1BSON_STREAMING_BSON(3)              libbson             BSON_STREAMING_BSON(3)
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bson_reader_t provides a streaming reader which can be initialized with a

6filedescriptor or memory region. bson_writer_t  provides  a  streaming  writer
7which  can  be initialized with a memory region. (Streaming BSON to a file de‐
8scriptor is not yet supported.)
9

READING FROM A BSON STREAM

11       bson_reader_t provides a convenient API to read sequential  BSON  docu‐
12       ments  from  a file-descriptor or memory buffer. The bson_reader_read()
13       function will read forward in the underlying stream and return a bson_t
14       that can be inspected and iterated upon.
15
16          #include <stdio.h>
17          #include <bson/bson.h>
18
19          int
20          main (int argc, char *argv[])
21          {
22             bson_reader_t *reader;
23             const bson_t *doc;
24             bson_error_t error;
25             bool eof;
26
27             reader = bson_reader_new_from_file ("mycollection.bson", &error);
28
29             if (!reader) {
30                fprintf (stderr, "Failed to open file.\n");
31                return 1;
32             }
33
34             while ((doc = bson_reader_read (reader, &eof))) {
35                char *str = bson_as_canonical_extended_json (doc, NULL);
36                printf ("%s\n", str);
37                bson_free (str);
38             }
39
40             if (!eof) {
41                fprintf (stderr,
42                         "corrupted bson document found at %u\n",
43                         (unsigned) bson_reader_tell (reader));
44             }
45
46             bson_reader_destroy (reader);
47
48             return 0;
49          }
50
51       See    bson_reader_new_from_fd(),    bson_reader_new_from_file(),   and
52       bson_reader_new_from_data() for more information.
53

WRITING A SEQUENCE OF BSON DOCUMENTS

55       bson_writer_t provides a convenient API to write  a  sequence  of  BSON
56       documents  to  a  memory  buffer  that  can  grow  with  realloc(). The
57       bson_writer_begin() and bson_writer_end() functions will manage the un‐
58       derlying buffer while building the sequence of documents.
59
60       This  could  also  be  useful  if you want to write to a network packet
61       while serializing the documents from a higher level language,  (but  do
62       so just after the packets header).
63
64          #include <stdio.h>
65          #include <bson/bson.h>
66          #include <assert.h>
67
68          int
69          main (int argc, char *argv[])
70          {
71             bson_writer_t *writer;
72             bson_t *doc;
73             uint8_t *buf = NULL;
74             size_t buflen = 0;
75             bool r;
76             int i;
77
78             writer = bson_writer_new (&buf, &buflen, 0, bson_realloc_ctx, NULL);
79
80             for (i = 0; i < 10000; i++) {
81                r = bson_writer_begin (writer, &doc);
82                assert (r);
83
84                r = BSON_APPEND_INT32 (doc, "i", i);
85                assert (r);
86
87                bson_writer_end (writer);
88             }
89
90             bson_free (buf);
91
92             return 0;
93          }
94
95       See bson_writer_new() for more information.
96

AUTHOR

98       MongoDB, Inc
99

101       2017-present, MongoDB, Inc
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1061.25.1                           Nov 08, 2023           BSON_STREAMING_BSON(3)
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