How to construct a jsonb containing a number?

Question

Is there a way to construct a jsonb with only a numeric value in it?

For example,

SELECT pg_typeof(('{"a":1}'::jsonb) -> 'a');

indicates that ('{"a":1}'::jsonb) -> 'a' has the jsonb type and it only contains a numeric value 1.

But how do I create a jsonb with 1 in it directly without constructing and destructing an object?

Direct type casting does not seem to work:

# SELECT 1::jsonb;
ERROR: cannot cast type integer to jsonb
LINE 1: SELECT 1::jsonb;

Answer 1

You need to cast from a string, not from a number: '1'::jsonb. This is because using '1' means that the result is actually a constant, whereas 1 is a runtime conversion.

to_jsonb(1) also works, but I think this uses a runtime conversion.

SELECT pg_typeof('1'::jsonb), jsonb_typeof('1'::jsonb);

pg_typeof	jsonb_typeof
jsonb	number

db<>fiddle