1// Copyright 2021 Google Inc. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package uuid
6
7import (
8 "bytes"
9 "database/sql/driver"
10 "encoding/json"
11 "fmt"
12)
13
14var jsonNull = []byte("null")
15
16// NullUUID represents a UUID that may be null.
17// NullUUID implements the SQL driver.Scanner interface so
18// it can be used as a scan destination:
19//
20// var u uuid.NullUUID
21// err := db.QueryRow("SELECT name FROM foo WHERE id=?", id).Scan(&u)
22// ...
23// if u.Valid {
24// // use u.UUID
25// } else {
26// // NULL value
27// }
28//
29type NullUUID struct {
30 UUID UUID
31 Valid bool // Valid is true if UUID is not NULL
32}
33
34// Scan implements the SQL driver.Scanner interface.
35func (nu *NullUUID) Scan(value interface{}) error {
36 if value == nil {
37 nu.UUID, nu.Valid = Nil, false
38 return nil
39 }
40
41 err := nu.UUID.Scan(value)
42 if err != nil {
43 nu.Valid = false
44 return err
45 }
46
47 nu.Valid = true
48 return nil
49}
50
51// Value implements the driver Valuer interface.
52func (nu NullUUID) Value() (driver.Value, error) {
53 if !nu.Valid {
54 return nil, nil
55 }
56 // Delegate to UUID Value function
57 return nu.UUID.Value()
58}
59
60// MarshalBinary implements encoding.BinaryMarshaler.
61func (nu NullUUID) MarshalBinary() ([]byte, error) {
62 if nu.Valid {
63 return nu.UUID[:], nil
64 }
65
66 return []byte(nil), nil
67}
68
69// UnmarshalBinary implements encoding.BinaryUnmarshaler.
70func (nu *NullUUID) UnmarshalBinary(data []byte) error {
71 if len(data) != 16 {
72 return fmt.Errorf("invalid UUID (got %d bytes)", len(data))
73 }
74 copy(nu.UUID[:], data)
75 nu.Valid = true
76 return nil
77}
78
79// MarshalText implements encoding.TextMarshaler.
80func (nu NullUUID) MarshalText() ([]byte, error) {
81 if nu.Valid {
82 return nu.UUID.MarshalText()
83 }
84
85 return jsonNull, nil
86}
87
88// UnmarshalText implements encoding.TextUnmarshaler.
89func (nu *NullUUID) UnmarshalText(data []byte) error {
90 id, err := ParseBytes(data)
91 if err != nil {
92 nu.Valid = false
93 return err
94 }
95 nu.UUID = id
96 nu.Valid = true
97 return nil
98}
99
100// MarshalJSON implements json.Marshaler.
101func (nu NullUUID) MarshalJSON() ([]byte, error) {
102 if nu.Valid {
103 return json.Marshal(nu.UUID)
104 }
105
106 return jsonNull, nil
107}
108
109// UnmarshalJSON implements json.Unmarshaler.
110func (nu *NullUUID) UnmarshalJSON(data []byte) error {
111 if bytes.Equal(data, jsonNull) {
112 *nu = NullUUID{}
113 return nil // valid null UUID
114 }
115 err := json.Unmarshal(data, &nu.UUID)
116 nu.Valid = err == nil
117 return err
118}