A simple C example to insert a sub document in MongoDB.

insertSubDocumentExample.c

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

int main (int   argc, char *argv[])
{
    mongoc_client_t *client;
    mongoc_collection_t *collection;
    mongoc_cursor_t *cursor;
    bson_error_t error;
    bson_oid_t oid;
    bson_t *doc;

    mongoc_init ();

    client = mongoc_client_new ("mongodb://localhost:27017/");
    collection = mongoc_client_get_collection (client, "test", "test");

    doc = bson_new ();
    bson_t child;
    BSON_APPEND_DOCUMENT_BEGIN(doc, "students", &child);
    BSON_APPEND_UTF8(&child, "name", "Oconnor");
    BSON_APPEND_UTF8(&child, "status", "true");
    BSON_APPEND_INT32(&child, "employee", 100);
    bson_append_document_end(doc, &child);

    if (!mongoc_collection_insert (collection, MONGOC_INSERT_NONE, doc, NULL, &error)) {
        printf ("%s\n", error.message);
    }

    bson_destroy (doc);
    mongoc_collection_destroy (collection);
    mongoc_client_destroy (client);

    return 0;
}