Golang implementation of sql.NullInt64 for int 32 (aka nullInt32)

sql_nullint.go

// NullInt32 is the equivalent of sql.NullInt64 but for 32-bits integers. It offers the guarantee that integers
// serialized or deserialized are in the range of math.MinInt32 to math.MaxInt32. Errors are returned by Scan() if
// that's not the case.
type NullInt32 struct {
	Int32 int
	Valid bool // Valid is true if Int32 is not NULL
}

func (n *NullInt32) Scan(value interface{}) error {
	var n64 sql.NullInt64
	if err := n64.Scan(value); err != nil {
		return err
	}

	if !n64.Valid {
		n.Int32 = 0
		n.Valid = false
		return nil
	}

	i64 := n64.Int64
	if i64 > math.MaxInt32 {
		return errors.New("value higher than max int32")
	}
	if i64 < math.MinInt32 {
		return errors.New("value lower than min int32")
	}

	n.Int32 = (int)(n64.Int64)
	n.Valid = true
	return nil
}

func (n NullInt32) Value() (driver.Value, error) {
	if !n.Valid {
		return nil, nil
	}
	return int64(n.Int32), nil
}