Add a friendly method to react to messages (#3681)

telethon/_client/messages.py

@@ -747,3 +747,44 @@ async def _pin(self, entity, message, *, unpin, notify=False, pm_oneside=False):
 
     # Pinning a message that doesn't exist would RPC-error earlier
     return self._get_response_message(request, result, entity)
+
+async def send_reaction(
+    self: 'TelegramClient',
+    entity: 'hints.EntityLike',
+    message: 'hints.MessageIDLike',
+    reaction: typing.Optional[str] = None,
+    big: bool = False
+):
+    message = utils.get_message_id(message) or 0
+    if not reaction:
+        get_default_request = _tl.fn.help.GetAppConfig()
+        app_config = await self(get_default_request)
+        reaction = (
+            next(
+                (
+                    y for y in app_config.value
+                    if "reactions_default" in y.key
+                )
+            )
+        ).value.value
+    request = _tl.fn.messages.SendReaction(
+        big=big,
+        peer=entity,
+        msg_id=message,
+        reaction=reaction
+    )
+    result = await self(request)
+    for update in result.updates:
+        if isinstance(update, _tl.UpdateMessageReactions):
+            return update.reactions
+        if isinstance(update, _tl.UpdateEditMessage):
+            return update.message.reactions
+
+async def set_quick_reaction(
+    self: 'TelegramClient',
+    reaction: str
+):
+    request = _tl.fn.messages.SetDefaultReaction(
+        reaction=reaction
+    )
+    return await self(request)

telethon/types/_custom/message.py

@@ -1251,6 +1251,19 @@ class Message(ChatGetter, SenderGetter):
         return await self._client.unpin_message(
             await self.get_input_chat(), self.id)
 
+    async def react(self, reaction=None):
+        """
+        Reacts on the given message. Shorthand for
+        `telethon.client.messages.MessageMethods.send_reaction`
+        with both ``entity`` and ``message`` already set.
+        """
+        if self._client:
+            return await self._client.send_reaction(
+                await self.get_input_chat(),
+                self.id,
+                reaction
+            )
+
     # endregion Public Methods
 
     # region Private Methods