为什么隐藏字段值在MVC中的表单提交时无法在控制器端正确显示？

Question

我使用了MVC 5和MongoDB，我试图在表单提交的控制器中获取隐藏字段值（ObjectId）但是获取默认值（000000000000000000000000）而不是实际值（5af58cedf86bc82ab0e0f825）。

此处字段类型为ObjectId（MongoDB.Bson Type）

请帮助我，我是MongoDB的新手。 在此先感谢

@using (Html.BeginForm()) {
<div class="container ">
  <div class="row">
    @Html.HiddenFor(m => m.Employee._id, new { @Value = ObjectId.Parse(Model.Employee._id.ToString()) });
    <div class="col-md-12">
      <h3 class="text-center" style="margin: 25px 0;">
        Employee Registration Form
      </h3>
      <h4 class="text-center" style="margin: 25px 0">
        <span style="color:red">
                            @if (TempData["ErrorMessage"] != null)
                            {
                                @TempData["ErrorMessage"]
                            }
                        </span>
        <span span style="color:forestgreen">
                            @if (TempData["SuccessMessage"] != null)
                            {
                                @TempData["SuccessMessage"]
                            }
                        </span>
      </h4>
      <div class="col-md-2 float-left"></div>
      <div class="col-md-8 float-left">
        <div class="form-group">
          <div class="row">
            <div class="col-md-6">
              <label>Employee First Name : </label> @Html.TextBoxFor(m => m.Employee.FirstName, new { @class = "form-control" })
            </div>
            <div class="col-md-6">
              <label>Employee Last Name : </label> @Html.TextBoxFor(m => m.Employee.LastName, new { @class = "form-control" })
            </div>
          </div>
        </div>
        <div class="form-group">
          <div class="row">
            <div class="col-md-6">
              <label>Employee Contact No : </label> @Html.TextBoxFor(m => m.Employee.ContactNumber, new { @class = "form-control" })
            </div>
            <div class="col-md-6">
              <label>Email Address : </label> @Html.TextBoxFor(m => m.Employee.Email, new { @class = "form-control" })
            </div>
          </div>
        </div>
        <div class="form-group">
          <div class="row">
            <div class="col-md-6">
              <label>Salary : </label> @Html.TextBoxFor(m => m.Employee.Salary, new { @class = "form-control" })
            </div>
            <div class="col-md-6">
              <label>Gender: </label>
              <div>
                Male @Html.RadioButtonFor(m => m.Employee.Gender, "Male") Female @Html.RadioButtonFor(m => m.Employee.Gender, "Female")
              </div>
            </div>
          </div>
        </div>
        <div class="form-group">
          <div class="row">
            <div class="col-md-6">
              <label>Designation: </label> @Html.TextBoxFor(m => m.Employee.Designation, new { @class = "form-control" })
            </div>
            <div class="col-md-6">
              <label>Address: </label> @Html.TextAreaFor(m => m.Employee.Address, new { @class = "form-control" })
            </div>
          </div>
        </div>

        <div class="form-group">
          <input type="submit" class="btn btn-default" value="Save Employee" />
          <input type="reset" class="btn btn-info" value="Cancel" />
        </div>

      </div>
      <div class="col-md-2 float-left"></div>
      <br />
      <br />
      <div class="col-md-12 float-left"></div>
      <div class="col-md-1 float-left"></div>
      <div class="col-md-10 float-left">
      </div>
      <div class="col-md-1 float-left"></div>
    </div>
  </div>
</div>
}