Telethon/readthedocs/extra/basic/entities.rst

.. _entities:

=========================
Users, Chats and Channels
=========================


Introduction
************

The library widely uses the concept of "entities". An entity will refer
to any :tl:`User`, :tl:`Chat` or :tl:`Channel` object that the API may return
in response to certain methods, such as :tl:`GetUsersRequest`.

.. note::

    When something "entity-like" is required, it means that you need to
    provide something that can be turned into an entity. These things include,
    but are not limited to, usernames, exact titles, IDs, :tl:`Peer` objects,
    or even entire :tl:`User`, :tl:`Chat` and :tl:`Channel` objects and even
    phone numbers from people you have in your contacts.

    To "encounter" an ID, you would have to "find it" like you would in the
    normal app. If the peer is in your dialogs, you would need to
    `client.get_dialogs() <telethon.client.dialogs.DialogMethods.get_dialogs>`.
    If the peer is someone in a group, you would similarly
    `client.get_participants(group) <telethon.client.chats.ChatMethods.get_participants>`.

    Once you have encountered an ID, the library will (by default) have saved
    their ``access_hash`` for you, which is needed to invoke most methods.
    This is why sometimes you might encounter this error when working with
    the library. You should ``except ValueError`` and run code that you know
    should work to find the entity.


Getting entities
****************

Through the use of the :ref:`sessions`, the library will automatically
remember the ID and hash pair, along with some extra information, so
you're able to just do this:

    .. code-block:: python

        # Dialogs are the "conversations you have open".
        # This method returns a list of Dialog, which
        # has the .entity attribute and other information.
        dialogs = client.get_dialogs()

        # All of these work and do the same.
        lonami = client.get_entity('lonami')
        lonami = client.get_entity('t.me/lonami')
        lonami = client.get_entity('https://telegram.dog/lonami')

        # Other kind of entities.
        channel = client.get_entity('telegram.me/joinchat/AAAAAEkk2WdoDrB4-Q8-gg')
        contact = client.get_entity('+34xxxxxxxxx')
        friend  = client.get_entity(friend_id)

        # Getting entities through their ID (User, Chat or Channel)
        entity = client.get_entity(some_id)

        # You can be more explicit about the type for said ID by wrapping
        # it inside a Peer instance. This is recommended but not necessary.
        from telethon.tl.types import PeerUser, PeerChat, PeerChannel

        my_user    = client.get_entity(PeerUser(some_id))
        my_chat    = client.get_entity(PeerChat(some_id))
        my_channel = client.get_entity(PeerChannel(some_id))


All methods in the :ref:`telegram-client` call `.get_input_entity()
<telethon.client.users.UserMethods.get_input_entity>` prior
to sending the requst to save you from the hassle of doing so manually.
That way, convenience calls such as `client.send_message('lonami', 'hi!')
<telethon.client.messages.MessageMethods.send_message>`
become possible.

Every entity the library encounters (in any response to any call) will by
default be cached in the ``.session`` file (an SQLite database), to avoid
performing unnecessary API calls. If the entity cannot be found, additonal
calls like :tl:`ResolveUsernameRequest` or :tl:`GetContactsRequest` may be
made to obtain the required information.


Entities vs. Input Entities
***************************

.. note::

    Don't worry if you don't understand this section, just remember some
    of the details listed here are important. When you're calling a method,
    don't call `client.get_entity() <telethon.client.users.UserMethods.get_entity>`
    beforehand, just use the username or phone, or the entity retrieved by
    other means like `client.get_dialogs()
    <telethon.client.dialogs.DialogMethods.get_dialogs>`.


On top of the normal types, the API also make use of what they call their
``Input*`` versions of objects. The input version of an entity (e.g.
:tl:`InputPeerUser`, :tl:`InputChat`, etc.) only contains the minimum
information that's required from Telegram to be able to identify
who you're referring to: a :tl:`Peer`'s **ID** and **hash**.

This ID/hash pair is unique per user, so if you use the pair given by another
user **or bot** it will **not** work.

To save *even more* bandwidth, the API also makes use of the :tl:`Peer`
versions, which just have an ID. This serves to identify them, but
peers alone are not enough to use them. You need to know their hash
before you can "use them".

As we just mentioned, API calls don't need to know the whole information
about the entities, only their ID and hash. For this reason, another method,
`client.get_input_entity() <telethon.client.users.UserMethods.get_input_entity>`
is available. This will always use the cache while possible, making zero API
calls most of the time. When a request is made, if you provided the full
entity, e.g. an :tl:`User`, the library will convert it to the required
:tl:`InputPeer` automatically for you.

**You should always favour**
`client.get_input_entity() <telethon.client.users.UserMethods.get_input_entity>`
**over**
`client.get_entity() <telethon.client.users.UserMethods.get_entity>`
for this reason! Calling the latter will always make an API call to get
the most recent information about said entity, but invoking requests don't
need this information, just the :tl:`InputPeer`. Only use
`client.get_entity() <telethon.client.users.UserMethods.get_entity>`
if you need to get actual information, like the username, name, title, etc.
of the entity.

To further simplify the workflow, since the version ``0.16.2`` of the
library, the raw requests you make to the API are also able to call
`client.get_input_entity() <telethon.client.users.UserMethods.get_input_entity>`
wherever needed, so you can even do things like:

    .. code-block:: python

        client(SendMessageRequest('username', 'hello'))

The library will call the ``.resolve()`` method of the request, which will
resolve ``'username'`` with the appropriated :tl:`InputPeer`. Don't worry if
you don't get this yet, but remember some of the details here are important.


Full entities
*************

In addition to :tl:`PeerUser`, :tl:`InputPeerUser`, :tl:`User` (and its
variants for chats and channels), there is also the concept of :tl:`UserFull`.

This full variant has additional information such as whether the user is
blocked, its notification settings, the bio or about of the user, etc.

There is also :tl:`messages.ChatFull` which is the equivalent of full entities
for chats and channels, with also the about section of the channel. Note that
the ``users`` field only contains bots for the channel (so that clients can
suggest commands to use).

You can get both of these by invoking :tl:`GetFullUser`, :tl:`GetFullChat`
and :tl:`GetFullChannel` respectively.