c# - 使用 ASP.NET Web API 将图像添加到 Azure Blob 存储失败

Question

我有一个用于存储图像的 Azure blob 容器。我还有一套 ASP.NET Web API 方法，用于添加/删除/列出此容器中的 blob。如果我将图像作为文件上传，这一切都有效。但我现在想将图像作为流上传，但出现错误。

public async Task<HttpResponseMessage> AddImageStream(Stream filestream, string filename)
    {
        try
        {
            if (string.IsNullOrEmpty(filename))
            {
                throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.BadRequest));
            }

            BlobStorageService service = new BlobStorageService();
            await service.UploadFileStream(filestream, filename, "image/png");
            var response = Request.CreateResponse(HttpStatusCode.OK);
            return response;
        }
        catch (Exception ex)
        {
            base.LogException(ex);
            throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.BadRequest));
        }

将新图像作为流添加到 blob 容器的代码如下所示。

public async Task UploadFileStream(Stream filestream, string filename, string contentType)
    {
        CloudBlockBlob blockBlobImage = this._container.GetBlockBlobReference(filename);
        blockBlobImage.Properties.ContentType = contentType;
        blockBlobImage.Metadata.Add("DateCreated", DateTime.UtcNow.ToLongDateString());
        blockBlobImage.Metadata.Add("TimeCreated", DateTime.UtcNow.ToLongTimeString());
        await blockBlobImage.UploadFromStreamAsync(filestream);
    }

最后这是我失败的单元测试。

[TestMethod]
    public async Task DeployedImageStreamTests()
    {
        string blobname = Guid.NewGuid().ToString();

        //Arrange
        MemoryStream stream = new MemoryStream(Encoding.UTF8.GetBytes($"This is a blob called {blobname}."))
        {
            Position = 0
        };

        string url = $"http://mywebapi/api/imagesstream?filestream={stream}&filename={blobname}";
        Console.WriteLine($"DeployedImagesTests URL {url}");
        HttpContent content = new StringContent(blobname, Encoding.UTF8, "application/json");
        var response = await ImagesControllerPostDeploymentTests.PostData(url, content);

        //Assert
        Assert.IsNotNull(response);
        Assert.IsTrue(response.IsSuccessStatusCode); //fails here!!
        Assert.AreEqual(HttpStatusCode.OK, response.StatusCode);
    }

我收到的错误是值不能为空。参数名称:来源

这是使用 Web API 将图像流上传到 Azure Blob 存储的正确方法吗？我可以毫无问题地处理图像文件，并且现在我尝试使用流上传时才遇到此问题。

Answer 1

Is this the correct way to upload an image stream to Azure blob storage using Web API? I have it working with image files without a problem, and only getting this problem now that I'm trying to upload using streams.

根据您的描述和错误消息，我发现您将网址中的流数据发送到Web api。

根据这篇文章:

Web API 使用以下规则来绑定(bind)参数:

如果参数是“简单”类型，Web API 会尝试从 URI 获取值。简单类型包括 .NET 基元类型(int、bool、double 等)，加上 TimeSpan、DateTime、Guid、decimal 和 string，以及带有可以从字符串转换的类型转换器的任何类型。 (稍后将详细介绍类型转换器。)

对于复杂类型，Web API 尝试使用媒体类型格式化程序从消息正文中读取值。

在我看来，流是一种复杂的类型，因此我建议您可以将其作为正文发布到 Web api。

此外，我建议您可以创建一个文件类并使用 Newtonsoft.Json 将其转换为 json 作为消息内容。

更多详情，可以引用下面的代码。文件类别:

  public class file
    {
        //Since JsonConvert.SerializeObject couldn't serialize the stream object I used byte[] instead
        public byte[] str { get; set; }
        public string filename { get; set; }

        public string contentType { get; set; }
    }

网络 API:

  [Route("api/serious/updtTM")]
    [HttpPost]
    public void updtTM([FromBody]file imagefile)
    {
            CloudStorageAccount storageAccount = CloudStorageAccount.Parse("aaaaa");
            var client = storageAccount.CreateCloudBlobClient();
            var container = client.GetContainerReference("images");

            CloudBlockBlob blockBlobImage = container.GetBlockBlobReference(imagefile.filename);
            blockBlobImage.Properties.ContentType = imagefile.contentType;
            blockBlobImage.Metadata.Add("DateCreated", DateTime.UtcNow.ToLongDateString());
            blockBlobImage.Metadata.Add("TimeCreated", DateTime.UtcNow.ToLongTimeString());

            MemoryStream stream = new MemoryStream(imagefile.str)
            {
                Position=0
            };
            blockBlobImage.UploadFromStreamAsync(stream);
        }

测试控制台:

 using (var client = new HttpClient())
            {
                string URI = string.Format("http://localhost:14456/api/serious/updtTM");
                file f1 = new file();

                byte[] aa = File.ReadAllBytes(@"D:\Capture2.PNG");

                f1.str = aa;
                f1.filename = "Capture2";
                f1.contentType = "PNG";
                var serializedProduct = JsonConvert.SerializeObject(f1); 
                var content = new StringContent(serializedProduct, Encoding.UTF8, "application/json");
                var result = client.PostAsync(URI, content).Result;
            }