NullInt32 - could not determine data type of parameter $1

[Saticmotion]

I'm trying to run a query with an optional WHERE:

//userid is pgx.NullInt32
//count is int
//offset is int

//if userid.Valid is false this should evaluate to NULL is NULL, and thus not filter on userid 
rows, err := dbPool.Query(`SELECT id, userid, timestamp, downloadsize FROM videos
						WHERE ($1 IS NULL OR userid=$1) 
						LIMIT $2
						OFFSET $3`, userid, count, offset)

Table videos looks like:

id				uuid
userid			integer
timestamp		timestamp without timezone
downloadsize	integer

But this returns the error could not determine data type of parameter $1 (SQLSTATE 42P08). The error occurs both when userid.Valid is true and when false.

What am I doing wrong?

[jackc]

The problem is $1 IS NULL. pgx will use prepared statements under the hood. When preparing that statement PostgreSQL cannot infer what type $1 is. You can see the same thing in the psql client.

jack=# prepare ps as select 'foo' where $1 is null;
ERROR:  could not determine data type of parameter $1

Solution is to include a typecast.

jack=# prepare ps as select 'foo' where $1::int is null;
PREPARE

[Saticmotion]

Oohh I see! Thank you!