ModelState.IsValid在應該爲true時返回false

Question

我有一個非常簡單的MVC 2表單。它有兩個下拉菜單，用戶和角色。無論我選擇什麼，員工下拉菜單都會通過驗證，而角色下拉菜單則不會。雖然我打算實現一個選項，但沒有默認的「空白」選項，這就是爲什麼我需要驗證才能工作。它無法同時驗證客戶端和服務器。我只是不明白爲什麼一個人會工作，一個人不工作！

的形式爲：

<% using (Html.BeginForm()) {%> 

    <%:Html.ValidationSummary(true) %> 
    <%:Html.EditorFor(model => model.User, new { AllEmployees = Model.AllEmployees, RoleList = Model.RoleList })%> 

    <p> 
     <input type="submit" value="Add New User" /> 
    </p> 

    <% } %> 

<% Html.EndForm(); %> 

的編輯模板：

<tr> 
    <td> 
     <div class="editor-label"> 
      <%: Html.LabelFor(model => model.UserId) %> 
      <%: Html.RequiredMarkFor(model => model.UserId) %> 
     </div> 
    </td>  
    <td>  
    <div class="editor-field"> 
     <%: Html.DropDownListFor(model => model.UserId, new SelectList(ViewData["AllEmployees"] as IEnumerable, "UserId", "DisplayName", Model.UserId)) %> 
     <%: Html.ValidationMessageFor(model => model.UserId> 
    </div>  
    </td>  
</tr>  

<tr> 
    <td> 
     <div class="editor-label"> 
      <%: Html.LabelFor(model => model.AccessLevel)%> 
      <%: Html.RequiredMarkFor(model => model.AccessLevel)%> 
     </div> 
    </td>  
    <td>  
     <div class="editor-field"> 
      <%: Html.DropDownListFor(model => model.AccessLevel, new SelectList(ViewData["RoleList"] as IEnumerable, Model.AccessLevel))%> 
      <%: Html.ValidationMessageFor(model => model.AccessLevel)%> 
     </div>  
    </td>  
</tr> 

元數據：

[DisplayName("Employee")] 
    [Required(ErrorMessage = "Please select an employee.")] 
    [StringLength(8, ErrorMessage = "User Id must be less than 8 characters.")] 
    [DisplayFormat(ConvertEmptyStringToNull = false, 
          HtmlEncode = true)] 
    [DataType(DataType.Text)] 
    public object UserId { get; set; } 


    // Validation rules for Access Level 
    [DisplayName("Role")] 
    [Required(ErrorMessage = "Please select the role for this user.")] 
    [StringLength(15, ErrorMessage = "Role must be under 15 characters.")] 
    [DisplayFormat(ConvertEmptyStringToNull = false, 
          HtmlEncode = true)] 
    [DataType(DataType.Text)] 
    public object AccessLevel { get; set; } 

的獲取動作：

List<String> roles = (from o in txDB.Users 
             select o.AccessLevel).Distinct().ToList(); 

    var viewModel = new UserViewModel 
    { 
     User = new User(), 
     AllEmployees = empList, 
     RoleList = roles 
    }; 
    return View(viewModel); 

POST操作：

[HttpPost] 
    [AuthorizeAttribute(Roles="Administrator")] 
    public ActionResult Create(User user) 
    { 
     if(!ModelState.IsValid) 
     { 
      //ModelState is invalid 
      return View(new User()); 
     } 
     try 
     { 
      //do stuff 
     } 
    } 

所需的helper方法（從Define markup for [Required] fields in View in ASP.NET MVC 2.0）：

public static string RequiredMarkFor<TModel, TProperty>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TProperty>> expression) 
    { 
     if(ModelMetadata.FromLambdaExpression(expression, helper.ViewData).IsRequired) 
      return "*"; 
     else 
      return string.Empty; 
    } 

Answer 1

Post方法應該如下獲得服務器端驗證...

[HttpPost] 
[AuthorizeAttribute(Roles="Administrator")] 
public ActionResult Create(User user) 
{ 
    if(!TryUpdateModel(user)) 
    { 
     // Model is INVALID 
     return View(user); 
    } 
    else 
    { 
     // ModelState is VALID 
     // Do stuff 
    } 
} 

的else可能是多餘的取決於你在做什麼，但應該讓你去。 在上面的觀點你<% using Html.BeginForm() %>你需要

<% Html.EnableClientValidation(); %> 

您還需要參考腳本，MicrosoftAjax和MicrosoftMvcValidation我認爲

Answer 2

首先：你有兩個封閉的形式標記

如果使用

<% using (Html.BeginForm()) {%> 
<% } %> 

你不需要使用這個

<% Html.EndForm(); %> 

關於您正在使用的編輯器只爲您的用戶屬性，這是得到由模型綁定綁定

<%:Html.EditorFor(model => model.User, new { AllEmployees = Model.AllEmployees, RoleList = Model.RoleList })%> 

嘗試與EditorForModel來代替以前的代碼的唯一一個您的驗證問題因爲您的編輯器模板適用於模型類。

所以，你的表格應

<% using (Html.BeginForm()) {%> 

    <%:Html.ValidationSummary(true) %> 
    <table> 
     <%:Html.EditorForModel()%> 
    </table> 
    <p> 
     <input type="submit" value="Add New User" /> 
    </p> 
<% } %> 

改變，你就大功告成了！