Missing NullUint64 implementation (for pgx driver)

null_uint.go

package main

import (
	"context"
	"database/sql"
	"database/sql/driver"
	"fmt"
	"strconv"
	"time"

	_ "github.com/jackc/pgx/v5/stdlib"
	_ "github.com/lib/pq"
)

type NullUint64 struct {
	Uint64 uint64
	Valid  bool
}

func (n *NullUint64) Scan(value any) error {
	if value == nil {
		n.Uint64 = 0
		n.Valid = false
		return nil
	}

	s, ok := value.(string)
	if !ok {
		return fmt.Errorf("NullUint64.Scan got wrong type: %T", value)
	}

	var err error
	n.Uint64, err = strconv.ParseUint(s, 10, 64)
	if err != nil {
		return fmt.Errorf("NullUint64.Scan parse failed: %w", err)
	}

	n.Valid = true

	return nil
}

// Won't work with standard drivers like `lib/pq` that does not support uint types.
func (n NullUint64) Value() (driver.Value, error) {
	if !n.Valid {
		return nil, nil
	}
	return n.Uint64, nil
}

func main() {
	// change pgx to postgres to switch to lib/pg driver (will fail to insert)
	db, err := sql.Open("pgx", "postgres://postgres:postgres@localhost:5432/postgres?sslmode=disable")
	if err != nil {
		panic(err)
	}
	defer db.Close()

	val := NullUint64{^uint64(0), true}
	fmt.Println(val.Uint64)

	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	tx, err := db.BeginTx(ctx, nil)
	if err != nil {
		panic(err)
	}
	defer tx.Rollback()

	if _, err := tx.Exec("create table ttt (x numeric(30))"); err != nil {
		panic(err)
	}
	// actually can still make it work with lib/pq to like this:
	// tx.Exec("insert into ttt values($1::numeric)", strconv.FormatUint(val,10))
	if _, err := tx.Exec("insert into ttt values($1)", val); err != nil {
		panic(err)
	}

	var got NullUint64
	if err := tx.QueryRow("select x from ttt limit 1").Scan(&got); err != nil {
		panic(err)
	}

	fmt.Println(got.Uint64)
}