Null types golang

nulltypes.go

// NullString is an alias for sql.NullString data type
type NullString struct {
	sql.NullString
}

// MarshalJSON for NullString
func (ns *NullString) MarshalJSON() ([]byte, error) {
	if !ns.Valid {
		return []byte("null"), nil
	}
	return json.Marshal(ns.String)
}

// NullInt64 is an alias for sql.NullInt64 data type
type NullInt64 struct {
	sql.NullInt64
}

// MarshalJSON for NullInt64
func (ni *NullInt64) MarshalJSON() ([]byte, error) {
	if !ni.Valid {
		return []byte("null"), nil
	}
	return json.Marshal(ni.Int64)
}

// NullFloat64 is an alias for sql.NullFloat64 data type
type NullFloat64 struct {
	sql.NullFloat64
}

// MarshalJSON for NullFloat64
func (nf *NullFloat64) MarshalJSON() ([]byte, error) {
	if !nf.Valid {
		return []byte("null"), nil
	}
	return json.Marshal(nf.Float64)
}