Question

Net我试图进行编辑以上传图像，但现在每当我编辑它时崩溃并给出＆＃39; System.ArgumentNullException＆＃39;发生在System.Core.dll中但未在用户代码中处理＆＃39;。这一切都始于我试图实现图像上传的编辑。它在edit.cshtml页面上崩溃，我在崩溃的地方放置了一条评论。任何帮助将非常感谢，如果您需要更多信息，请告诉我

AnimalsController

  [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Edit([Bind(Include = "LatinNameID,CommonNameID,LatinName,CommonName,GenusID,SpeciesID,Description,FamilyID,CountryID,ContinentID,OrderID")] Animal animal, HttpPostedFileBase upload,string latinID,string commonID)
    {

        var animalToUpdate = db.Animals.Find(latinID,commonID);

        //Does a check to see if entry exists in database
        if ((db.Animals.Any(ac => ac.LatinName.Equals(animal.LatinName))) || (db.Animals.Any(ac => ac.CommonName.Equals(animal.CommonName))))
        {
            ModelState.AddModelError("LatinName", "Already Exists");
            ModelState.AddModelError("CommonName", "Duplicate Entry");
        }
        else
        {
            if (ModelState.IsValid)
            {
                if (upload != null && upload.ContentLength > 0)
                {
                    if (animalToUpdate.Files.Any(f => f.FileType == FileType.Avatar))
                    {
                        db.File.Remove(animalToUpdate.Files.First(f => f.FileType == FileType.Avatar));
                    }
                    var avatar = new File
                    {
                        FileName = System.IO.Path.GetFileName(upload.FileName),
                        FileType = FileType.Avatar,
                        ContentType = upload.ContentType
                    };
                    using (var reader = new System.IO.BinaryReader(upload.InputStream))
                    {
                        avatar.Content = reader.ReadBytes(upload.ContentLength);
                    }
                    animalToUpdate.Files = new List<File> { avatar };
                }
                db.Entry(animal).State = EntityState.Modified;
                db.SaveChanges();
                return RedirectToAction("Index");
            }
        }

        ViewBag.ContinentID = new SelectList(db.Continents, "ContinentID", "ContinentName", animal.ContinentID);
        ViewBag.CountryID = new SelectList(db.Countries, "CountryID", "CountryName", animal.CountryID);
        ViewBag.FamilyID = new SelectList(db.Families, "FamilyID", "FamilyName", animal.FamilyID);
        ViewBag.GenusID = new SelectList(db.Genus, "GenusID", "GenusName", animal.GenusID);
        ViewBag.OrderID = new SelectList(db.Orders, "OrderID", "OrderName", animal.OrderID);
        ViewBag.SpeciesID = new SelectList(db.Species, "SpeciesID", "SpeciesName", animal.SpeciesID);
        return View(animal);
    }

修改视图

<h2>Edit</h2>


@using (Html.BeginForm("Edit", "Animals", null, FormMethod.Post, new { enctype = "multipart/form-data" }))
{
 @Html.AntiForgeryToken()

<div class="form-horizontal">
    <h4>Animal</h4>
    <hr />
    @Html.ValidationSummary(true, "", new { @class = "text-danger" })
    @Html.HiddenFor(model => model.LatinNameID)

    @Html.HiddenFor(model => model.CommonNameID)

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

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

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

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

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

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

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

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

    <div class="form-group">
        @Html.LabelFor(model => model.OrderID, "OrderID", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownList("OrderID", null, htmlAttributes: new { @class = "form-control" })
            @Html.ValidationMessageFor(model => model.OrderID, "", new { @class = "text-danger" })
        </div>
    </div>
    //Crashes here
    @if (Model.Files.Any(f => f.FileType == FileType.Avatar))
    {
        <div class="form-group">
            <span class="control-label col-md-2"><strong>Current Avatar</strong></span>
            <div class="col-md-10">
                <img src="~/File?id=@Model.Files.First(f => f.FileType == FileType.Avatar).FileId" alt="avatar" />
            </div>
        </div>
    }


    <div class="form-group">
        @Html.Label("Avatar", new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            <input type="file" id="Avatar" name="upload" />
        </div>
    </div>

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

<div>
@Html.ActionLink("Back to List", "Index")
</div>

@section Scripts {
@Scripts.Render("~/bundles/jqueryval")
}

模型

//Animal
public class Animal
{
    [Key, Column(Order = 0)]
    public string LatinNameID { get; set; }
    public string LatinName { get; set; }

    [Key, Column(Order = 1)]
    public string CommonNameID { get; set; }
    public string CommonName { get; set; }

    public string GenusID { get; set; }

    public string SpeciesID { get; set; }

    public string Description { get; set; }

    public string FamilyID { get; set; }

    public string CountryID { get; set; }

    public string ContinentID { get; set; }

    public string OrderID { get; set; }

    public virtual Continent Continent { get; set; }

    public virtual Genus Genus { get; set; }

    public virtual Species Species { get; set; }

    public virtual Family Family { get; set; }

    public virtual Country Country { get; set; }

    public virtual Order Order { get; set; }

    public virtual ICollection<File> Files { get; set; }
}

//File
 public class File
{
    public int FileId { get; set; }
    [StringLength(255)]
    public string FileName { get; set; }
    [StringLength(100)]
    public string ContentType { get; set; }
    public byte[] Content { get; set; }
    public FileType FileType { get; set; }
    public string LatinNameID { get; set; }
    public string CommonNameID { get; set; }
    public virtual Animal Animal { get; set; }
}

Answer 1

您收到的错误表明您在代码中的某处调用了一个带有null参数的方法。由于它以Model.Files.Any(f => f.FileType == FileType.Avatar)开头的if语句崩溃，我会在继续之前验证Model.Files是否为空。

代码可能如下所示：

@if (Model.Files != null && Model.Files.Any(f => f.FileType == FileType.Avatar))
{
    <div class="form-group">
        <span class="control-label col-md-2"><strong>Current Avatar</strong></span>
        <div class="col-md-10">
            <img src="~/File?id=@Model.Files.First(f => f.FileType == FileType.Avatar).FileId" alt="avatar" />
        </div>
    </div>
}

如果Model.Files永远不应该为null，那么您可能需要调查为什么没有设置该值。

System.ArgumentNullException＆＃39;发生在System.Core.dll中但未在用户代码中处理

1 个答案: