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);
    }

我得到的错误是值不能为空。参数名称：source

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，现在我正在尝试使用流上传时才遇到这个问题。

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信息，我发现您将 url 中的流数据发送到网络 api。

根据这篇文章：

Web API 使用以下规则绑定参数：

如果参数是 "simple" 类型，Web API 会尝试从 URI 中获取值。简单类型包括 .NET 基元类型（int、bool、double 等），加上 TimeSpan、DateTime、Guid、decimal 和 string，以及任何具有可以从字符串转换的类型转换器的类型。（稍后会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 post 将其作为正文发送到网络 api。

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

更多细节，您可以参考下面的代码。文件 class:

  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; }
    }

网页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;
            }

使用 ASP.NET Web API 将图像添加到 Azure blob 存储失败

Adding an image to Azure blob storage using ASP.NET Web API fails

c#

asp.net

azure

asp.net-web-api

azure-blob-storage