Fix(storage): correct pipeline usage of RedisStorage to retrieve event_id and prevent type errors

[Jimmy-web169]

Description

What did this PR change

• Refactored the Redis pipeline usage to execute INCR before using its result as event_id.
• Changed from single pipeline chain to a two-step execution:
  • First pipeline: INCR command to increment event counter and retrieve the new event_id.
  • Second pipeline: SETEX with the correctly retrieved event_id.

Why was this change necessary

The original implementation misused the Redis pipeline API by directly assigning the result of pipe.incr(...) to event_id.

However, in Redis-py, calling pipe.incr(...) does not immediately execute and instead queues the command, returning the pipeline object itself. This led to:

• event_id being a Pipeline object, not an integer.
• Consequently, building the Redis key resulted in:

"event:my_channel:<redis.client.Pipeline object at 0x7f8b8c0d5f40>"

-This also causing the following error when running django setting with "django_eventstream.storage.RedisStorage":

TypeError: unsupported operand type(s) for -: 'Pipeline' and 'int'

Notes

• File changed: django_eventstream/storage.py
• This is currently implemented as a workaround, splitting the pipeline into two executions to ensure we have a concrete event_id before using it in the second operation.
• Future improvements might include to keep it atomic in a single transaction if needed.