cic-stack/apps/cic-ussd/cic_ussd/tasks/ussd.py

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2021-02-06 16:13:47 +01:00
# standard imports
import json
from datetime import timedelta
# third party imports
import celery
from celery.utils.log import get_logger
# local imports
from cic_ussd.db.models.base import SessionBase
from cic_ussd.db.models.ussd_session import UssdSession
from cic_ussd.error import SessionNotFoundError
from cic_ussd.session.ussd_session import UssdSession as InMemoryUssdSession
celery_app = celery.current_app
logg = get_logger(__file__)
@celery_app.task
def persist_session_to_db(external_session_id: str):
"""
This task initiates the saving of the session object to the database and it's removal from the in-memory storage.
:param external_session_id: The session id of the session to be saved.
:type external_session_id: str.
:return: The representation of the newly created database object or en error message if session is not found.
:rtype: str.
:raises SessionNotFoundError: If the session object is not found in memory.
:raises VersionTooLowError: If the session's version doesn't match the latest version.
"""
# create session
session = SessionBase.create_session()
# get ussd session in redis cache
in_memory_session = InMemoryUssdSession.redis_cache.get(external_session_id)
# process persistence to db
if in_memory_session:
in_memory_session = json.loads(in_memory_session)
in_db_ussd_session = session.query(UssdSession).filter_by(external_session_id=external_session_id).first()
if in_db_ussd_session:
in_db_ussd_session.update(
session=session,
user_input=in_memory_session.get('user_input'),
state=in_memory_session.get('state'),
version=in_memory_session.get('version'),
)
else:
in_db_ussd_session = UssdSession(
external_session_id=external_session_id,
service_code=in_memory_session.get('service_code'),
msisdn=in_memory_session.get('msisdn'),
user_input=in_memory_session.get('user_input'),
state=in_memory_session.get('state'),
version=in_memory_session.get('version'),
)
# handle the updating of session data for persistence to db
session_data = in_memory_session.get('session_data')
if session_data:
for key, value in session_data.items():
in_db_ussd_session.set_data(key=key, value=value, session=session)
session.add(in_db_ussd_session)
InMemoryUssdSession.redis_cache.expire(external_session_id, timedelta(minutes=1))
else:
session.close()
raise SessionNotFoundError('Session does not exist!')
session.commit()
session.close()