| 930 | } |
| 931 | |
| 932 | func ExampleCursor_reverse() { |
| 933 | // Open the database. |
| 934 | db, err := bolt.Open(tempfile(), 0600, nil) |
| 935 | if err != nil { |
| 936 | log.Fatal(err) |
| 937 | } |
| 938 | defer os.Remove(db.Path()) |
| 939 | |
| 940 | // Start a read-write transaction. |
| 941 | if err := db.Update(func(tx *bolt.Tx) error { |
| 942 | // Create a new bucket. |
| 943 | b, err := tx.CreateBucket([]byte("animals")) |
| 944 | if err != nil { |
| 945 | return err |
| 946 | } |
| 947 | |
| 948 | // Insert data into a bucket. |
| 949 | if err := b.Put([]byte("dog"), []byte("fun")); err != nil { |
| 950 | log.Fatal(err) |
| 951 | } |
| 952 | if err := b.Put([]byte("cat"), []byte("lame")); err != nil { |
| 953 | log.Fatal(err) |
| 954 | } |
| 955 | if err := b.Put([]byte("liger"), []byte("awesome")); err != nil { |
| 956 | log.Fatal(err) |
| 957 | } |
| 958 | |
| 959 | // Create a cursor for iteration. |
| 960 | c := b.Cursor() |
| 961 | |
| 962 | // Iterate over items in reverse sorted key order. This starts |
| 963 | // from the last key/value pair and updates the k/v variables to |
| 964 | // the previous key/value on each iteration. |
| 965 | // |
| 966 | // The loop finishes at the beginning of the cursor when a nil key |
| 967 | // is returned. |
| 968 | for k, v := c.Last(); k != nil; k, v = c.Prev() { |
| 969 | fmt.Printf("A %s is %s.\n", k, v) |
| 970 | } |
| 971 | |
| 972 | return nil |
| 973 | }); err != nil { |
| 974 | log.Fatal(err) |
| 975 | } |
| 976 | |
| 977 | // Close the database to release the file lock. |
| 978 | if err := db.Close(); err != nil { |
| 979 | log.Fatal(err) |
| 980 | } |
| 981 | |
| 982 | // Output: |
| 983 | // A liger is awesome. |
| 984 | // A dog is fun. |
| 985 | // A cat is lame. |
| 986 | } |