Expand documentation on using the raw API

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Lonami Exo 2023-03-11 12:45:06 +01:00
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@ -10,13 +10,20 @@ The Full API
methods listed on :ref:`client-ref` unless you have a better reason
not to, like a method not existing or you wanting more control.
.. contents::
Introduction
============
The :ref:`telethon-client` doesn't offer a method for every single request
the Telegram API supports. However, it's very simple to *call* or *invoke*
any request. Whenever you need something, don't forget to `check the documentation`_
and look for the `method you need`_. There you can go through a sorted list
of everything you can do.
any request defined in Telegram's API.
This section will teach you how to use what Telethon calls the `TL reference`_.
The linked page contains a list and a way to search through *all* types
generated from the definition of Telegram's API (in ``.tl`` file format,
hence the name). These types include requests and constructors.
.. note::
@ -25,10 +32,193 @@ of everything you can do.
as you type, and a "Copy import" button. If you like namespaces, you
can also do ``from telethon.tl import types, functions``. Both work.
Telegram makes these ``.tl`` files public, which other implementations, such
as Telethon, can also use to generate code. These files are versioned under
what's called "layers". ``.tl`` files consist of thousands of definitions,
and newer layers often add, change, or remove them. Each definition refers
to either a Remote Procedure Call (RPC) function, or a type (which the
`TL reference`_ calls "constructors", as they construct particular type
instances).
You should also refer to the documentation to see what the objects
(constructors) Telegram returns look like. Every constructor inherits
from a common type, and that's the reason for this distinction.
As such, the `TL reference`_ is a good place to go to learn about all possible
requests, types, and what they look like. If you're curious about what's been
changed between layers, you can refer to the `TL diff`_ site.
Navigating the TL reference
===========================
Functions
---------
"Functions" is the term used for the Remote Procedure Calls (RPC) that can be
sent to Telegram to ask it to perform something (e.g. "send message"). These
requests have an associated return type. These can be invoked ("called"):
.. code-block:: python
client = TelegramClient(...)
function_instance = SomeRequest(...)
# Invoke the request
returned_type = await client(function_instance)
Whenever you find the type for a function in the `TL reference`_, the page
will contain the following information:
* What type of account can use the method. This information is regenerated
from time to time (by attempting to invoke the function under both account
types and finding out where it fails). Some requests can only be used by
bot accounts, others by user accounts, and others by both.
* The TL definition. This helps you get a feel for the what the function
looks like. This is not Python code. It just contains the definition in
a concise manner.
* "Copy import" button. Does what it says: it will copy the necessary Python
code to import the function to your system's clipboard for easy access.
* Returns. The returned type. When you invoke the function, this is what the
result will be. It also includes which of the constructors can be returned
inline, to save you a click.
* Parameters. The parameters accepted by the function, including their type,
whether they expect a list, and whether they're optional.
* Known RPC errors. A best-effort list of known errors the request may cause.
This list is not complete and may be out of date, but should provide an
overview of what could go wrong.
* Example. Autogenerated example, showcasing how you may want to call it.
Bear in mind that this is *autogenerated*. It may be spitting out non-sense.
The goal of this example is not to show you everything you can do with the
request, only to give you a feel for what it looks like to use it.
It is very important to click through the links and navigate to get the full
picture. A specific page will show you what the specific function returns and
needs as input parameters. But it may reference other types, so you need to
navigate to those to learn what those contain or need.
Types
-----
"Types" as understood by TL are not actually generated in Telethon.
They would be the "abstract base class" of the constructors, but since Python
is duck-typed, there is hardly any need to generate mostly unnecessary code.
The page for a type contains:
* Constructors. Every type will have one or more constructors. These
constructors *are* generated and can be immported and used.
* Requests returning this type. A helpful way to find out "what requests can
return this?". This is how you may learn what request you need to use to
obtain a particular instance of a type.
* Requests accepting this type as input. A helpful way to find out "what
requests can use this type as one of their input parameters?". This is how
you may learn where a type is used.
* Other types containing this type. A helpful way to find out "where else
does this type appear?". This is how you can walk back through nested
objects.
Constructors
------------
Constructors are used to create instances of a particular type, and are also
returned when invoking requests. You will have to create instances yourself
when invoking requests that need a particular type as input.
The page for a constructor contains:
* Belongs to. The parent type. This is a link back to the types page for the
specific constructor. It also contains the sibling constructors inline, to
save you a click.
* Members. Both the input parameters *and* fields the constructor contains.
Using the TL reference
======================
After you've found a request you want to send, a good start would be to simply
copy and paste the autogenerated example into your script. Then you can simply
tweak it to your needs.
If you want to do it from scratch, first, make sure to import the request into
your code (either using the "Copy import" button near the top, or by manually
spelling out the package under ``telethon.tl.functions.*``).
Then, start reading the parameters one by one. If the parameter cannot be
omitted, you **will** need to specify it, so make sure to spell it out as
an input parameter when constructing the request instance. Let's look at
`PingRequest`_ for example. First, we copy the import:
.. code-block:: python
from telethon.tl.functions import PingRequest
Then, we look at the parameters:
ping_id - long
A single parameter, and it's a long (a integer number with a large range of
values). It doesn't say it can be omitted, so we must provide it, like so:
.. code-block:: python
PingRequest(
ping_id=48641868471
)
(In this case, the ping ID is a random number. You often have to guess what
the parameter needs just by looking at the name.)
Now that we have our request, we can invoke it:
.. code-block:: python
response = await client(PingRequest(
ping_id=48641868471
))
To find out what ``response`` looks like, we can do as the autogenerated
example suggests and "stringify" the result as a pretty-printed string:
.. code-block:: python
print(result.stringify())
This will print out the following:
.. code-block:: python
Pong(
msg_id=781875678118,
ping_id=48641868471
)
Which is a very easy way to get a feel for a response. You should nearly
always print the stringified result, at least once, when trying out requests,
to get a feel for what the response may look like.
But of course, you don't need to do that. Without writing any code, you could
have navigated through the "Returns" link to learn ``PingRequest`` returns a
``Pong``, which only has one constructor, and the constructor has two members,
``msg_id`` and ``ping_id``.
If you wanted to create your own ``Pong``, you would use both members as input
parameters:
.. code-block:: python
my_pong = Pong(
msg_id=781875678118,
ping_id=48641868471
)
(Yes, constructing object instances can use the same code that ``.stringify``
would return!)
And if you wanted to access the ``msg_id`` member, you would simply access it
like any other attribute access in Python:
.. code-block:: python
print(response.msg_id)
Example walkthrough
===================
Say `client.send_message()
<telethon.client.messages.MessageMethods.send_message>` didn't exist,
@ -224,6 +414,7 @@ and still access the successful results:
# The second request failed.
second = e.exceptions[1]
.. _check the documentation: https://tl.telethon.dev
.. _method you need: https://tl.telethon.dev/methods/index.html
.. _TL reference: https://tl.telethon.dev
.. _TL diff: https://diff.telethon.dev
.. _PingRequest: https://tl.telethon.dev/methods/ping.html
.. _use the search: https://tl.telethon.dev/?q=message&redirect=no