222 lines
6.8 KiB
ReStructuredText
222 lines
6.8 KiB
ReStructuredText
More on Updates
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===============
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Here we'll show some advanced usages when working with `update handlers`_ and `filters`_.
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Handler Groups
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--------------
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If you register handlers with overlapping (conflicting) filters, only the first one is executed and any other handler
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will be ignored. This is intended by design.
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In order to handle the very same update more than once, you have to register your handler in a different dispatching
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group. Dispatching groups hold one or more handlers and are processed sequentially, they are identified by a number
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(number 0 being the default) and sorted, that is, a lower group number has a higher priority:
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For example, take these two handlers:
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.. code-block:: python
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:emphasize-lines: 1, 6
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@app.on_message(Filters.text | Filters.sticker)
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def text_or_sticker(client, message):
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print("Text or Sticker")
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@app.on_message(Filters.text)
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def just_text(client, message):
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print("Just Text")
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Here, ``just_text`` is never executed because ``text_or_sticker``, which has been registered first, already handles
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texts (``Filters.text`` is shared and conflicting). To enable it, register the function using a different group:
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.. code-block:: python
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@app.on_message(Filters.text, group=1)
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def just_text(client, message):
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print("Just Text")
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Or, if you want ``just_text`` to be fired *before* ``text_or_sticker`` (note ``-1``, which is less than ``0``):
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.. code-block:: python
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@app.on_message(Filters.text, group=-1)
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def just_text(client, message):
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print("Just Text")
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With :meth:`add_handler() <pyrogram.Client.add_handler>` (without decorators) the same can be achieved with:
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.. code-block:: python
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app.add_handler(MessageHandler(just_text, Filters.text), -1)
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Update propagation
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------------------
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Registering multiple handlers, each in a different group, becomes useful when you want to handle the same update more
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than once. Any incoming update will be sequentially processed by all of your registered functions by respecting the
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groups priority policy described above. Even in case any handler raises an unhandled exception, Pyrogram will still
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continue to propagate the same update to the next groups until all the handlers are done. Example:
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.. code-block:: python
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@app.on_message(Filters.private)
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def _(client, message):
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print(0)
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@app.on_message(Filters.private, group=1)
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def _(client, message):
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raise Exception("Unhandled exception!") # Simulate an unhandled exception
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@app.on_message(Filters.private, group=2)
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def _(client, message):
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print(2)
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All these handlers will handle the same kind of messages, that are, messages sent or received in private chats.
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The output for each incoming update will therefore be:
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.. code-block:: text
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0
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Exception: Unhandled exception!
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2
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Stop Propagation
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^^^^^^^^^^^^^^^^
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In order to prevent further propagation of an update in the dispatching phase, you can do *one* of the following:
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- Call the update's bound-method ``.stop_propagation()`` (preferred way).
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- Manually ``raise StopPropagation`` exception (more suitable for raw updates only).
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.. note::
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Internally, the propagation is stopped by handling a custom exception. ``.stop_propagation()`` is just an elegant
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and intuitive way to ``raise StopPropagation``; this also means that any code coming *after* calling the method
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won't be executed as your function just raised an exception to signal the dispatcher not to propagate the
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update anymore.
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Example with ``stop_propagation()``:
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.. code-block:: python
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@app.on_message(Filters.private)
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def _(client, message):
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print(0)
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@app.on_message(Filters.private, group=1)
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def _(client, message):
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print(1)
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message.stop_propagation()
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@app.on_message(Filters.private, group=2)
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def _(client, message):
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print(2)
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Example with ``raise StopPropagation``:
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.. code-block:: python
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from pyrogram import StopPropagation
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@app.on_message(Filters.private)
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def _(client, message):
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print(0)
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@app.on_message(Filters.private, group=1)
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def _(client, message):
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print(1)
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raise StopPropagation
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@app.on_message(Filters.private, group=2)
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def _(client, message):
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print(2)
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Each handler is registered in a different group, but the handler in group number 2 will never be executed because the
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propagation was stopped earlier. The output of both (equivalent) examples will be:
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.. code-block:: text
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0
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1
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Continue Propagation
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^^^^^^^^^^^^^^^^^^^^
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As opposed to `stopping the update propagation <#stop-propagation>`_ and also as an alternative to the
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`handler groups <#handler-groups>`_, you can signal the internal dispatcher to continue the update propagation within
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**the same group** despite having conflicting filters in the next registered handler. This allows you to register
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multiple handlers with overlapping filters in the same group; to let the dispatcher process the next handler you can do
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*one* of the following in each handler you want to grant permission to continue:
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- Call the update's bound-method ``.continue_propagation()`` (preferred way).
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- Manually ``raise ContinuePropagation`` exception (more suitable for raw updates only).
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.. note::
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Internally, the propagation is continued by handling a custom exception. ``.continue_propagation()`` is just an
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elegant and intuitive way to ``raise ContinuePropagation``; this also means that any code coming *after* calling the
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method won't be executed as your function just raised an exception to signal the dispatcher to continue with the
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next available handler.
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Example with ``continue_propagation()``:
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.. code-block:: python
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@app.on_message(Filters.private)
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def _(client, message):
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print(0)
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message.continue_propagation()
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@app.on_message(Filters.private)
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def _(client, message):
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print(1)
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message.continue_propagation()
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@app.on_message(Filters.private)
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def _(client, message):
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print(2)
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Example with ``raise ContinuePropagation``:
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.. code-block:: python
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from pyrogram import ContinuePropagation
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@app.on_message(Filters.private)
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def _(client, message):
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print(0)
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raise ContinuePropagation
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@app.on_message(Filters.private)
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def _(client, message):
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print(1)
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raise ContinuePropagation
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@app.on_message(Filters.private)
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def _(client, message):
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print(2)
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Three handlers are registered in the same group, and all of them will be executed because the propagation was continued
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in each handler (except in the last one, where is useless to do so since there is no more handlers after).
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The output of both (equivalent) examples will be:
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.. code-block:: text
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0
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1
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2
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.. _`update handlers`: UpdateHandling.html
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.. _`filters`: UsingFilters.html |