A select max(column) returns an interface{} which is useless!

[pdenapo]

Version

1.28.0

What happened?

I have the following query

-- name: Obtener_maximo :one
SELECT max(columna) from tabla;

[ columna in integer primary key in sqlite]

The generated code is like this

func (q *Queries) Obtener_maximo(ctx context.Context) (interface{}, error) {
row := q.db.QueryRowContext(ctx, obtener_maximo)
var max interface{}
err := row.Scan(&max)
return max, err
}

The problem with this code is that it returns a interface{} that can be of any type, which is useless. Instead, it should return an sql.NullInt64

It is enough to change the declaration of the max variable as

var max sql.NullInt64

A solution would be add an optional type to the query anotation like

-- name: Obtener_maximo :one sql.NullInt64
SELECT max(columna) from tabla;

to be used in the generated code.

[pdenapo]

It turns out that you can use the result of the query via a type assertion like

value,_ := Obtener_maximo().(int64)

I didn't realize that. May be it should be better explained in the documentation.