ASP MVC BindingModel中的一个对象从窗体到控制器为空

Question

我有绑定模型：

public class CreateBindingModel
{
    public object1 object1 { get; set; }

    public object2 object2 { get; set; }
}

我想通过控制器中的Create形式传递它：

    public ActionResult Create()
    {
        this.ViewBag.TaskId = new SelectList(this.db.Tasks, "Id", "Name");

        return this.View();
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Create(CreateBindingModel createBindingModel)
    {
        //body
    }

我的Create.cshtml如下：

@model namespace.Models.CreateBindingModel

@using (Html.BeginForm()) 
{
    @Html.AntiForgeryToken()
    
<div class="form-horizontal">

    <h4>Object1</h4>


    @Html.ValidationSummary(true, "", new { @class = "text-danger" })
    <div class="form-group">
        @Html.LabelFor(model => model.object1.FirstName, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.object1.FirstName, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.object1.FirstName, "", new { @class = "text-danger" })
        </div>
    </div>

    

    <h4>Object 2</h4>


    <div class="form-group">
        @Html.LabelFor(model => model.object2.TaskId, "TaskId", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownList("TaskId", null, htmlAttributes: new { @class = "form-control" })
            @Html.ValidationMessageFor(model => model.object2.TaskId, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.object2.DaysToExpire, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.object2.DaysToExpire, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.object2.DaysToExpire, "", new { @class = "text-danger" })
        </div>
    </div>


    <div class="form-group">
        <div class="col-md-offset-2 col-md-10">
            <input type="submit" value="Create" class="btn btn-default" />
        </div>
    </div>
</div>
}

我的问题是，为什么我可以从上面通过这种形式在DaysToExpire中获得object2，但是却无法从object2的下拉列表中获得TaskId（在{{1}中为null }控制器）？下拉列表会在我的表单中正确生成

Create的一部分效果很好

编辑

在object1类中创建属性时，

BindingModel

然后在public int TaskId { get; set; } 中重命名model.object2.TaskId并将其更改为@HTML，这样效果很好