BlockBlobClient.UploadAsync 尝试修改传入的 WatchableReadStream 对象时失败

Question

我希望你能给我一些建议，因为我几乎别无选择。我想做什么：

通过 Azure 门户将图像上传到 blobcontainer
这样做时，下面的 blobtrigger 会触发。
我想调整作为 Microsoft.Azure.WebJobs.Host.Blobs.WatchableReadStream 对象的传入图像的大小。
我想将结果上传到新的 blob 容器。

问题是，当我超过任何其他 Stream，例如MemoryStream 比未修改的 myBlob 对象 UploadAsync 方法似乎无声地失败并且 BlobTrigger 再次触发，开始无限循环。写入当前 myBlob 对象也无提示地失败。唯一有效的是在 BlockBlobClient.UploadAsync 中传递 myBlob 对象而不进行任何修改，这是无用的。我正在 Azure 中进行远程调试会话。

此外，当我尝试将 MemoryStream 对象提供给 UploadAsync 方法时，也会出现同样的问题。下面的方法是 blob 触发器：

        public async Task UploadImage([BlobTrigger("mediafullsizecontainer/{name}", Connection = "AzureWebJobsStorage")]Stream myBlob, string name, ILogger log)
        {
            BlockBlobClient fullsizeBlobClient = _mediaFullsizeContainerClient.GetBlockBlobClient(name);
            Response<BlobProperties> blobPropertiesResponse = await fullsizeBlobClient.GetPropertiesAsync(null, default);

            BlobProperties blobProperties = blobPropertiesResponse.Value;

            //Only process blobs when the correct metadata properties are set
            if (blobProperties.Metadata.Any(property => property.Key == "category" & property.Value != String.Empty))
            {
                string category = blobProperties.Metadata["category"];

                Stream s = await ResizeImage(myBlob);

                BlockBlobClient thumbnailBlobclient = _mediaThumbnailContainerClient.GetBlockBlobClient(name);
                Response<BlobContentInfo> uploadResponse = await thumbnailBlobclient.UploadAsync(s, new BlobUploadOptions(), default);
                
                BlobContentInfo blobContentInfo = uploadResponse.Value;
            }
        }

ResizeImage 方法使用 SixLabors.ImageSharp 图像处理库。

        public async Task<Stream> ResizeImage(Stream inputStream)
        {
            (Image image, IImageFormat imageFormat) imageWithFormat = await Image.LoadWithFormatAsync(inputStream);
            int height = imageWithFormat.image.Height;
            int width = imageWithFormat.image.Width;

            imageWithFormat.image.Mutate(operation => {
                operation.Resize(width / 4, height / 4);
            });

            MemoryStream outputStream = new MemoryStream();
            imageWithFormat.image.Save(outputStream, imageWithFormat.imageFormat);

            return outputStream;
        }

所以当我像这样对 myBlob 对象进行模拟更改时，myBlob.Write(buffer) 失败了：

                byte[] buffer = new byte[myBlob.Length];
                myBlob.Read(buffer, 0, (int)myBlob.Length);

                myBlob.Position = 0;
                myBlob.Write(buffer);

当我将 myBlob 内容复制到 MemoryStream 并将 memoryStream 传递给 UploadAsync 时，UploadAsync 失败：

                MemoryStream ms = new MemoryStream();
                myBlob.CopyTo(ms);
                 
                BlockBlobClient thumbnailBlobclient = _mediaThumbnailContainerClient.GetBlockBlobClient(name);
                Response<BlobContentInfo> uploadResponse = await thumbnailBlobclient.UploadAsync(ms, new BlobUploadOptions(), default);

唯一可行的是在不对 UploadAsync 进行任何修改的情况下传递 myBlob 对象，这是无用的，因为我需要修改传入流：

        public async Task UploadImage([BlobTrigger("mediafullsizecontainer/{name}", Connection = "AzureWebJobsStorage")]Stream myBlob, string name, ILogger log)
        {
            BlockBlobClient fullsizeBlobClient = _mediaFullsizeContainerClient.GetBlockBlobClient(name);
            Response<BlobProperties> blobPropertiesResponse = await fullsizeBlobClient.GetPropertiesAsync(null, default);

            BlobProperties blobProperties = blobPropertiesResponse.Value;

            //Only process blobs when the correct metadata properties are set
            if (blobProperties.Metadata.Any(property => property.Key == "category" & property.Value != String.Empty))
            {
                string category = blobProperties.Metadata["category"];

                BlockBlobClient thumbnailBlobclient = _mediaThumbnailContainerClient.GetBlockBlobClient(name);
                Response<BlobContentInfo> uploadResponse = await thumbnailBlobclient.UploadAsync(myBlob, new BlobUploadOptions(), default);
                
                BlobContentInfo blobContentInfo = uploadResponse.Value;
            }
        }

如何将自定义流传递给 UploadAsync 方法？ https://docs.microsoft.com/en-us/dotnet/api/azure.storage.blobs.specialized.blockblobclient.uploadasync?view=azure-dotnet 上的文档说您只需要一个流对象 - 但这是行不通的。提前致谢。

Answer 1

好吧，看来我自己找到了答案，我摆脱了可怕的 UploadAsync 方法，并通过将调整大小的图像的 outputStream 读入缓冲区然后打开 outputStream 来做到这一点=13=] 用于写入 thumbnailBlobclient 对象并将缓冲区传递给流对象。尝试修改触发器附带的传入 myBlob 对象，再次触发触发器并创建循环是有道理的。

                Stream outputStream = await ResizeAndCropImage(myBlob);
                byte[] buffer = new byte[outputStream.Length];
                outputStream.Read(buffer);

                BlockBlobClient thumbnailBlobclient = _mediaThumbnailContainerClient.GetBlockBlobClient(name);
                Stream s = thumbnailBlobclient.OpenWrite(true, new BlockBlobOpenWriteOptions { HttpHeaders = new BlobHttpHeaders { ContentType = "image/jpg" } }, default); //set http headers here as well?

                await s.WriteAsync(buffer);
                s.Close();

我将以更通用的方式设置内容类型，但这个概念很有效。

BlockBlobClient.UploadAsync 尝试修改传入的 WatchableReadStream 对象时失败

BlockBlobClient.UploadAsync fails when trying to modify the incoming WatchableReadStream object

upload

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