html - 通过查看将照片和视频保存在数据库中

Question

我有一个登录和注销程序。我有一个练习课，我有一个创建视图，允许我创建由名称、照片、视频组成的练习。我在查看创建中填写表格，当我单击创建时出现此错误

NullReferenceException: Object reference not set to an instance of an object.
WebApplication1.Controllers.ExerciciosGinasiosController.Create(ExerciciosGinasio exerciciosGinasio, IFormFile fotografia, IFormFile video) in ExerciciosGinasiosController.cs

            string nome_ficheiro = Path.GetFileName(fotografia.FileName);

在我的运动课上

 [Table("Exercicios_Ginasio")]
    public partial class ExerciciosGinasio
    {
        public ExerciciosGinasio()
        {
            Inclui = new HashSet<Inclui>();
        }

        [Key]
        [Column("IDExercicios_Ginasio")]
        public int IdexerciciosGinasio { get; set; }
        [Required]
        [Column("nome")]
        [StringLength(30)]
        public string Nome { get; set; }
        [Required]
        [Column("texto_descritivo")]
        [StringLength(1000)]
        public string TextoDescritivo { get; set; }
        [Required]
        [Column("foto")]

        public string Foto { get; set; }
        [Required]
        [Column("video")]

        public string Video { get; set; }

        [InverseProperty("IdexerciciosGinasioNavigation")]
        public virtual ICollection<Inclui> Inclui { get; set; }
    }
}

在属于练习类（ExercisesController）的控制器中，我有这个方法来创建一个新的练习

 [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Create([Bind("IdexerciciosGinasio,Nome,TextoDescritivo,Foto,Video")] ExerciciosGinasio exerciciosGinasio, IFormFile fotografia,IFormFile video)
        {
            string caminho = Path.Combine(_hostEnviroment.ContentRootPath, "wwwroot\\Exercicios");

            string nome_ficheiro = Path.GetFileName(fotografia.FileName);
            string caminho_completo = Path.Combine(caminho, nome_ficheiro);

            FileStream fs = new FileStream(caminho_completo, FileMode.Create);
            fotografia.CopyTo(fs);
            exerciciosGinasio.Foto = caminho_completo;
            fs.Close();




            string caminho2 = Path.Combine(_hostEnviroment.ContentRootPath, "wwwroot\\Exercicios");

            string nome_ficheiro2 = Path.GetFileName(video.FileName);
            string caminho_completo2 = Path.Combine(caminho2, nome_ficheiro2);

            FileStream _fs = new FileStream(caminho_completo2, FileMode.Create);
            video.CopyTo(_fs);
            exerciciosGinasio.Video = caminho_completo2;
            _fs.Close();

            if (ModelState.IsValid)
            {

                _context.Add(exerciciosGinasio);
                await _context.SaveChangesAsync();
                return RedirectToAction(nameof(Index));
            }
            return View(exerciciosGinasio);
        }

鉴于这种方法，我有

@model WebApplication1.Models.ExerciciosGinasio

@{
    ViewData["Title"] = "Create";
}


<h4>Criar Exercicio</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        <form asp-action="Create" enctype="multipart/form-data">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <div class="form-group">
                <label asp-for="Nome" class="control-label"></label>
                <input asp-for="Nome" class="form-control" />
                <span asp-validation-for="Nome" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="TextoDescritivo" class="control-label"></label>
                <input asp-for="TextoDescritivo" type="text" class="form-control" />
                <span asp-validation-for="TextoDescritivo" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Foto" class="control-label"></label>
                <input asp-for="Foto" type="file" class="form-control" accept=".png, .jpg, .bmp" value="" />
                @*<span asp-validation-for="Foto" class="text-danger"></span>*@

                <div>
                    <input type="hidden" name="fotografia" value="0" />
                </div>
                <div class="form-group">
                    <label asp-for="Video" class="control-label"></label>
                    <input asp-for="Video" type="file" class="form-control" />
                    @*<span asp-validation-for="Video" class="text-danger"></span>*@
                </div>
                <div>
                    <input type="hidden" name="video" value="0" />
                </div>
                <div class="form-group">
                    <input type="submit" value="Create" class="btn btn-primary" />
                </div>
        </form>
    </div>
</div>
<br />

<div>
    <a asp-action="Index" asp-controller="Home">Voltar</a>
</div>

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

有谁知道可能导致此错误的原因？我该如何解决

标签： htmlasp.net-core

Answer 1

NullReferenceException：对象引用未设置为对象的实例。

string nome_ficheiro = Path.GetFileName(fotografia.FileName);

在您的视图页面中，我们可以发现您正在使用默认值为 0 的隐藏字段fotografia和video，但您的Create操作需要通过IFormFile对象的文件，如果您调试代码，您会发现fotografianull ，这会导致异常，而您读取FileName的属性fotografia。

要修复它，您可以修改如下代码。

照片和视频的输入

<div class="form-group">
    <label asp-for="Foto" class="control-label"></label>
    <input type="file" class="form-control" name="fotografia" accept=".png, .jpg, .bmp" />
</div>
<div>
    <input type="hidden" name="Foto" value="0" />
</div>
<div class="form-group">
    <label asp-for="Video" class="control-label"></label>
    <input type="file" name="fvideo" class="form-control" />
</div>
<div>
    <input type="hidden" name="Video" value="0" />
</div>

控制器动作

[HttpPost]
public IActionResult Create([Bind("IdexerciciosGinasio,Nome,TextoDescritivo,Foto,Video")] ExerciciosGinasio exerciciosGinasio, 
    IFormFile fotografia, 
    IFormFile fvideo)
{
    string nome_ficheiro = Path.GetFileName(fotografia.FileName);

    //code logic here

        
    return View(exerciciosGinasio);
}  

测试结果