MongoDB C Driver

Introduction

Welcome to the documentation site for the official MongoDB C driver. You can add the driver to your application to work with MongoDB in C. Download the required libraries, libmongoc and libbson, by following the Obtaining the MongoDB C Driver Libraries instructions or set up a runnable project by following our tutorial.

Connect to MongoDB Atlas

You can use the following connection snippet to test your connection to your MongoDB deployment on Atlas:

#include <mongoc/mongoc.h>
int main(void) {
    mongoc_client_t *client = NULL;
    bson_error_t error = {0};
    mongoc_server_api_t *api = NULL;
    mongoc_database_t *database = NULL;
    bson_t *command = NULL;
    bson_t reply = BSON_INITIALIZER;
    int rc = 0;
    bool ok = true;
    // Initialize the MongoDB C Driver.
    mongoc_init();
    client = mongoc_client_new("<connection string>");
    if (!client) {
        fprintf(stderr, "Failed to create a MongoDB client.\n");
        rc = 1;
        goto cleanup;
    }
    // Set the version of the Stable API on the client.
    api = mongoc_server_api_new(MONGOC_SERVER_API_V1);
    if (!api) {
        fprintf(stderr, "Failed to create a MongoDB server API.\n");
        rc = 1;
        goto cleanup;
    }
    ok = mongoc_client_set_server_api(client, api, &error);
    if (!ok) {
        fprintf(stderr, "error: %s\n", error.message);
        rc = 1;
        goto cleanup;
    }
    // Get a handle on the "admin" database.
    database = mongoc_client_get_database(client, "admin");
    if (!database) {
        fprintf(stderr, "Failed to get a MongoDB database handle.\n");
        rc = 1;
        goto cleanup;
    }
    // Ping the database.
    command = BCON_NEW("ping", BCON_INT32(1));
    ok = mongoc_database_command_simple(
        database, command, NULL, &reply, &error
    );
    if (!ok) {
        fprintf(stderr, "error: %s\n", error.message);
        rc = 1;
        goto cleanup;
    }
    bson_destroy(&reply);
    printf("Pinged your deployment. You successfully connected to MongoDB!\n");
// Perform cleanup.
cleanup:
    bson_destroy(command);
    mongoc_database_destroy(database);
    mongoc_server_api_destroy(api);
    mongoc_client_destroy(client);
    mongoc_cleanup();
    return rc;
}

This connection snippet uses the Stable API feature. You can access this feature when connecting to MongoDB Server v5.0 and later and using the C driver v1.18 and later.

When you use this feature, you can update your driver or server without worrying about backward compatibility issues with any commands covered by the Stable API.

Note

Starting from February 2022, the Versioned API is known as the Stable API. All concepts and features remain the same with this naming change.

Connect to MongoDB Atlas Without the Stable API

If you are using a version of MongoDB or the driver that lacks support for the Stable API, you can use the following code snippet to test your connection to your MongoDB deployment on Atlas:

#include <mongoc/mongoc.h>
int main(void) {
    mongoc_client_t *client = NULL;
    bson_error_t error = {0};
    mongoc_database_t *database = NULL;
    bson_t *command = NULL;
    bson_t reply = BSON_INITIALIZER;
    int rc = 0;
    bool ok = true;
    // Initialize the MongoDB C Driver.
    mongoc_init();
    client = mongoc_client_new("<connection string>");
    if (!client) {
        fprintf(stderr, "Failed to create a MongoDB client.\n");
        rc = 1;
        goto cleanup;
    }
    // Get a handle on the "admin" database.
    database = mongoc_client_get_database(client, "admin");
    if (!database) {
        fprintf(stderr, "Failed to get a MongoDB database handle.\n");
        rc = 1;
        goto cleanup;
    }
    // Ping the database.
    command = BCON_NEW("ping", BCON_INT32(1));
    ok = mongoc_database_command_simple(
        database, command, NULL, &reply, &error
    );
    if (!ok) {
        fprintf(stderr, "error: %s\n", error.message);
        rc = 1;
        goto cleanup;
    }
    bson_destroy(&reply);
    printf("Pinged your deployment. You successfully connected to MongoDB!\n");
// Perform cleanup.
cleanup:
    bson_destroy(command);
    mongoc_database_destroy(database);
    mongoc_client_destroy(client);
    mongoc_cleanup();
    return rc;
}

Compatibility

To learn about the versions of the MongoDB Server and the C language that are compatible with each version of the C driver, see the Compatibility page.

How To Get Help

Ask for help in the MongoDB Stack Overflow page or in the MongoDB Reddit community.
Visit our Support Channels.
File a bug or feature request on JIRA.

Back

Asynchronous C Driver: Public Preview