如何在webapi上传中获取Multipart文件的流? [英] How to get the stream for a Multipart file in webapi upload?

问题描述

我需要使用Stream(Azure Blobstorage)上传文件，但是无法找出如何从对象本身获取流.参见下面的代码.

I need to upload a file using Stream (Azure Blobstorage), and just cannot find out how to get the stream from the object itself. See code below.

我是WebAPI的新手，并使用了一些示例.我正在获取文件和文件数据，但这不是我上传方法的正确类型.因此，我需要获取或将其转换为正常的Stream，此刻这似乎有点困难:)

I'm new to the WebAPI and have used some examples. I'm getting the files and filedata, but it's not correct type for my methods to upload it. Therefore, I need to get or convert it into a normal Stream, which seems a bit hard at the moment :)

我知道我需要以某种方式使用ReadAsStreamAsync().Result，但是由于我有两个提供者，因此它会在foreach循环中崩溃.内容(第一个看起来正确，第二个看起来不正确).

I know I need to use ReadAsStreamAsync().Result in some way, but it crashes in the foreach loop since I'm getting two provider.Contents (first one seems right, second one does not).

 [System.Web.Http.HttpPost]
    public async Task<HttpResponseMessage> Upload()
    {
        if (!Request.Content.IsMimeMultipartContent())
        {
            this.Request.CreateResponse(HttpStatusCode.UnsupportedMediaType);
        }

        var provider = GetMultipartProvider();
        var result = await Request.Content.ReadAsMultipartAsync(provider);

        // On upload, files are given a generic name like "BodyPart_26d6abe1-3ae1-416a-9429-b35f15e6e5d5"
        // so this is how you can get the original file name
        var originalFileName = GetDeserializedFileName(result.FileData.First());

        // uploadedFileInfo object will give you some additional stuff like file length,
        // creation time, directory name, a few filesystem methods etc..
        var uploadedFileInfo = new FileInfo(result.FileData.First().LocalFileName);



        // Remove this line as well as GetFormData method if you're not
        // sending any form data with your upload request
        var fileUploadObj = GetFormData<UploadDataModel>(result);

        Stream filestream = null;

        using (Stream stream = new MemoryStream())
        {
            foreach (HttpContent content in provider.Contents)
            {
                BinaryFormatter bFormatter = new BinaryFormatter();
                bFormatter.Serialize(stream, content.ReadAsStreamAsync().Result);
                stream.Position = 0;
                filestream = stream;
            }
        }

        var storage = new StorageServices();
        storage.UploadBlob(filestream, originalFileName);**strong text**



private MultipartFormDataStreamProvider GetMultipartProvider()
    {
        var uploadFolder = "~/App_Data/Tmp/FileUploads"; // you could put this to web.config
        var root = HttpContext.Current.Server.MapPath(uploadFolder);
        Directory.CreateDirectory(root);
        return new MultipartFormDataStreamProvider(root);
    }

推荐答案

这与我几个月前遇到的困境相同(在MultipartStreamProvider接管之前捕获上传流并将其自动神奇地保存到文件).建议是继承该类并重写方法……但这在我的情况下不起作用. :((我想将MultipartFileStreamProvider和MultipartFormDataStreamProvider的功能都集成到一个MultipartStreamProvider中，而没有自动保存的部分.)

This is identical to a dilemma I had a few months ago (capturing the upload stream before the MultipartStreamProvider took over and auto-magically saved the stream to a file). The recommendation was to inherit that class and override the methods ... but that didn't work in my case. :( (I wanted the functionality of both the MultipartFileStreamProvider and MultipartFormDataStreamProvider rolled into one MultipartStreamProvider, without the autosave part).

这可能会有所帮助； 这是由一位Web API开发人员和

This might help; here's one written by one of the Web API developers, and this from the same developer.

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