Selecting a subsection of jsonb

Question

Given table events:

create table events (
  id integer,
  data jsonb
)

How would one construct a query such that we return only select keys in the results column?

say we had the record in the events table:

(1, {"a": 1, "b": 2})

Is it possible to return something like:

id | data
1  | {"b": 2}

Answer 1

Straightforward, using jsonb_build_object:

create temporary table events(id, data) 
as values (1, '{"a":1, "b":2, "c":"three"}'::jsonb);

select id, jsonb_build_object(
  'b', data -> 'b', 
  'c', data -> 'c'
) from events; 

id	jsonb_build_object
1	{"b": 2, "c": "three"}