Get a record from the database with the id field matching `obj_id`.

def get_instance(self, collection, obj_id, **kwargs):
        """Get a record from the database with the id field matching `obj_id`.
        """
        logging.info("Getting single record")
        try:
            obj_id = ObjectId(obj_id)
        except InvalidId:
            logging.error("Invalid ObjectId: {}".format(obj_id))
            return {}
        projection = kwargs.get('projection', {})
        projection = None if len(projection) < 1 else projection
        query = kwargs.get('query', {})
        query.update({'_id': obj_id})
        logging.debug("Query: {}".format(query))
        logging.debug("Projection: {}".format(projection))
        record = self.db[collection].find_one(query, projection)
        return record