       <div class="controls"> 
        <span style="font-size: 26px;">@Html.DisplayTextFor(model => model.Classroom.Name)</span> 
       </div> 
      </div> 

      <div class="control-group"> 
       @Html.LabelFor(model => model.Name, new { @class = "control-label" }) 
       <div class="controls"> 
        @Html.TextBoxFor(model => model.Name) 
        @Html.ValidationMessageFor(model => model.Name) 
       </div> 
      </div> 

      <div class="control-group"> 
       @Html.LabelFor(model => model.Description, new { @class = "control-label" }) 
       <div class="controls"> 
        @Html.TextAreaFor(model => model.Description) 
        @Html.ValidationMessageFor(model => model.Description) 
       </div> 
      </div> 

      <div class="control-group"> 
       @Html.LabelFor(model => model.AssignedDate, new { @class = "control-label" }) 
       <div class="controls"> 
        <div class="input-prepend"> 
         <span class="add-on"><i class="icon-calendar"></i></span>@Html.TextBoxFor(model => model.AssignedDate) 
        </div> 
        @Html.ValidationMessageFor(model => model.AssignedDate) 
       </div> 
      </div> 

      <div class="control-group"> 
       @Html.LabelFor(model => model.DueDate, new { @class = "control-label" }) 
       <div class="controls"> 
        <div class="input-prepend"> 
         <span class="add-on"><i class="icon-calendar"></i></span>@Html.TextBoxFor(model => model.DueDate) 
        </div> 
        @Html.ValidationMessageFor(model => model.DueDate) 
       </div> 
      </div> 

      <div class="control-group"> 
       @Html.LabelFor(model => model.Weight, new { @class = "control-label" }) 
       <div class="controls"> 
        @Html.TextBoxFor(model => model.Weight, new { @class = "span2" }) 
        @Html.ValidationMessageFor(model => model.Weight) 
       </div> 
      </div> 

      <div class="control-group"> 
       @Html.LabelFor(model => model.Total, new { @class = "control-label" }) 
       <div class="controls"> 
        @Html.TextBoxFor(model => model.Total, new { @class = "span2" }) 
        @Html.ValidationMessageFor(model => model.Total) 
       </div> 
      </div> 

      <div class="form-actions"> 
       <button type="submit" class="btn btn-primary"><i class="icon-plus-6"></i>&nbsp;Create</button> 
       <a href="@Url.Action("Index", "Assignment")" class="btn btn-primary"><i class="icon-back"></i>&nbsp;Cancel</a> 
      </div> 
     } 
    </div> 
</div> 
@section Scripts 
{ 
    <script type="text/javascript"> 
     $(function() { 
      $("#AssignedDate").datepicker({ 
       showOtherMonths: true, 
       selectOtherMonths: true, 
       dateFormat: "DD MM d, yy", 
       minDate: -14, 
       onSelect: function (selectedDate) { 
        $("#DueDate").datepicker("option", "minDate", selectedDate); 
       } 
      }); 
      $("#DueDate").datepicker({ 
       dateFormat: "DD MM d, yy", 
       minDate: 0, 
       onSelect: function (selectedDate) { 
        $("#AssignedDate").datepicker("option", "maxDate", selectedDate); 
       } 
      }); 
     }); 
    </script> 
} 

Answer 1

我結束了使用視圖模型：

public class AssignmentCreateData 
{ 
    public Guid ClassroomID { get; set; } 
    public String ClassroomName { get; set; } 
    public Assignment Assignment { get; set; } 
} 

和我的控制器是這樣的：

public ActionResult Create(Guid id) 
    { 
     AssignmentCreateData viewModel = new AssignmentCreateData(); 
     Classroom classroom = classroomRepository.GetByID(id); 
     viewModel.ClassroomID = classroom.ClassroomID; 
     viewModel.ClassroomName = classroom.Name; 
     viewModel.Assignment = null; 
     return View(viewModel); 
    } 

    [HttpPost] 
    public ActionResult Create(AssignmentCreateData viewModel) 
    { 
     if (ModelState.IsValid) 
     { 
      viewModel.Assignment.ClassroomID = viewModel.ClassroomID; 
      assignmentRepository.Insert(viewModel.Assignment); 
      assignmentRepository.Save(); 
      return RedirectToAction("Index"); 
     } 
     return View(viewModel); 
    } 

然後我的視圖包括：

@Html.HiddenFor(model => model.ClassroomID) 

Answer 2

你只包括Classroom.Name，從而對錶單提交無所不有該模型用粘結劑來填充你的模型。

你真的需要回教室嗎？你想達到什麼目的？ 如果你需要的只是ID寫出來的：

@Html.HiddenFor(o=>o.Classroom.ClassroomId)

（或任何ID爲），並加載備份在服務器端。

如果你真的需要它 - 你可以通過它

@Html.EditorFor(o=>o.Classroom)

寫出來作爲輸入，然後允許最終用戶修改它，我不認爲你想要的，所以我會使用的ID（ GUID）。

Answer 3

如果希望課堂生存後，那麼你需要將它添加到形成hiddenfield：

只需添加到這個形式：

@Html.HiddenFor(m=m.Classroom.ClassroomId) 
@Html.HiddenFor(m=m.Classroom.ClassroomName)