Object Storage Service:Resolving zero-byte MemoryStream uploads

Problem

When using the .NET SDK to upload a file from a MemoryStream, the upload operation may succeed, but the resulting file in OSS has a size of 0 bytes. This issue occurs because writing data to the MemoryStream moves the file pointer to the end of the stream.

Solution

1. Before passing the stream to the upload method, reset the file pointer to the beginning of the stream by calling mStream.Seek(0, SeekOrigin.Begin);.

   public static void MemStreamUpload()
   {
       Uri endPoint = new Uri("http://oss-cn-beijing.aliyuncs.com");
       string accessKeyID = "your_access_key_id";
       string accessKeySecret = "your_access_key_secret";
       string bucketName = "your_bucket_name";
       string key = "ossobject.jpg";
       string filepath = @"D:\1.jpg";
   
       ObjectMetadata metadata = new ObjectMetadata();
       // You can set custom metadata.
       metadata.UserMetadata.Add("myfield", "test");
   
       OssClient ossClient = new OssClient(endPoint, accessKeyID, accessKeySecret);
   
       MemoryStream mStream = new MemoryStream();
       Image image = Image.FromFile(filepath);
       image.Save(mStream, ImageFormat.Jpeg);
   
       mStream.Seek(0, SeekOrigin.Begin);
   
       PutObjectResult putObjectResult = ossClient.PutObject(bucketName, key, mStream, metadata);
       Console.WriteLine(putObjectResult.ETag);
   }

2. Verify that the uploaded file has the correct size.