The library comes with the
events module. Events are an abstraction
over what Telegram calls updates, and are meant to ease simple and common
usage when dealing with them, since there are many updates. If you’re looking
for the method reference, check telethon.events package, otherwise,
let’s dive in!
The library logs by default no output, and any exception that occurs
inside your handlers will be “hidden” from you to prevent the thread
from terminating (so it can still deliver events). You should enable
import logging; logging.basicConfig(level=logging.ERROR))
when working with events, at least the error level, to see if this is
happening so you can debug the error.
from telethon import TelegramClient, events client = TelegramClient(..., update_workers=1, spawn_read_thread=False) client.start() @client.on(events.NewMessage) def my_event_handler(event): if 'hello' in event.raw_text: event.reply('hi!') client.idle()
Not much, but there might be some things unclear. What does this code do?
from telethon import TelegramClient, events client = TelegramClient(..., update_workers=1, spawn_read_thread=False) client.start()
This is normal initialization (of course, pass session name, API ID and hash). Nothing we don’t know already.
This Python decorator will attach itself to the
definition, and basically means that on a
the callback function you’re about to define will be called:
def my_event_handler(event): if 'hello' in event.raw_text: event.reply('hi!')
NewMessage event occurs, and
'hello' is in the text of the
reply to the event with a
Finally, this tells the client that we’re done with our code, and want to listen for all these events to occur. Of course, you might want to do other things instead idling. For this refer to Update Modes.
NewMessage event has much more than what was shown. You can access
.sender of the message through that member, or even see if the message
.photo or a
.document (which you could download with
If you don’t want to
.reply as a reply, you can use the
method instead. Of course, there are more events such as
UserUpdate, and they’re all used in the same way. Simply add the
@client.on(events.XYZ) decorator on the top of your handler and you’re
done! The event that will be passed always is of type
NewMessage.Event), except for the
Raw event which just
.respond() are just wrappers around the
client.send_message() method which supports the
This means you can reply with a photo if you do
You can put the same event on many handlers, and even different events on the same handler. You can also have a handler work on only specific chats, for example:
import ast import random # Either a single item or a list of them will work for the chats. # You can also use the IDs, Peers, or even User/Chat/Channel objects. @client.on(events.NewMessage(chats=('TelethonChat', 'TelethonOffTopic'))) def normal_handler(event): if 'roll' in event.raw_text: event.reply(str(random.randint(1, 6))) # Similarly, you can use incoming=True for messages that you receive @client.on(events.NewMessage(chats='TelethonOffTopic', outgoing=True)) def admin_handler(event): if event.raw_text.startswith('eval'): expression = event.raw_text.replace('eval', '').strip() event.reply(str(ast.literal_eval(expression)))
You can pass one or more chats to the
chats parameter (as a list or tuple),
and only events from there will be processed. You can also specify whether you
want to handle incoming or outgoing messages (those you receive or those you
send). In this example, people can say
'roll' and you will reply with a
random number, while if you say
'eval 4+4', you will reply with the
solution. Try it!
If for any reason you can’t use the
@client.on syntax, don’t worry.
You can call
client.add_event_handler(callback, event) to achieve
the same effect.
Similar to that method, you also have
client.list_event_handlers() which do as they names indicate.
event type is optional in all methods and defaults to
for adding, and
None when removing (so all callbacks would be removed).
There might be cases when an event handler is supposed to be used solitary and
it makes no sense to process any other handlers in the chain. For this case,
it is possible to raise a
StopPropagation exception which will cause the
propagation of the update through your handlers to stop:
from telethon.events import StopPropagation @client.on(events.NewMessage) def _(event): # ... some conditions event.delete() # Other handlers won't have an event to work with raise StopPropagation @client.on(events.NewMessage) def _(event): # Will never be reached, because it is the second handler # in the chain. pass
Remember to check telethon.events package if you’re looking for the methods reference.