asp.net-mvc - 用于 asp.net mvc 的回形针

Question

是否存在像 Paperclip for Rails 这样的插件？

实现自己的系统来上传文件并调整其大小真的很痛苦......

拥有模型属性会很酷，它会像这样获取参数:

型号:

[Paperclip(Sizes={thumb="100x20",big="200x40"},Path="~/public/")]
public string Image{get;set;}

查看:

Html.Editor(x=>x.Image)

here is small tutorial for rails .

Answer 1

看起来这个问题很老了，我偶然发现了它，因为它似乎还没有答案，我决定带上我的 2 美分。

我不知道 ASP.NET 是否存在这样的插件，但编写一个非常容易:

[AttributeUsage(AttributeTargets.Property)]
public class PaperClipAttribute : Attribute, IMetadataAware
{
    public PaperClipAttribute(string uploadPath, params string[] sizes)
    {
        if (string.IsNullOrEmpty(uploadPath))
        {
            throw new ArgumentException("Please specify an upload path");
        }

        UploadPath = uploadPath;
        Sizes = sizes;
    }

    public string UploadPath { get; private set; }
    public string[] Sizes { get; private set; }

    public void OnMetadataCreated(ModelMetadata metadata)
    {
        metadata.AdditionalValues["PaperClip"] = this;
    }
}

然后为 HttpPostedFileBase 类型定义自定义模型绑定(bind)器:

public class PaperClipModelBinder : DefaultModelBinder
{
    public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        var paperClip = bindingContext.ModelMetadata.AdditionalValues["PaperClip"] as PaperClipAttribute;
        if (paperClip == null)
        {
            return base.BindModel(controllerContext, bindingContext);
        }

        var uploadedFile = base.BindModel(controllerContext, bindingContext) as HttpPostedFileBase;
        if (uploadedFile == null)
        {
            return null;
        }

        var uploadPath = controllerContext.HttpContext.Server.MapPath(paperClip.UploadPath);
        if (!Directory.Exists(uploadPath))
        {
            throw new ArgumentException(string.Format("The specified folder \"{0}\" does not exist", uploadPath));
        }
        var sizes =
            (from size in paperClip.Sizes
             let tokens = size.Split('x')
             select new Size(int.Parse(tokens[0]), int.Parse(tokens[1]))
            ).ToArray();

        foreach (var size in sizes)
        {
            var extension = Path.GetExtension(uploadedFile.FileName);
            var outputFilename = Path.Combine(
                uploadPath,
                Path.ChangeExtension(
                    string.Format("image{0}x{1}", size.Width, size.Height),
                    extension
                )
            );
            Resize(uploadedFile.InputStream, outputFilename, size);
        }

        return base.BindModel(controllerContext, bindingContext);
    }

    private void Resize(Stream input, string outputFile, Size size)
    {
        using (var image = Image.FromStream(input))
        using (var bmp = new Bitmap(size.Width, size.Height))
        using (var gr = Graphics.FromImage(bmp))
        {
            gr.CompositingQuality = CompositingQuality.HighSpeed;
            gr.SmoothingMode = SmoothingMode.HighSpeed;
            gr.InterpolationMode = InterpolationMode.HighQualityBicubic;
            gr.DrawImage(image, new Rectangle(0, 0, size.Width, size.Height));
            bmp.Save(outputFile);
        }
    }
}

将在Application_Start中注册:

protected void Application_Start()
{
    AreaRegistration.RegisterAllAreas();

    RegisterGlobalFilters(GlobalFilters.Filters);
    RegisterRoutes(RouteTable.Routes);
    ModelBinders.Binders[typeof(HttpPostedFileBase)] = new PaperClipModelBinder();
}

我们已经完成了。剩下的都是经典的东西。

查看模型:

public class MyViewModel
{
    [PaperClip("~/App_Data", "100x20", "200x40", "640x480")]
    [Required(ErrorMessage = "Please select a file to upload")]
    public HttpPostedFileBase Image { get; set; }
}

Controller :

public class HomeController : Controller
{
    public ActionResult Index()
    {
        return View(new MyViewModel());
    }

    [HttpPost]
    public ActionResult Index(MyViewModel model)
    {
        if (!ModelState.IsValid)
        {
            return View(model);
        }
        return Content("thanks for uploading");
    }
}

查看:

@model MyViewModel

@using (Html.BeginForm(null, null, FormMethod.Post, new { enctype = "multipart/form-data" }))
{ 
    @Html.LabelFor(x => x.Image)
    <input type="file" name="image" />
    @Html.ValidationMessageFor(x => x.Image)
    <input type="submit" value="Upload" />
}