I'd like to get such properties of a music file as its artwork, duration, file size. But I do not find these properties in "entry" in the "result.entries" array.
The Dropbox API does not extract and return media information such as artwork and duration for audio files, but I'll pass this along as a feature request. I can't promise if or when that might be implemented though. That being the case, to access this information, you'd need to download the file and extract the desired information from the audio file data.
The Dropbox API does return file size information, but you'll need to cast the Metadata as FileMetadata first, like in this example, to access the properties specific to FileMetadata. Then you can access FileMetadata.size.
