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