實體框架TryUpdateModel子對象？

Question

我知道你們大多數人會建議我應該使用特定於我使用的窗體的ViewModels，但我很好奇爲什麼我的子對象不能綁定到TryUpdateModel上。

@using (Html.BeginForm()) { 
    @Html.ValidationSummary(true) 
    <fieldset> 
     <legend>User</legend> 

     @Html.HiddenFor(model => model.UserId) 
    @Html.HiddenFor(model => model.PrimaryAddress.AddressId) 
    <div class="editor-label"> 
      @Html.LabelFor(model => model.PrimaryAddress.FirstName) 
     </div> 
     <div class="editor-field"> 
      @Html.EditorFor(model => model.PrimaryAddress.FirstName) 
      @Html.ValidationMessageFor(model => model.PrimaryAddress.FirstName) 
     </div> 

     <div class="editor-label"> 
      @Html.LabelFor(model => model.PrimaryAddress.LastName) 
     </div> 
     <div class="editor-field"> 
      @Html.EditorFor(model => model.PrimaryAddress.LastName) 
      @Html.ValidationMessageFor(model => model.PrimaryAddress.LastName) 
     </div> 

     <div class="editor-label"> 
      @Html.LabelFor(model => model.UserName) 
     </div> 
     <div class="editor-field"> 
      @Html.EditorFor(model => model.UserName) 
      @Html.ValidationMessageFor(model => model.UserName) 
     </div> 

     <div class="editor-label"> 
      @Html.LabelFor(model => model.Email) 
     </div> 
     <div class="editor-field"> 
      @Html.EditorFor(model => model.Email) 
      @Html.ValidationMessageFor(model => model.Email) 
     </div> 

     <div class="editor-label"> 
      @Html.LabelFor(model => model.IsApproved) 
     </div> 
     <div class="editor-field"> 
      @Html.EditorFor(model => model.IsApproved) 
      @Html.ValidationMessageFor(model => model.IsApproved) 
     </div> 

     <div class="editor-label"> 
      @Html.LabelFor(model => model.IsEmployee) 
     </div> 
     <div class="editor-field"> 
      @Html.EditorFor(model => model.IsEmployee) 
      @Html.ValidationMessageFor(model => model.IsEmployee) 
     </div> 

     <p> 
      <input type="submit" value="Save" /> 
     </p> 
    </fieldset> 
} 

而控制器代碼：

[HttpPost] 
public ActionResult Edit(int id, FormCollection form) 
{ 
    var user = Token.DB.Users.Include("PrimaryAddress").Single(x => x.UserId == id); 
    if (TryUpdateModel(user, new string[] { "UserName", "Email", "IsApproved", "IsEmployee", "PrimaryAddress.FirstName", "PrimaryAddress.LastName" })) 
    { 
     try 
     { 
      Token.DB.SaveChanges(); 
      return RedirectToAction("index"); 
     } 
     catch (Exception ex) 
     { 
      while (ex.InnerException != null) 
       ex = ex.InnerException; 
      if (ex.Message.ToLowerInvariant().Contains("unique")) 
       ModelState.AddModelError("UserName", "UserName already exists"); 
     } 
    } 
    return View(User); 
} 

代碼不拋出任何異常，它只是不填充表單中的user.PrimaryAddress.FirstName或user.PrimaryAddress.LastName。我想知道爲什麼？

我已經知道我可以用特定的ViewModel解決問題並在後臺映射信息。我也可以這樣做：

<!-- Edit.cshtml --> 
<div class="editor-field"> 
    @Html.EditorFor(model => model.PrimaryAddress.FirstName, null, "FirstName") 
    @Html.ValidationMessageFor(model => model.PrimaryAddress.FirstName) 
</div> 

<div class="editor-label"> 
    @Html.LabelFor(model => model.PrimaryAddress.LastName) 
</div> 
<div class="editor-field"> 
    @Html.EditorFor(model => model.PrimaryAddress.LastName, null, "LastName") 
    @Html.ValidationMessageFor(model => model.PrimaryAddress.LastName) 
</div> 

// UsersController.cs 
if (TryUpdateModel(user, new string[] { "UserName", "Email", "IsApproved", "IsEmployee"}) 
&& TryUpdateModel(user.PrimaryAddress, new string[] {"FirstName", "LastName" })) 

所以真正的問題是爲什麼它沒有在第一個例子中綁定？

Answer 1

所以真正的問題是爲什麼它沒有在第一個例子中綁定？

您的問題的答案非常簡單：UpdateModel，TryUpdateModel或[Bind]屬性都不支持包含/排除屬性列表中的「嵌套屬性」。因此，請妥善做好事情並使用視圖模型。防範大規模財產分配攻擊只是爲什麼您應該使用視圖模型的數百萬個原因之一。那麼，您似乎已經通過執行第二個TryUpdateModel找到了解決方法，但是如果您在此域對象上有很多屬性，那麼您的控制器操作代碼可能會很快變成意大利麪條管道代碼。

Answer 2

我發現一些情況下，我想做同樣的事情。我還發現子對象不起作用，但子對象的列表/集合確實很奇怪。

我找到了一個很好的link描述如何解決這個問題。

它結束了看起來像這樣：

[AcceptVerbs(HttpVerbs.Post)] 
public ActionResult Save(int id, FormCollection collection) 
{ 
    User user = null; 
    if (id == 0) 
    { 
     user = new User(); 
     UpdateModel(user, "User"); 
     user.Contact = new Contact(); 
     UpdateModel(user.Contact, "User.Contact"); 
     user.Contact.Addresses = new EntitySet<Address>(); 
     UpdateModel(user.Contact.Addresses, "User.Contact.Addresses"); 
    } 
    else 
    { 
     // get current user object from DB, however you normally do this is fine. 
     user = userRepository.GetById(id); 
     UpdateModel(user, "User"); 
     UpdateModel(user.Contact, "User.Contact"); 
     UpdateModel(user.Contact.Addresses, "User.Contact.Addresses"); 
    } 
    // at this point, model "user" and children would have been updated. 
} 
...