It's All Writing.

Writing makes you happy.

multiple group by

How to implement multiple key's group by at node

Prerequisites There are arrays has multiple elements as below. [ { "name": "SHINCHI, Takahiro", "mail": "shinchi@its-all-writing.com", "hobby": "Walking" }, { "name": "SHINCHI, Takahiro", "mail": "shinchi.xx@gmail.com", "hobby": "Playing t…