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MONGOC_CLIENT_T(3) libmongoc MONGOC_CLIENT_T(3)

A single-threaded MongoDB connection. See Connection Pooling.

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.

October 9, 2024 1.28.1