C# SDK: How to determine if GetObjectAsync succeeded?

When accessing an object with a key that does not exist, the stream provided by GetObjectAsync contains an XML error and does not throw and error when read, How should a caller avoid returning this XML error string in place of an actual string? I realize it is possible to call StatObjectAsync first, but that raises concerns about what happens if stat is called first, then before getobject a remove call is made.

Expected Behavior

I would expect an exception from GetObjectAsync if the object could not be retrieved.

Current Behavior

The stream contains an XML string:

<?xml version="1.0" encoding="UTF-8"?>
<Error><Code>NoSuchKey</Code><Message>The specified key does not exist.</Message><Resource>/storagetest.f7f3da7a3a0b4ff299794b47161dccf6/Key Not Found</Resource><RequestId>15704FE60F942D64</RequestId><HostId>3L137</HostId></Error>

Possible Solution

• Provide a separate callback for the missing object scenario
• Provide a null stream
• Throw an exception

Steps to Reproduce (for bugs)

Call GetObjectAsync and provide a non-existing object key.

Context

I am concerned about concurrency problems with remove operations.

Your Environment

• Version used (minio version): 2018-12-13T02:04:19Z
• Environment name and version (e.g. nginx 1.9.1): n/a
• Server type and version: n/a
• Operating System and version (uname -a): Windows 10
• Link to your project: n/a

[nitisht]

fixed by #260

[poornas]

ok, I see a bug in this GetObjectAsync api call where we are not doing a stat prior to fetching - will fix it.

 public async Task GetObjectAsync(string bucketName, string objectName, long offset, long length, Action<Stream> cb, ServerSideEncryption sse = null,CancellationToken cancellationToken = default(CancellationToken))

The other API call should work -

 public async Task GetObjectAsync(string bucketName, string objectName, string fileName,ServerSideEncryption sse = null, CancellationToken cancellationToken = default(CancellationToken))