[Boost-users] Uploading a file to a Boost Beast Server

I am using Beast 277 and code from the advanced server example as the basis for my own one. As part of the functionality I need to allow users the ability to upload a file to the server via their browser. So I had a look at the 'Deferred Body Type' in the examples provided but I can't see how I can make use of it in my own server, although I have tried but fall foul of the SyncReadStream. Is there a working example anywhere of how I can capture and save a file uploaded to the server by a user please. -- Bill