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StudentModel。複選框列表 - 在發佈：創建 - NullReferenceException
namespace mvcApp.Models
{
public class StudentModel
{
[Display(Name = "First Name")]
public string FirstName { get; set; }
[Display(Name = "Last Name")]
public string LastName { get; set; }
[Display(Name = "Email Address")]
public string EmailAddress { get; set; }
public List<SchoolOrganization> Organizations { get; set; }
}
public class SchoolOrganization
{
public string Name { get; set; }
public bool IsInvolved { get; set; }
}
}
學生涉及多個組織。
控制器
namespace mvcApp.Controllers
{
public class HomeController : Controller
{
public ActionResult Index()
{
ViewBag.Message = "Modify this template to jump-start your ASP.NET MVC application.";
return View();
}
public ActionResult StudentInformation()
{
// populate student with data
var student = new StudentModel() { FirstName = "Joe", LastName = "Doe", EmailAddress = "[email protected]"};
// Populate with Organizations
student.Organizations = new List<SchoolOrganization>();
student.Organizations.Add(new SchoolOrganization() { Name = "Math Club", IsInvolved = true});
student.Organizations.Add(new SchoolOrganization() { Name = "Chess Club", IsInvolved = false });
student.Organizations.Add(new SchoolOrganization() { Name = "Football", IsInvolved = true });
return View(student);
}
**[HttpPost]
public ActionResult StudentInformation(StudentModel student)
{
Response.Write("Name: " + student.FirstName);
foreach (var o in student.Organizations)
{
Response.Write(o.Name + " : " + o.IsInvolved.ToString());
}
return View();
}**
}
}
數據將從數據庫中最終填充。
查看
@model mvcApp.Models.StudentModel
@{
ViewBag.Title = "StudentInformation";
}
<h2>StudentInformation</h2>
@using (Html.BeginForm()) {
@Html.AntiForgeryToken()
@Html.ValidationSummary(true)
<fieldset>
<legend>StudentModel</legend>
<div class="editor-label">
@Html.LabelFor(model => model.FirstName)
</div>
<div class="editor-field">
@Html.EditorFor(model => model.FirstName)
@Html.ValidationMessageFor(model => model.FirstName)
</div>
<div class="editor-label">
@Html.LabelFor(model => model.LastName)
</div>
<div class="editor-field">
@Html.EditorFor(model => model.LastName)
@Html.ValidationMessageFor(model => model.LastName)
</div>
<div class="editor-label">
@Html.LabelFor(model => model.EmailAddress)
</div>
<div class="editor-field">
@Html.EditorFor(model => model.EmailAddress)
@Html.ValidationMessageFor(model => model.EmailAddress)
</div>
<div>
<table>
<tr>
<td>Organization Name</td><td>Is Involved</td>
</tr>
@for (int i = 0; i < Model.Organizations.Count; i++) <== System.NullReferenceException here
{
@Html.HiddenFor(m => m.Organizations[i].IsInvolved)
<tr>
<td>@Html.DisplayFor(m => m.Organizations[i].Name)</td>
<td>@Html.CheckBoxFor(m => m.Organizations[i].IsInvolved)</td>
</tr>
}
</table>
</div>
<p>
<input type="submit" value="Save" />
</p>
</fieldset>
}
上述代碼顯示細跟HttGet。但是，當我嘗試更新我得到System.NullReferenceException。 https://www.dropbox.com/s/dz0bg3hkd0yq8e3/studentInformation.png?dl=0
任何人都可以請幫忙看看是怎麼回事？
謝謝。