Postgresql – How to SELECT using a json aggregate function that takes two columns as key: value pair?

Supposing I have something like

What query do I need to run in order to SELECT/return a json like

>Solution :

Having

create table users ("Name" varchar, username varchar);

It would be

select array_to_json(array_agg( concat('{"',"Name",'": "',username,'"}')::json)) from users;

Working sample here