An example of an interface for using redis as a cache

redis_cache.py

import redis
import logging


def create_logger(logger_name):
    logger = logging.getLogger(logger_name)
    return logger


class BatchDateCache:
    BATCH_DATE_PREFIX = 'batch_date:'
    BATCH_DATE_TTL_SEC = 24 * 60 * 60  # destroy record after 24 hours (TTL)

    HOST = '127.0.0.10'
    PORT = 6379
    DB = 1

    def __init__(self, context):
        super().__init__()
        self.logger = create_logger(type(self).__name__)
        self.context = context
        redis_connection_pool = redis.ConnectionPool(host=self.HOST, port=self.PORT, db=self.DB)
        self.redis = redis.Redis(connection_pool=redis_connection_pool)

    def add_batch_date(self, assignment_id: str, batch_date: str) -> None:
        """
        The method sets a batch_date to the assignment_id
        if it does not already exist in the cache
        :param assignment_id: e.g. "2147483647"
        :param batch_date: e.g. "21/01/18"
        :return: None
        """
        self.logger.debug("Adding a batch_date %s to the assignment id %s", batch_date, assignment_id)
        key = '{}{}'.format(self.BATCH_DATE_PREFIX, assignment_id)
        assignment_exist = self.redis.exists(key)
        if assignment_exist:
            self.logger.error("Assignment id %s already exists in the batch date cache", assignment_id)
            return
        self.redis.set(key, batch_date, ex=self.BATCH_DATE_TTL_SEC)

    def get_batch_date(self, assignment_id: str, del_after: bool=False) -> str or None:
        """
        The method returns a batch date for the assignment_id
        and can remove the record from the cache after getting a value
        :param assignment_id: e.g. "2147483647"
        :param del_after: flag to remove the assignment_id from the cache after getting a batch date
        :return: a batch date for the assignment_id or None
        """
        self.logger.debug("Getting a batch_date for the assignment id %s", assignment_id)
        key = '{}{}'.format(self.BATCH_DATE_PREFIX, assignment_id)
        batch_date = self.redis.get(key)
        if not batch_date:
            self.logger.error("The key %s does not exist in the batch date cache", key)
            return
        if del_after:
            self._del_assignment(key)
        return batch_date.decode('utf-8')

    def _del_assignment(self, key: str) -> None:
        self.redis.delete(key)
        self.logger.debug("The key %s was deleted from the batch date cache", key)

    def purge(self) -> None:
        self.logger.info("Clearing the batch date cache for assignment ids")
        for key in self.redis.keys('{}*'.format(self.BATCH_DATE_PREFIX)):
            self.redis.delete(key)