Question

我们正在制作电影评级网络应用程序，但我们遇到错误对象引用未设置为对象的实例。即使我们在导航回评级页面时出现错误，评级也会增加。

位指示：

  public ActionResult RateMedia(string Item, int Rate)
    {
        PopMediaDDL();
        var userStore = new UserStore<ApplicationUser>(ldb);
        var manager = new UserManager<ApplicationUser>(userStore);
        var user = manager.FindById(User.Identity.GetUserId());
        MediaRating rate = new MediaRating();
        rate.Title = ldb.MediaData.First(c => c.MediaName == Item);
        rate.Rating = Rate;
        rate.RateFor = user;
        ldb.MediaRatingData.Add(rate);
        ldb.SaveChanges();
        return View();
    }

型号：

 public class MediaRating
{
    [Key]
    public int MediaRatingID { get; set; }
    public virtual ApplicationUser RateFor { get; set; }
    public virtual Media Title { get; set; }
    public int Rating { get; set; }
}

查看：

     @using CollectionCompanion.Extensions
     @using CollectionCompanion.Models;
     @model CollectionCompanion.Models.UserCollectionItem
     <h2>Rate Media!</h2>
     <hr />
     @using (Html.BeginForm())
     {
     <div style="width:80%;">
     <div id="AddColItem">
        @Html.AntiForgeryToken()
      @Html.TextBoxFor(m => m.Item, new { @id = "MediaItem",@style=           "color:black;", @name = "MediaItem", @class = "form-control" })
    </div>
    <div id="AddColDD">
        <select id="Rate" name="Rate">
            <option value="1">1</option>
            <option value="2">2</option>
            <option value="3">3</option>
            <option value="4">4</option>
            <option value="5">5</option>
        </select>
    </div>
    <div id="AddColBTN">
        <input type="hidden" name="UserCollection" value="@ViewBag.UserCollectionID" />
        <button type="submit" class="btn btn-default btn-info"><span class="glyphicon glyphicon-plus"></span> Add</button>
    </div>
</div>

}

    @foreach (MediaRating rating in ViewBag.Ratings)
    {
    <div>
    <div style="width:50%;">
        @rating.Title.MediaName
    </div>
    <div style="width:50%">
        @rating.Rating
    </div>
    </div>
    }
    <script type="text/javascript">
    $("#MediaItem").autocomplete({
    change: function (event, ui) { },
    source: "../../Media/GetMediaResult/",
    minLength: 2

    }
    );
    </script>

Answer 1

您将在控制器操作结束时返回没有模型的视图：

f(x) = x

我怀疑您获得了空引用异常，因为您没有提供填充视图所需的模型和ViewBag。它应该看起来类似于HttpGet控制器操作，因为它提供了构建View所需的一切。

ASP.Net抛出错误但仍然发布数据

1 个答案: