'Converts list of objects from query to JSON'

def get_values_json(self, lst, list_columns):

    result = []
    for item in self.get_values(lst, list_columns):
        for (key, value) in list(item.items()):
            if (isinstance(value, datetime.datetime) or isinstance(value, datetime.date)):
                value = value.isoformat()
                item[key] = value
            if isinstance(value, list):
                item[key] = [str(v) for v in value]
        result.append(item)
    return result
