表单提交时控制器动作方法的模型参数为空

Question

我在电影控制器中有一个动作方法 ReleasingTheaters，ReleasingTheaters 有两个重载一个是 httpGet，它接受电影 ID 并做一些事情并返回接受 ViewModel 对象的 ReleasingTheaters 视图。当我提交表单时，在 ReleasingTheaters 视图上点击提交按钮，控制器的另一个 http Post 操作方法 ReleasingTheaters 接受 viewModel 并将模型数据保存到数据库。

这是我的视图模型：

 public class MovieReleasingTheatersViewModel
 {
    public MovieReleasingTheatersViewModel()
    {
        AvailableStates = new List<SelectListItem>();
        AvailableCities = new List<SelectListItem>();
        AvailableLocations = new List<SelectListItem>();
        ReleasingTheaters = new List<MovieReleasingTheaterModel>();
    }

    [Display(Name="State")]
    public int? StateId { get; set; }  
    public IList<SelectListItem> AvailableStates { get; set; }
    [Display(Name = "City")]
    public int? CityId { get; set; }
    public IList<SelectListItem> AvailableCities { get; set; }
    public int? LocationId { get; set; }
    public IList<SelectListItem> AvailableLocations { get; set; }
    public IList<MovieReleasingTheaterModel> ReleasingTheaters { get; set; }
}

这是我的控制：

    [HttpGet]
    public ActionResult ReleasingTheaters(int id)
    {
        var model = new MovieReleasingTheatersViewModel();

        model = PrepareMovieReleasingTheaterModel(0, 0, 0, id);

        return View(model);
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult ReleasingTheaters(MovieReleasingTheatersViewModel model)
    {
        // iterate through the model's collection and save or update database
        return View("Index");
    }

这是我的 ReleasingTheaters 视图：

 @model Bookmany.Admin.Models.Movie.MovieReleasingTheatersViewModel

 @{
     ViewBag.Title = "Releasing Theaters";
  }

<h3>Releasing Theaters</h3>

@using (Html.BeginForm())
{
 @Html.AntiForgeryToken()
 <table class="table">
    <tr>
        <th>

            @Html.DropDownListFor(model => model.StateId, Model.AvailableStates, "Select  State")

        </th>
        <th>
            @Html.DropDownListFor(model => model.CityId, Model.AvailableCities, "Select City")
        </th>
        <th>
            @Html.DropDownListFor(model => model.LocationId, Model.AvailableLocations, "Select Location")
        </th>

        <th></th>
    </tr>
</table>

<table class="table">
<thead class="t_head">
    <tr>
        <th>
            Theater
        </th>
        <th>
            Date From
        </th>
        <th>
            Date To
        </th>
        <th>
            Release
        </th>
        <th></th>
    </tr>
</thead>
<tbody class="t_body">
    @foreach (var item in Model.ReleasingTheaters)
    {
        <tr>
            <td>

                @Html.DisplayFor(modelItem => item.TheaterName)
            </td>
            <td>
                @Html.TextBoxFor(modelItem => item.DateFrom, new { id = "DateFrom" })
            </td>
            <td>
                @Html.TextBoxFor(modelItem => item.DateTo, new { id = "DateTo" })
            </td>
            <td>
                @Html.EditorFor(modelItem => item.IsTheaterChecked)
            </td>
        </tr>
    }
</tbody>
</table>
   <div class="form-group">
        <div class="col-md-offset-2 col-md-10">
            <input type="submit" value="Save" class="btn btn-default" />
        </div>
    </div> 
    }

我的问题：

当我单击提交按钮时，动作方法上的模型对象没有值，viewModel 对象的集合属性都是空的，我的代码有什么问题

如何在我的操作方法上获取模型对象值（集合），以便我可以将这些值保存或更新回我的数据库

Answer 1

您需要将foreach 更改为for 循环，以便正确命名控件并可以由DefaultModelBinder 绑定

@for (int i = 0; i < Model.ReleasingTheaters.Count; i++)
{
  @Html.TextBoxFor(m => m.ReleasingTheaters[i].DateFrom)
  ....
}

这将生成诸如

之类的输入

<input type="text" name="ReleasingTheaters[0].DateFrom" id="ReleasingTheaters_0__DateFrom" value="?" >
<input type="text" name="ReleasingTheaters[1].DateFrom" id="ReleasingTheaters_1__DateFrom" value="?" >

还请注意，您不应该将id 属性设置为new { id = "DateFrom" } 等。助手将呈现一个唯一的ID，但您正在创建重复的ID，这是无效的html