'ipfs dag patch'

[whyrusleeping]

I recently chatted with a user who is using ipfs object patch to maintain a KV storage tree in ipfs. We should look into adding a patch command to ipfs dag so that users of object patch can migrate.

Note that this isnt quite as simple to implement as ipfs object patch is, but should still be doable under certain constraints.

[Stebalien]

Personally, I'd use (something like) JSON Patch. We could even use IPLD objects as patches.

> ipfs dag patch apply QmObj QmPatch1 QmPatch2...
> ipfs dag patch apply QmId < patch.json
> ipfs dag patch add QmObj /path "value"
...

However, we'll need a general purpose dag encoder system to get this working properly (we currently only have a general purpose dag decoder system).

[schomatis]

Waiting to resolve #4801 before tackling this since many of the decisions there will also apply here.

[lidel]

Relevant IPLD spec: https://ipld.io/specs/patch/