Question

我的MVC项目有问题。尝试创建对象以将其添加到db时，它始终返回null。

public class ListsModel
{
    public EntitiesList EntityList { get; set; }
    public List<string> AllGroups { get; set; }
}

    public ActionResult Create()
    {
        ListsModel model = new ListsModel();
        model.EntityList = new EntitiesList();
        model.AllGroups = managerLists.GetAllListsKeys(); //For droplist

        return View(model);
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Create(ListsModel model)
    {
        if (ModelState.IsValid)
        {
            model.EntityList.List_CreatedTime = DateTime.Now;
            managerLists.AddNewObject(model.EntityList);
            return RedirectToAction("Index");
        }

        return View(model);
    }

一个简单的cshtml：

@using (Html.BeginForm())
{
    @Html.AntiForgeryToken()
    @Html.ValidationSummary(true)

    <fieldset>
        <legend>EntitiesList</legend>

        <div class="form-group">
            @Html.LabelFor(model => model.EntityList.List_EntitityName)
            @Html.DropDownListFor(model => model.AllGroups, new SelectList(Model.AllGroups),
                                    new { @class = "form-control" })
            <p class="help-block">@Html.ValidationMessageFor(model => model.EntityList.List_EntitityName)</p>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.EntityList.List_EntityValue)
            <input class="form-control" value="@Model.EntityList.List_EntityValue"/>
            <p class="help-block">@Html.ValidationMessageFor(model => model.EntityList.List_EntityValue)</p>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.EntityList.List_OrderByNumber)
            <input class="form-control" value="@Model.EntityList.List_OrderByNumber"/>
            <p class="help-block">@Html.ValidationMessageFor(model => model.EntityList.List_OrderByNumber)</p>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.EntityList.List_Comments)
            <textarea class="form-control" rows="3">@Model.EntityList.List_Comments</textarea>
            <p class="help-block">@Html.ValidationMessageFor(model => model.EntityList.List_Comments)</p>
        </div>

        <p>
            <input type="submit" value="Create" />
        </p>
    </fieldset>
}

当它到达“model.EntityList.List_CreatedTime = DateTime.Now;”时抛出空引用异常。

我尝试将签名更改为“public ActionResult Create（ListsModel ListsModel）”，如下所示：Create view is posting null objects 但我得到了同样的结果。

希望你能帮助我。

Answer 1

我认为问题在于您定义这样的输入的方式：

<input class="form-control" value="@Model.EntityList.List_EntityValue"/>

对于ASP MVC可以收集表单数据，输入应该具有与模型字段对应的Name属性。

尝试使用标准生成输入：

@Html.TextBoxFor(model => model.EntityList.List_EntityValue)

我建议你检查生成的html中的差异（看看asp mvc如何生成输入）。

MVC Create返回null对象

1 个答案: