uuid
uuid/uuid.go
Add Copy() and IsZero() methods as helpers. Use id.Copy() to return a copy of the ID that shares nothing with the source ID. id.IsZero() returns true if the ID is equivalent to the zero value for the type.
1 package uuid
3 import (
4 "database/sql/driver"
5 "encoding/json"
6 "encoding/xml"
7 "errors"
9 "code.google.com/p/go-uuid/uuid"
10 )
12 var InvalidIDError = errors.New("Invalid ID format.")
14 type ID uuid.UUID
16 func NewID() ID {
17 return ID(uuid.NewRandom())
18 }
20 func (id ID) String() string {
21 return uuid.UUID(id).String()
22 }
24 func (id ID) IsZero() bool {
25 if id == nil {
26 return true
27 }
28 if len(id) == 0 {
29 return true
30 }
31 return false
32 }
34 func (id ID) Copy() ID {
35 resp, _ := Parse(id.String())
36 // ignore the error because they asked for a copy of the ID, they
37 // never asked if it was valid or not.
38 // This is, overall, not the most efficient way to do this (we're
39 // essentially converting to a string and then back again) but the
40 // computational complexity involved is pretty minor, and it allows
41 // us to respect the boundaries between the packages, using only the
42 // exported interfaces to perform a copy. And that seems pretty
43 // valuable.
44 return resp
45 }
47 func (id ID) MarshalJSON() ([]byte, error) {
48 return json.Marshal(id.String())
49 }
51 func (id ID) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
52 return e.EncodeElement(id.String(), start)
53 }
55 func (id ID) Value() (driver.Value, error) {
56 return id.String(), nil
57 }
59 func (id *ID) Scan(src interface{}) error {
60 if src == nil {
61 id = nil
62 return nil
63 }
64 switch src.(type) {
65 case []byte:
66 if len(src.([]byte)) == 0 {
67 *id = (*id)[:0]
68 return nil
69 }
70 newID, err := Parse(string(src.([]byte)))
71 if err != nil {
72 return err
73 }
74 *id = append((*id)[:0], newID...)
75 return nil
76 case string:
77 if len(src.(string)) == 0 {
78 *id = (*id)[:0]
79 return nil
80 }
81 newID, err := Parse(src.(string))
82 if err != nil {
83 return err
84 }
85 *id = append((*id)[:0], newID...)
86 return nil
87 default:
88 return InvalidIDError
89 }
90 return nil
91 }
93 func (id *ID) UnmarshalJSON(in []byte) error {
94 var tmp string
95 err := json.Unmarshal(in, &tmp)
96 if err != nil {
97 return err
98 }
99 newID, err := Parse(tmp)
100 if err != nil {
101 return err
102 }
103 *id = append((*id)[:0], newID...)
104 return nil
105 }
107 func (id *ID) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
108 var tmp string
109 err := d.DecodeElement(&tmp, &start)
110 if err != nil {
111 return err
112 }
113 newID, err := Parse(tmp)
114 if err != nil {
115 return err
116 }
117 *id = append((*id)[:0], newID...)
118 return nil
119 }
121 func Parse(in string) (ID, error) {
122 id := ID(uuid.Parse(in))
123 if id == nil {
124 return id, InvalidIDError
125 }
126 return id, nil
127 }
129 func (id ID) Equal(other ID) bool {
130 return uuid.Equal(uuid.UUID(id), uuid.UUID(other))
131 }