Support for hierarchical data

[McSinyx]

Or folders in plain English. AFAICT the following tasks needs to be supported through core's HTTP API:

• Create a new folder from existing data entries (files and folders): this should require metadata fields to POST /add. Create a new entry and return the content ID (CID) to the new folder.
• List entries in a folder: may support recursive walking? Error on file entries.
• Insert an entry into a folder or subfolder: create new entry with clone of metadata and return CID of new folder. Error if entry points to a single file.

/cc @larycoder and @npthao1312 for further discussion

[npthao1312]

Should both file and folder include source and topics? It feels like a bit of duplication.

[McSinyx]

Sorry for the late reply, and yes, that's a good point. I looked a bit deeper into this and apparently core API should provide a way to add files and directories without/with minimal metadata. I imagine there are two ways to do this:

1. Having a more versatile POST /add which can handle both file and folder (of multiple files and folders) upload. Implementing this as a multipart file upload is quite simple since I'll only need to proxy the request (with some headers modified) to IPFS, so it's up to you to decide if you want it (I've no idea how hard it is to implement on the caller side). Then we'll only need a POST /insert (or PUT /insert in case of mutable datasets) to cover all user cases.
2. Drop current POST /add in favor of lower-level calls, namely POST /save, POST /mkdir, POST /cp (files and folders into a folder) and a new POST /add which takes the metadata and the CID (instead of the data).

[npthao1312]

Either way is fine for me. But I would prefer 2.

[npthao1312]

Remember to update the API doc

[McSinyx]

@npthao1312, I've just published a new release with support for this, please refer to the updated documentation (which is technically still the same URI, relinked for convenience purposes).