mongoc_bulk_operation_update_one()
Synopsis
void
mongoc_bulk_operation_update_one (mongoc_bulk_operation_t *bulk,
                                  const bson_t            *selector,
                                  const bson_t            *document,
                                  bool                     upsert);This function queues an update as part of a bulk operation. It will only modify a single document on the MongoDB server. This function does not execute the operation. To execute the entirety of the bulk operation call mongoc_bulk_operation_execute().
document must only contain fields whose key starts with $. See the update document specification for more details.