部分视图返回Null模型ASP.NET MVC 4

Question

在我的MainView中，我能够使用_GetForTask局部视图渲染所有“TaskComment”（模型）。然后在我的_GetForTask局部视图中，我能够渲染_TaskCommentForm并成功传递了一个新的TaskComment模型实例。但是，每当我单击_TaskCommentForm局部视图中的“提交”按钮时，它总是返回null。我在这里错过了什么？非常感谢。

“TaskComment”模型

public partial class TaskComment
{
    public int TaskCommentID { get; set; }
    public Nullable<int> TaskID { get; set; }
    public Nullable<int> AuthorID { get; set; }
    public string Comment { get; set; }
    public Nullable<System.DateTime> TimeStamp { get; set; }

    public virtual Task Task { get; set; }
    public virtual Employee Employee { get; set; }
}

这是我的“MainView”

@Html.Action("_GetForTask", "TaskComment", new { TaskID = Model.TaskID })

_GetForTask PartialView

@model IEnumerable<ProjectYesha.Models.TaskComment>
<div id="comments">
    <ul>
        @foreach (var taskComment in Model)
        {
            <li>@taskComment.Comment</li>
        }
    </ul>  
    @using (Html.BeginForm("_Submit", "TaskComment", FormMethod.Post))
    { 
        @Html.AntiForgeryToken()
        @Html.Action("_TaskCommentForm", "TaskComment", new { TaskID = ViewBag.TaskID })
    }

</div> 

_TaskCommentForm PartialView

@model ProjectYesha.Models.TaskComment

@Html.HiddenFor(m=> m.TaskCommentID)
@Html.HiddenFor(m=> m.TaskID)
@Html.HiddenFor(m=> m.AuthorID)
@Html.HiddenFor(m=> m.TimeStamp)

@Html.HiddenFor(m=> m.Employee)
@Html.HiddenFor(m=> m.Task)
<div>   
    @using (Html.BeginForm())
    { 
        @Html.EditorFor(m => m.TaskID)
        @Html.EditorFor(m => m.Comment)
        <input type="submit" value = "Submit" />
    }
</div>

TaskCommentController

 public PartialViewResult _GetForTask(Int32 taskID)
        {
            ViewBag.TaskID = taskID;
            List<TaskComment> comments = db.TaskComments.Where(c => c.TaskID == taskID).ToList();
            return PartialView("_GetForTask", comments);
        }

        [ChildActionOnly()]
        public PartialViewResult _TaskCommentForm(Int32 taskID)
        {

            TaskComment comment = new TaskComment() 
            {
                TaskID = taskID ,
            };
            return PartialView("_TaskCommentForm", comment);
        }

        [HttpPost]
        [ValidateAntiForgeryToken()]
        public PartialViewResult _Submit(TaskComment comment)
        {
            db.TaskComments.Add(comment);
            db.SaveChanges();

            List<TaskComment> comments = db.TaskComments.Where(c => c.TaskID == comment.TaskID).ToList();
            ViewBag.TaskID = comment.TaskID;

            return PartialView("_GetForTask", comments);
        }