SYNOPSIS

          typedef struct _mongoc_client_t mongoc_client_t;

          typedef mongoc_stream_t *(*mongoc_stream_initiator_t) (
             const mongoc_uri_t *uri,
             const mongoc_host_list_t *host,
             void *user_data,
             bson_error_t *error);

       mongoc_client_t  is  an  opaque  type  that  provides access to a MongoDB server, replica set, or sharded
       cluster. It maintains management  of  underlying  sockets  and  routing  to  individual  nodes  based  on
       mongoc_read_prefs_t <> or mongoc_write_concern_t <>.

STREAMS

       The  underlying transport for a given client can be customized, wrapped or replaced by any implementation
       that fulfills mongoc_stream_t <>. A custom transport can be set with mongoc_client_set_stream_initiator()
       <>.

THREAD SAFETY

       mongoc_client_t is NOT thread-safe and should only be used from one  thread  at  a  time.  When  used  in
       multi-threaded  scenarios,  it  is  recommended  that  you use the thread-safe mongoc_client_pool_t <> to
       retrieve a mongoc_client_t for your thread.

FORK SAFETY

       A mongoc_client_t <> is only usable in the parent process after a  fork.  The  child  process  must  call
       mongoc_client_reset() <>.

EXAMPLE

       example-client.c

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

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

          #include <mongoc/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 *collection_name = "test";
             bson_t query;
             char *str;
             const char *uri_string = "mongodb://127.0.0.1/?appname=client-example";
             mongoc_uri_t *uri;

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

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

             uri = mongoc_uri_new_with_error(uri_string, &error);
             if (!uri) {
                fprintf(stderr,
                        "failed to parse URI: %s\n"
                        "error message:       %s\n",
                        uri_string,
                        error.message);
                return EXIT_FAILURE;
             }

             client = mongoc_client_new_from_uri(uri);
             if (!client) {
                return EXIT_FAILURE;
             }

             mongoc_client_set_error_api(client, 2);

             bson_init(&query);
             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_canonical_extended_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_uri_destroy(uri);
             mongoc_client_destroy(client);
             mongoc_cleanup();

             return EXIT_SUCCESS;
          }

Author

       MongoDB, Inc

Copyright

       2009-present, MongoDB, Inc.

2.2.1                                             Dec 11, 2025                                MONGOC_CLIENT_T(3)