POSTing to RPC endpoint: mixing querystring and body

[tjoekbezoer]

I can't seem to figure out why this isn't working. If I understand correctly, I should be able to mix the querystring and body payload to provide my RPC with parameters. After testing, I've stripped my problem down to the fact that I apparently can't use the querystring to supply parameters. This is my test function:

create or replace function kvk.test(
	gmcode text
)
returns json
language sql
stable
as $$
	select
		json_build_object(
			'gmcode', gmcode
		)
$$;

Now, when I try to call this method via POST rpc/test?gmcode=1234 I'd expect it to give me back a JSON object in the form of {"gmcode": "1234"}, but instead I get this error:

{
  "code": "PGRST100",
  "details": "unexpected \"G\" expecting \"not\" or operator (eq, gt, ...)",
  "hint": null,
  "message": "\"failed to parse filter (GM1680)\" (line 1, column 1)"
}

Instead, if I supply the argument in the body of the request the rpc call works as expected. What am I missing?

PS: This is a stripped down test, the original function requires more arguments that are passed in the body of the POST request. The reason I want gmcode to be passed in the query string is because it will be set by the proxy server handling the user request — the user will not be able to set it themselves. I figured that manipulating the querystring will be the easiest way to achieve this goal.

[wolfgangwalther]

Querystring arguments are not supported for POST. See also #3562.

[tjoekbezoer]

That issue didn't come up in my search, thanks. I'll continue there.