Allow narrowing key result space

[harrisi]

It could be nice to change GET /library/keys to accept a prefix to include in the results, as in:

GET /library/keys
(returns all keys)
GET /library/keys?foo
(returns all keys starting with 'foo')

This would be handy in the case where someone has a significant amount of files in a folder, potentially deeply nested, and a client needs to make a decision about how to download the folder. See #11.

[GianniCarlo]

adding to this, just thought to mention that a prefix (> 'all keys starting with') may catch other items not contained in a folder, e.g.

foo.mp3
foo/pilot.mp3
foo/sequel.mp3
foo bar/other.mp3

so just for clarification, the intent is just for a given folder's contents right?

[harrisi]

The way I wrote the issue, yes it would just be to get a folder's contents, but after thinking about it more, this can be generalized to accommodate search features, which is probably a more useful thing to do.

Currently the search strategy for GET /library?relativePath=foo does match similarly to your example, but it doesn't give the nested items. The results of GET /library?relativePath=foo with your structure would be:

{
  "content": [
    {
      "relativePath": "foo.mp3",
      "...": "..."
    },
    {
      "relativePath": "foo",
      "...": "..."
    },
    {
      "relativePath": "foo bar",
      "...": "..."
    }
  ]
}