1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
|
package bolt
import (
"fmt"
"os"
)
func init() {
os.RemoveAll("/tmp/bolt")
os.MkdirAll("/tmp/bolt", 0777)
}
func ExampleDB_Update() {
// Open the database.
db, _ := Open("/tmp/bolt/db_do.db", 0666)
defer db.Close()
// Execute several commands within a write transaction.
err := db.Update(func(tx *Tx) error {
if err := tx.CreateBucket("widgets"); err != nil {
return err
}
b := tx.Bucket("widgets")
if err := b.Put([]byte("foo"), []byte("bar")); err != nil {
return err
}
return nil
})
// If our transactional block didn't return an error then our data is saved.
if err == nil {
db.View(func(tx *Tx) error {
value := tx.Bucket("widgets").Get([]byte("foo"))
fmt.Printf("The value of 'foo' is: %s\n", string(value))
return nil
})
}
// Output:
// The value of 'foo' is: bar
}
func ExampleDB_View() {
// Open the database.
db, _ := Open("/tmp/bolt/db_with.db", 0666)
defer db.Close()
// Insert data into a bucket.
db.Update(func(tx *Tx) error {
tx.CreateBucket("people")
tx.Bucket("people").Put([]byte("john"), []byte("doe"))
tx.Bucket("people").Put([]byte("susy"), []byte("que"))
return nil
})
// Access data from within a read-only transactional block.
db.View(func(tx *Tx) error {
v := tx.Bucket("people").Get([]byte("john"))
fmt.Printf("John's last name is %s.\n", string(v))
return nil
})
// Output:
// John's last name is doe.
}
func ExampleTx_Put() {
// Open the database.
db, _ := Open("/tmp/bolt/db_put.db", 0666)
defer db.Close()
// Start a write transaction.
db.Update(func(tx *Tx) error {
// Create a bucket.
tx.CreateBucket("widgets")
// Set the value "bar" for the key "foo".
tx.Bucket("widgets").Put([]byte("foo"), []byte("bar"))
return nil
})
// Read value back in a different read-only transaction.
db.Update(func(tx *Tx) error {
value := tx.Bucket("widgets").Get([]byte("foo"))
fmt.Printf("The value of 'foo' is: %s\n", string(value))
return nil
})
// Output:
// The value of 'foo' is: bar
}
func ExampleTx_Delete() {
// Open the database.
db, _ := Open("/tmp/bolt/db_delete.db", 0666)
defer db.Close()
// Start a write transaction.
db.Update(func(tx *Tx) error {
// Create a bucket.
tx.CreateBucket("widgets")
b := tx.Bucket("widgets")
// Set the value "bar" for the key "foo".
b.Put([]byte("foo"), []byte("bar"))
// Retrieve the key back from the database and verify it.
value := b.Get([]byte("foo"))
fmt.Printf("The value of 'foo' was: %s\n", string(value))
return nil
})
// Delete the key in a different write transaction.
db.Update(func(tx *Tx) error {
return tx.Bucket("widgets").Delete([]byte("foo"))
})
// Retrieve the key again.
db.View(func(tx *Tx) error {
value := tx.Bucket("widgets").Get([]byte("foo"))
if value == nil {
fmt.Printf("The value of 'foo' is now: nil\n")
}
return nil
})
// Output:
// The value of 'foo' was: bar
// The value of 'foo' is now: nil
}
func ExampleTx_ForEach() {
// Open the database.
db, _ := Open("/tmp/bolt/tx_foreach.db", 0666)
defer db.Close()
// Insert data into a bucket.
db.Update(func(tx *Tx) error {
tx.CreateBucket("animals")
b := tx.Bucket("animals")
b.Put([]byte("dog"), []byte("fun"))
b.Put([]byte("cat"), []byte("lame"))
b.Put([]byte("liger"), []byte("awesome"))
// Iterate over items in sorted key order.
b.ForEach(func(k, v []byte) error {
fmt.Printf("A %s is %s.\n", string(k), string(v))
return nil
})
return nil
})
// Output:
// A cat is lame.
// A dog is fun.
// A liger is awesome.
}
func ExampleBegin_ReadOnly() {
// Open the database.
db, _ := Open("/tmp/bolt/tx.db", 0666)
defer db.Close()
// Create a bucket.
db.Update(func(tx *Tx) error {
return tx.CreateBucket("widgets")
})
// Create several keys in a transaction.
tx, _ := db.Begin(true)
b := tx.Bucket("widgets")
b.Put([]byte("john"), []byte("blue"))
b.Put([]byte("abby"), []byte("red"))
b.Put([]byte("zephyr"), []byte("purple"))
tx.Commit()
// Iterate over the values in sorted key order.
tx, _ = db.Begin(false)
c := tx.Bucket("widgets").Cursor()
for k, v := c.First(); k != nil; k, v = c.Next() {
fmt.Printf("%s likes %s\n", string(k), string(v))
}
tx.Rollback()
// Output:
// abby likes red
// john likes blue
// zephyr likes purple
}
func ExampleTx_rollback() {
// Open the database.
db, _ := Open("/tmp/bolt/tx_rollback.db", 0666)
defer db.Close()
// Create a bucket.
db.Update(func(tx *Tx) error {
return tx.CreateBucket("widgets")
})
// Set a value for a key.
db.Update(func(tx *Tx) error {
return tx.Bucket("widgets").Put([]byte("foo"), []byte("bar"))
})
// Update the key but rollback the transaction so it never saves.
tx, _ := db.Begin(true)
b := tx.Bucket("widgets")
b.Put([]byte("foo"), []byte("baz"))
tx.Rollback()
// Ensure that our original value is still set.
db.View(func(tx *Tx) error {
value := tx.Bucket("widgets").Get([]byte("foo"))
fmt.Printf("The value for 'foo' is still: %s\n", string(value))
return nil
})
// Output:
// The value for 'foo' is still: bar
}
func ExampleDB_CopyFile() {
// Open the database.
db, _ := Open("/tmp/bolt/db_copy.db", 0666)
defer db.Close()
// Create a bucket and a key.
db.Update(func(tx *Tx) error {
tx.CreateBucket("widgets")
tx.Bucket("widgets").Put([]byte("foo"), []byte("bar"))
return nil
})
// Copy the database to another file.
db.CopyFile("/tmp/bolt/db_copy_2.db", 0666)
// Open the cloned database.
db2, _ := Open("/tmp/bolt/db_copy_2.db", 0666)
defer db2.Close()
// Ensure that the key exists in the copy.
db2.View(func(tx *Tx) error {
value := tx.Bucket("widgets").Get([]byte("foo"))
fmt.Printf("The value for 'foo' in the clone is: %s\n", string(value))
return nil
})
// Output:
// The value for 'foo' in the clone is: bar
}
|
