How to get only the jsonb of specific keys from postgres?

Question

I\'m aware that you can remove keys from a jsonb in postgres using something like this

select \'{\"a\": 1, \"b\": 2, \"c\":3}\'::jsonb -\'a\';
 ?column?
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Answer 1

You can get just the value like so:

 select '{"a": 1, "b": 2}'::jsonb-> 'a';

If you must, you can transform that back into jsonb manually, or perhaps go through an array, hstore or other intermediate type. Here's the "manual" way

 select ('{ "a": '||('{"a": 1, "b": 2}'::jsonb->'a')::text||'}')::jsonb