How can I handle migration from group to supergroup in telethon?

Question

I asked the question in #telethon telegram group, but don't got adequate answer. So, I got "code" for supporting migrations:

@client.on(events.Raw(types.UpdateNewChannelMessage))
async def migrate_event(event: types.UpdateNewChannelMessage):
    if event.message:
        if isinstance(event.message.action, types.MessageActionChannelMigrateFrom):
            was_chat_id = -1 * event.message.action.chat_id
            new_id = int('-100' + str(event.message.to_id.channel_id))
            raise events.StopPropagation

But it doesn't work when I change group permissions or permission of certain user (for eg transfer it to admin rights). I just get something like that:

UpdateChatParticipants(participants=ChatParticipants(chat_id=496384744, participants=[ChatParticipant(user_id=849120097, inviter_id=382775249, date=datetime.datetime(2020, 8, 18, 8, 28, 30, tzinfo=datetime.timezone.utc)), ChatParticipant(user_id=1038400746, inviter_id=382775249, date=datetime.datetime(2020, 8, 18, 8, 28, 30, tzinfo=datetime.timezone.utc)), ChatParticipantCreator(user_id=382775249)], version=1))

When listening to raw events:

@client.on(events.Raw)
async def migrate_event(event):
    print(event)
    print(event.message.action)

I just quite don't get that, I though it's because of older Telethon version (1.12) since newer Telethon versions are getting layer changes (so other definitions are built in setup.py on install) but I see it's different issue. I probably don't know how to code that properly and I miss some knowledge.

So, any idea how to handle it correctly?

Answer 1

The proposed code is working, you simply need to do something with the values...

from telethon import TelegramClient, events, types
...
@client.on(events.Raw(types.UpdateNewChannelMessage))
async def migrate_event(event: types.UpdateNewChannelMessage):
    """
    event new incoming message, filtered by MessageActionChannelMigrateFrom

    :param param1: event is the message object, types type of  action
    """
    if event.message:
        if event.message.action is not None:
            print('=========== Chat Action  ===============')
            if isinstance(event.message.action, types.MessageActionChannelMigrateFrom):
                was_chat_id = -1 * event.message.action.chat_id
                new_id = int('-100' + str(event.message.to_id.channel_id))
                print('############ CHAT MIGRATION ############')
                print('From_id: ' + str(was_chat_id) + 'To_id: ' + str(new_id))

This should print a message on every chat event and detect migrate to supergroup etc. and print old and new ID.

To get other actions you have to filter and process them also...