"INTERVAL $1" is not parameterized

[haoliangyu]

I have a query like this

UPDATE
  my_table
SET
  expire_after = now() + INTERVAL $1
RETURNING *

and try to parameterize the query with

pg.query(my_query, ['30 seconds'])

It doesn't work and throws an error :-(

ERROR:  syntax error at or near "$1" at character xxx

[charmander]

INTERVAL '…' is an interval literal; you would use $1::interval to interpret a parameter as an interval. (Passing [30] and adding $1 * INTERVAL '1 second' might also be appropriate.)

[haoliangyu]

The $1::interval doesn't work for me but the $1 * INTERVAL '1 second' works. Thanks for the tips.