Amazon S3: How to get a list of folders in the bucket?

Question

The only thing I've found, it's this method GET Bucket.
But I can't understand how can I get only a list of folders in the current folder. What prefix and delimiter do I need to use? Is that possible at all?

Answer 1

Using prefix of the/path/to/read/ (note that there is no leading slash, but there is a trailing slash), and delimiter of /, you'll find all the folders within that folder inside <CommonPrefixes>.

CommonPrefixes

A response can contain CommonPrefixes only if you specify a delimiter. When you do, CommonPrefixes contains all (if there are any) keys between Prefix and the next occurrence of the string specified by delimiter. In effect, CommonPrefixes lists keys that act like subdirectories in the directory specified by Prefix. For example, if prefix is notes/ and delimiter is a slash (/), in notes/summer/july, the common prefix is notes/summer/. All of the keys rolled up in a common prefix count as a single return when calculating the number of returns. See MaxKeys.

http://docs.aws.amazon.com/AmazonS3/latest/API/RESTBucketGET.html

Answer 2

What Anthony is missing here is that a folder doesn't necessarily have a key associated with it. If a file is created in S3, and given a key like "folder/name.ext", S3 will display a "folder" folder, but it doesn't have a key, meaning you're not getting it in your results.

The only way to catch these folders is to look at the keys themselves, and regex the key name for the "/" character. If I knew C# a little better, I'd write you a code sample, but for reference here's a python example I wrote on another question.