259 lines
8.9 KiB
Python
259 lines
8.9 KiB
Python
# standard imports
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import logging
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from typing import Optional
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import json
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# external imports
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import celery
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from redis import Redis
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from sqlalchemy.orm.session import Session
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# local imports
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from cic_ussd.cache import Cache
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from cic_ussd.db.models.base import SessionBase
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from cic_ussd.db.models.ussd_session import UssdSession as DbUssdSession
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logg = logging.getLogger()
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class UssdSession:
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"""
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This class defines the USSD session object that is called whenever a user interacts with the system.
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:cvar store: The in-memory redis cache.
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:type store: Redis
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"""
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store: Redis = None
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def __init__(self,
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external_session_id: str,
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msisdn: str,
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service_code: str,
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state: str,
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user_input: str,
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data: Optional[dict] = None):
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"""
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This function is called whenever a USSD session object is created and saves the instance to a JSON DB.
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:param external_session_id: The Africa's Talking session ID.
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:type external_session_id: str.
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:param service_code: The USSD service code from which the user used to gain access to the system.
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:type service_code: str.
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:param msisdn: The user's phone number.
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:type msisdn: str.
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:param user_input: The data or choice the user has made while interacting with the system.
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:type user_input: str.
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:param state: The name of the USSD menu that the user was interacting with.
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:type state: str.
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:param data: Any additional data that was persisted during the user's interaction with the system.
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:type data: dict.
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"""
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self.data = data
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self.external_session_id = external_session_id
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self.msisdn = msisdn
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self.service_code = service_code
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self.state = state
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self.user_input = user_input
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session = self.store.get(external_session_id)
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if session:
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session = json.loads(session)
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self.version = session.get('version') + 1
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else:
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self.version = 1
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self.session = {
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'data': self.data,
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'external_session_id': self.external_session_id,
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'msisdn': self.msisdn,
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'service_code': self.service_code,
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'state': self.state,
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'user_input': self.user_input,
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'version': self.version
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}
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self.store.set(self.external_session_id, json.dumps(self.session))
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self.store.persist(self.external_session_id)
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def set_data(self, key: str, value: str) -> None:
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"""
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This function adds or updates data to the session data.
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:param key: The name used to identify the data.
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:type key: str.
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:param value: The actual data to be stored in the session data.
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:type value: str.
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"""
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if self.data is None:
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self.data = {}
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self.data[key] = value
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self.store.set(self.external_session_id, json.dumps(self.session))
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def get_data(self, key: str) -> Optional[str]:
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"""
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This function attempts to fetch data from the session data using the identifier for the specific data.
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:param key: The name used as the identifier for the specific data.
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:type key: str.
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:return: This function returns the queried data if found, else it doesn't return any value.
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:rtype: str.
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"""
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if self.data is not None:
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return self.data.get(key)
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else:
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return None
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def to_json(self):
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""" This function serializes the in memory ussd session object to a JSON object
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:return: A JSON object of a ussd session in memory
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:rtype: dict
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"""
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return {
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"data": self.data,
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"external_session_id": self.external_session_id,
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"msisdn": self.msisdn,
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"user_input": self.user_input,
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"service_code": self.service_code,
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"state": self.state,
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"version": self.version
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}
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def create_ussd_session(
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state: str,
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external_session_id: str,
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msisdn: str,
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service_code: str,
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user_input: str,
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data: Optional[dict] = None) -> UssdSession:
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"""
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:param state:
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:type state:
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:param external_session_id:
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:type external_session_id:
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:param msisdn:
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:type msisdn:
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:param service_code:
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:type service_code:
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:param user_input:
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:type user_input:
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:param data:
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:type data:
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:return:
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:rtype:
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"""
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return UssdSession(external_session_id=external_session_id,
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msisdn=msisdn,
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user_input=user_input,
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state=state,
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service_code=service_code,
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data=data
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)
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def update_ussd_session(ussd_session: UssdSession,
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user_input: str,
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state: str,
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data: Optional[dict] = None) -> UssdSession:
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""""""
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if data is None:
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data = ussd_session.data
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return UssdSession(
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external_session_id=ussd_session.external_session_id,
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msisdn=ussd_session.msisdn,
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user_input=user_input,
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state=state,
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service_code=ussd_session.service_code,
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data=data
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)
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def create_or_update_session(external_session_id: str,
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msisdn: str,
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service_code: str,
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user_input: str,
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state: str,
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session,
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data: Optional[dict] = None) -> UssdSession:
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"""
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:param external_session_id:
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:type external_session_id:
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:param msisdn:
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:type msisdn:
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:param service_code:
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:type service_code:
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:param user_input:
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:type user_input:
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:param state:
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:type state:
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:param session:
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:type session:
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:param data:
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:type data:
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:return:
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:rtype:
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"""
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session = SessionBase.bind_session(session=session)
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existing_ussd_session = session.query(DbUssdSession).filter_by(
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external_session_id=external_session_id).first()
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if existing_ussd_session:
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ussd_session = update_ussd_session(ussd_session=existing_ussd_session,
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state=state,
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user_input=user_input,
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data=data
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)
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else:
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ussd_session = create_ussd_session(external_session_id=external_session_id,
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msisdn=msisdn,
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service_code=service_code,
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user_input=user_input,
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state=state,
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data=data
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)
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SessionBase.release_session(session=session)
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return ussd_session
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def persist_ussd_session(external_session_id: str, queue: Optional[str]):
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"""This function asynchronously retrieves a cached ussd session object matching an external ussd session id and adds
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it to persistent storage.
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:param external_session_id: Session id value provided by ussd service provided.
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:type external_session_id: str
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:param queue: Name of worker queue to submit tasks to.
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:type queue: str
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"""
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s_persist_ussd_session = celery.signature(
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'cic_ussd.tasks.ussd_session.persist_session_to_db',
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[external_session_id],
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queue=queue
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)
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s_persist_ussd_session.apply_async()
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def save_session_data(queue: Optional[str], session: Session, data: dict, ussd_session: dict):
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"""This function is stores information to the session data attribute of a cached ussd session object.
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:param data: A dictionary containing data for a specific ussd session in redis that needs to be saved
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temporarily.
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:type data: dict
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:param queue: The queue on which the celery task should run.
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:type queue: str
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:param session: Database session object.
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:type session: Session
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:param ussd_session: A ussd session passed to the state machine.
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:type ussd_session: UssdSession
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"""
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cache = Cache.store
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external_session_id = ussd_session.get('external_session_id')
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existing_session_data = ussd_session.get('data')
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if existing_session_data:
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data = {**existing_session_data, **data}
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in_redis_ussd_session = cache.get(external_session_id)
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in_redis_ussd_session = json.loads(in_redis_ussd_session)
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create_or_update_session(
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external_session_id=external_session_id,
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msisdn=in_redis_ussd_session.get('msisdn'),
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service_code=in_redis_ussd_session.get('service_code'),
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user_input=in_redis_ussd_session.get('user_input'),
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state=in_redis_ussd_session.get('state'),
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session=session,
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data=data
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)
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persist_ussd_session(external_session_id=external_session_id, queue=queue)
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