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// Copyright 2021 Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package uuid
import (
"bytes"
"database/sql/driver"
"encoding/json"
"fmt"
)
// NullUUID represents a UUID that may be null.
// NullUUID implements the Scanner interface so
// it can be used as a scan destination:
//
// var u uuid.NullUUID
// err := db.QueryRow("SELECT name FROM foo WHERE id=?", id).Scan(&u)
// ...
// if u.Valid {
// // use u.UUID
// } else {
// // NULL value
// }
//
type NullUUID struct {
UUID UUID
Valid bool // Valid is true if UUID is not NULL
}
// Scan implements the Scanner interface.
func (nu *NullUUID) Scan(value interface{}) error {
if value == nil {
nu.UUID, nu.Valid = Nil, false
return nil
}
err := nu.UUID.Scan(value)
if err != nil {
nu.Valid = false
return err
}
nu.Valid = true
return nil
}
// Value implements the driver Valuer interface.
func (nu NullUUID) Value() (driver.Value, error) {
if !nu.Valid {
return nil, nil
}
// Delegate to UUID Value function
return nu.UUID.Value()
}
// MarshalBinary implements encoding.BinaryMarshaler.
func (nu NullUUID) MarshalBinary() ([]byte, error) {
if nu.Valid {
return nu.UUID[:], nil
}
return []byte(nil), nil
}
// UnmarshalBinary implements encoding.BinaryUnmarshaler.
func (nu *NullUUID) UnmarshalBinary(data []byte) error {
if len(data) != 16 {
return fmt.Errorf("invalid UUID (got %d bytes)", len(data))
}
copy(nu.UUID[:], data)
nu.Valid = true
return nil
}
// MarshalText implements encoding.TextMarshaler.
func (nu NullUUID) MarshalText() ([]byte, error) {
if nu.Valid {
return nu.UUID.MarshalText()
}
return []byte{110, 117, 108, 108}, nil
}
// UnmarshalText implements encoding.TextUnmarshaler.
func (nu *NullUUID) UnmarshalText(data []byte) error {
id, err := ParseBytes(data)
if err != nil {
nu.Valid = false
return err
}
nu.UUID = id
nu.Valid = true
return nil
}
// MarshalJSON implements json.Marshaler.
func (nu NullUUID) MarshalJSON() ([]byte, error) {
if nu.Valid {
return json.Marshal(nu.UUID)
}
return json.Marshal(nil)
}
// UnmarshalJSON implements json.Unmarshaler.
func (nu *NullUUID) UnmarshalJSON(data []byte) error {
null := []byte{110, 117, 108, 108}
if bytes.Equal(data, null) {
return nil // valid null UUID
}
var u UUID
// tossing as we know u is valid
_ = json.Unmarshal(data, &u)
nu.Valid = true
nu.UUID = u
return nil
}
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