function sign(json, unknown) does not exist - jwt

Question

I'm following the tutorial on https://postgrest.org/en/v5.0/auth.html#jwt-from-sql
I created this function:
create or replace function
login(email text, pass text) returns basic_auth.jwt_token
language plpgsql
as $$
declare
_role name;
result basic_auth.jwt_token;
begin
-- check email and password
select basic_auth.user_role(email, pass) into _role;
if _role is null then
raise invalid_password using message = 'invalid user or password';
end if;
select sign(
row_to_json(r), 'reallyreallyreallyreallyverysafe'
) as token
from (
select _role as role, login.email as email,
extract(epoch from now())::integer + 60*60 as exp
) r
into result;
return result;
end;
$$;
When I try to do the login request, I get the following error message:
{
"hint": "No function matches the given name and argument types. You might need to add explicit type casts.",
"details": null,
"code": "42883",
"message": "function public.sign(json, unknown) does not exist" }
I don't see the sign function anywhere in the tutorial, does anyone know what is going on here?

Answer 1

The sign function is created when you install pgjwt.
Also, make sure that you install the extension on a schema that is included in your search_path(a list of imported schemas). This can be specified by doing CREATE EXTENSION pgjwt WITH SCHEMA public.
PostgREST adds the public schema by default on the search_path, so the extension should work with no additional config.