mongoc_cursor_t — MongoDB C Driver 1.6.3

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- API Reference

# mongoc_cursor_t

Client-side cursor abtraction

## Synopsis

    typedef struct _mongoc_cursor_t mongoc_cursor_t;

`mongoc_cursor_t` provides access to a MongoDB query cursor. It wraps up the wire protocol negotiation required to initiate a query and retrieve an unknown number of documents.

Cursors are lazy, meaning that no network traffic occurs until the first call to mongoc_cursor_next().

At that point we can:

- Determine which host we've connected to with mongoc_cursor_get_host().
- Retrieve more records with repeated calls to mongoc_cursor_next().
- Clone a query to repeat execution at a later point with mongoc_cursor_clone().
- Test for errors with mongoc_cursor_error().

## Thread Safety

`mongoc_cursor_t` is NOT thread safe. It may only be used from the thread it was created from.

## Example

Query MongoDB and iterate results

    /* gcc example-client.c -o example-client $(pkg-config --cflags --libs
     * libmongoc-1.0) */

    /* ./example-client [CONNECTION_STRING [COLLECTION_NAME]] */

    #include <mongoc.h>
    #include <stdio.h>
    #include <stdlib.h>

    int
    main (int argc, char *argv[])
    {
       mongoc_client_t *client;
       mongoc_collection_t *collection;
       mongoc_cursor_t *cursor;
       bson_error_t error;
       const bson_t *doc;
       const char *uristr = "mongodb://127.0.0.1/?appname=client-example";
       const char *collection_name = "test";
       bson_t query;
       char *str;

       mongoc_init ();

       if (argc > 1) {
          uristr = argv[1];
       }

       if (argc > 2) {
          collection_name = argv[2];
       }

       client = mongoc_client_new (uristr);

       if (!client) {
          fprintf (stderr, "Failed to parse URI.\n");
          return EXIT_FAILURE;
       }

       mongoc_client_set_error_api (client, 2);

       bson_init (&query);

    #if 0
       bson_append_utf8 (&query, "hello", -1, "world", -1);
    #endif

       collection = mongoc_client_get_collection (client, "test", collection_name);
       cursor = mongoc_collection_find_with_opts (
          collection,
          &query,
          NULL,  /* additional options */
          NULL); /* read prefs, NULL for default */

       while (mongoc_cursor_next (cursor, &doc)) {
          str = bson_as_json (doc, NULL);
          fprintf (stdout, "%s\n", str);
          bson_free (str);
       }

       if (mongoc_cursor_error (cursor, &error)) {
          fprintf (stderr, "Cursor Failure: %s\n", error.message);
          return EXIT_FAILURE;
       }

       bson_destroy (&query);
       mongoc_cursor_destroy (cursor);
       mongoc_collection_destroy (collection);
       mongoc_client_destroy (client);

       mongoc_cleanup ();

       return EXIT_SUCCESS;
    }

## Functions

- mongoc_cursor_clone()
- mongoc_cursor_current()
- mongoc_cursor_destroy()
- mongoc_cursor_error()
- mongoc_cursor_get_batch_size()
- mongoc_cursor_get_hint()
- mongoc_cursor_get_host()
- mongoc_cursor_get_id()
- mongoc_cursor_get_limit()
- mongoc_cursor_get_max_await_time_ms()
- mongoc_cursor_is_alive()
- mongoc_cursor_more()
- mongoc_cursor_new_from_command_reply()
- mongoc_cursor_next()
- mongoc_cursor_set_batch_size()
- mongoc_cursor_set_hint()
- mongoc_cursor_set_limit()
- mongoc_cursor_set_max_await_time_ms()

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