fix: fatal server error when creating room with channel (#1343)

[MohammedAnasNathani]

Description

Fixed a "Fatal Server Error" that occurred when creating a new room with a chat channel (e.g., "Chat" or "BigBlueButton" modules enabled).

The issue was caused because RoomConfigSerializer attempted to access the room.channel relationship inside the AuditLog creation step. Since the channel object was created but not manually attached to the room instance in memory, the serializer triggered a lazy database lookup inside the sync_to_async context, which likely failed or caused a race condition.

Issues

Closes #1343

Fix

• Explicitly attached the newly created channel object to room.channel in memory before calling the serializer.
• This ensures RoomConfigSerializer(room).data can serialize the channel ID without triggering additional database queries or failing.

Type of Change

• Bug fix (non-breaking change which fixes an issue)

Summary by Sourcery

Bug Fixes:

• Attach the newly created channel to the in-memory room instance so room configuration serialization during audit logging no longer triggers problematic lazy database access.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Ensures that when creating a room with an associated chat channel, the newly created Channel instance is attached to the in-memory Room object before audit logging/serialization, preventing lazy-loading-related fatal errors.

Sequence diagram for room creation with attached channel

sequenceDiagram
    participant Caller
    participant Service as EventService
    participant Room
    participant ChannelModel as Channel
    participant Serializer as RoomConfigSerializer
    participant AuditLogModel as AuditLog

    Caller->>Service: _create_room(data, with_channel=True, permission_preset, creator)
    Service->>Room: create Room instance
    activate Room
    Room-->>Service: room
    deactivate Room

    alt with_channel is True
        Service->>ChannelModel: objects.create(event_id=room.event_id, room=room)
        activate ChannelModel
        ChannelModel-->>Service: channel
        deactivate ChannelModel

        Service->>Room: set channel on room (room.channel = channel)
    end

    Service->>Serializer: RoomConfigSerializer(room)
    activate Serializer
    Serializer-->>Service: serialized room data (includes channel id)
    deactivate Serializer

    Service->>AuditLogModel: objects.create(event_id=room.event_id, data=serialized room data)
    activate AuditLogModel
    AuditLogModel-->>Service: audit_log
    deactivate AuditLogModel

    Service-->>Caller: room

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Class diagram for Room, Channel, AuditLog and RoomConfigSerializer

classDiagram
    class Room {
        int id
        int event_id
        Channel channel
    }

    class Channel {
        int id
        int event_id
        Room room
    }

    class AuditLog {
        int id
        int event_id
        string data
        datetime created_at
    }

    class RoomConfigSerializer {
        Room instance
        dict data
        RoomConfigSerializer(Room instance)
    }

    Room --> Channel : has_one
    Channel --> Room : belongs_to
    AuditLog --> Room : logs_changes_for
    RoomConfigSerializer --> Room : serializes
    RoomConfigSerializer ..> Channel : accesses_channel_via_room

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File-Level Changes

Change	Details	Files
Attach newly created channel instance to the in-memory room object to avoid lazy DB lookup during serialization/audit logging.	After creating a Channel when with_channel is True, assign the created channel instance to the room.channel attribute before any serialization or audit logging occurs	app/eventyay/base/services/event.py

Assessment against linked issues

Issue	Objective	Addressed	Explanation
#1343	Fix the backend bug causing a "Fatal Server Error" when creating a room in the video component so that room creation succeeds.	✅
#1343	Ensure that after attempting to create a room in the video component, the system no longer gets stuck in a continuous loading state (i.e., the request completes successfully).	✅

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[mariobehling]

Please showcase functionality by providing screenshots.

[Copilot]

Pull request overview

This PR fixes a fatal server error that occurred when creating a room with a chat channel enabled. The issue was caused by Django's ORM lazy-loading behavior when accessing the room.channel relationship during audit log serialization within an async context.

Key Changes:

• Explicitly assigns the newly created channel object to room.channel in memory after channel creation
• Ensures RoomConfigSerializer can access the channel without triggering additional database queries

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[MohammedAnasNathani]

@mariobehling Thanks for the review.

• Whitespace: I have fixed the trailing whitespace issue flagged by Copilot.
• Screenshot Request: Regarding the UI showcase: This PR addresses a Backend 500 Server Error (Crash) during the database transaction phase of room creation.

Since I am working in a cloud-based environment (Codespaces), I am currently blocked by a WebSocket restriction (Error 1006) which prevents the video frontend from rendering fully to capture a screenshot.
However, the fix is verified via code logic:

• Bug: The RoomConfigSerializer was triggering a RelatedObjectDoesNotExist error by trying to lazy-load room.channel inside an async transaction block.
• Fix: I explicitly pre-warm the room.channel relationship in memory (room.channel = channel) immediately after creation. This prevents the serializer from hitting the database again, resolving the crash.
  The logic ensures the transaction completes successfully instead of rolling back. I hope this technical verification suffices given the environment constraints.