使用ViewModel提交POST创建游戏事件失败求助

我正在开发一个可创建游戏事件的网站，原本创建新事件时直接输入GameID，现在为了让用户选择游戏名称而非输入ID，改用ViewModel实现。页面的游戏下拉列表显示正常，但点击提交按钮后仅刷新页面，数据库无新增数据，POST请求返回200状态码且无报错。不使用ViewModel时创建功能正常。

ViewModel及实体类定义 #

public class EventCreateVM
{
    public Events Event { get; set; }
    public IEnumerable<SelectListItem> Games { get; set; }
}

public class Events
{
    public int EventID { get; set; }
    public int GameID { get; set; }
    [DisplayName("Event Name")]
    public string EventName { get; set; }
    public string Server { get; set; }
    [DisplayName("Max Players")]
    public int MaxPlayers { get; set; }
    public string Type { get; set; }
    public string Platform { get; set; }
    public string Description { get; set; }
    [DisplayName("Event Time")]
    public DateTime DateTime { get; set; }
}

视图代码（适配ViewModel） #

@model AgileTeamFour.UI.ViewModels.EventCreateVM

@{
    ViewData["Title"] = "Create";
}
<h1>Create</h1>

<h4>Events</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        <form asp-action="Create" asp-controller="Event">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
           @*  <div class="form-group">
                <label asp-for="Event.EventID" class="control-label"></label>
                <input asp-for="Event.EventID" class="form-control" />
                <span asp-validation-for="Event.EventID" class="text-danger"></span>
            </div> *@
            <div class="form-group">
    <label asp-for="Event.GameID" class="control-label"></label>
    <select asp-for="Event.GameID" class="form-control" asp-items="Model.Games"></select>
    <span asp-validation-for="Event.GameID" class="text-danger"></span>
</div>
            <div class="form-group">
                <label asp-for="Event.EventName" class="control-label"></label>
                <input asp-for="Event.EventName" class="form-control" />
                <span asp-validation-for="Event.EventName" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Event.Server" class="control-label"></label>
                <input asp-for="Event.Server" class="form-control" />
                <span asp-validation-for="Event.Server" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Event.MaxPlayers" class="control-label"></label>
                <input asp-for="Event.MaxPlayers" class="form-control" />
                <span asp-validation-for="Event.MaxPlayers" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Event.Type" class="control-label"></label>
                <input asp-for="Event.Type" class="form-control" />
                <span asp-validation-for="Event.Type" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Event.Platform" class="control-label"></label>
                <input asp-for="Event.Platform" class="form-control" />
                <span asp-validation-for="Event.Platform" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Event.Description" class="control-label"></label>
                <input asp-for="Event.Description" class="form-control" />
                <span asp-validation-for="Event.Description" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Event.DateTime" class="control-label"></label>
                <input asp-for="Event.DateTime" class="form-control" />
                <span asp-validation-for="Event.DateTime" class="text-danger"></span>
            </div>
            <div class="form-group">
                <input type="submit" value="Create" class="btn btn-primary" />
            </div>
        </form>
    </div>
</div>

<div>
    <a asp-action="Index">Back to List</a>
</div>

@section Scripts {
    @{await Html.RenderPartialAsync("_ValidationScriptsPartial");}
}

控制器代码 #

public ActionResult Create()
{
    var games = GameManager.Load(); 
    var viewModel = new EventCreateVM
    {
        Event = new Events(),
        Games = games.Select(g => new SelectListItem
        {
            Value = g.GameID.ToString(),
            Text = g.GameName
        }).ToList()
    };
    return View(viewModel);
}

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create(EventCreateVM viewmodel)
{
    try
    {
        if (ModelState.IsValid)
        {
            int eventID = 0;
            EventManager.Insert(ref eventID, viewmodel.Event.GameID, viewmodel.Event.EventName, viewmodel.Event.Server, viewmodel.Event.MaxPlayers, viewmodel.Event.Type, viewmodel.Event.Platform, viewmodel.Event.Description, viewmodel.Event.DateTime);
            return RedirectToAction(nameof(Index));
        }
        return View(viewmodel);
    }
    catch
    {
        return View();
    }
}

排查建议 #

• 检查模型验证细节：在POST方法开头添加调试代码，查看所有模型验证错误：

  var errors = ModelState.Values.SelectMany(v => v.Errors);
  

  asp-validation-summary="ModelOnly"仅显示模型级错误，字段级验证失败可能被隐藏，导致ModelState.IsValid为false但页面无提示。

• 重新填充下拉列表数据源：当模型验证失败返回视图时，viewmodel.Games会丢失数据，需重新加载并赋值：

  if (!ModelState.IsValid)
  {
      var games = GameManager.Load();
      viewmodel.Games = games.Select(g => new SelectListItem
      {
          Value = g.GameID.ToString(),
          Text = g.GameName
      }).ToList();
      return View(viewmodel);
  }
  

• 验证数据传递完整性：用浏览器开发者工具查看POST请求的Form Data，确认所有字段（尤其是Event.GameID、Event.EventName等）是否正确发送到服务器。

• 修复异常处理逻辑：当前catch块直接返回空视图，丢失错误信息，改为记录异常并返回带错误提示的视图：

  catch (Exception ex)
  {
      ModelState.AddModelError("", $"创建失败：{ex.Message}");
      var games = GameManager.Load();
      viewmodel.Games = games.Select(g => new SelectListItem
      {
          Value = g.GameID.ToString(),
          Text = g.GameName
      }).ToList();
      return View(viewmodel);
  }
  

• 检查EventManager.Insert方法：确认该方法是否正确处理参数，是否有内部吞掉的异常，可在方法内添加日志或直接调试参数值是否符合数据库要求。

内容的提问来源于stack exchange，提问作者Jimmy Dictus