From 4b9b77614fcc1ddaa750652abdec11969f25e3bd Mon Sep 17 00:00:00 2001
From: Lonami Exo <totufals@hotmail.com>
Date: Fri, 4 Jan 2019 11:13:13 +0100
Subject: [PATCH] Support answering inline queries with empty text (#1053)

---
 telethon/tl/custom/inlinebuilder.py | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/telethon/tl/custom/inlinebuilder.py b/telethon/tl/custom/inlinebuilder.py
index a03338bb..db0a06cb 100644
--- a/telethon/tl/custom/inlinebuilder.py
+++ b/telethon/tl/custom/inlinebuilder.py
@@ -125,8 +125,11 @@ class InlineBuilder:
             type='photo',
             photo=fh,
             send_message=await self._message(
-                text=text, parse_mode=parse_mode, link_preview=link_preview,
-                geo=geo, period=period,
+                text=text or '',
+                parse_mode=parse_mode,
+                link_preview=link_preview,
+                geo=geo,
+                period=period,
                 contact=contact,
                 game=game,
                 buttons=buttons
@@ -200,8 +203,14 @@ class InlineBuilder:
             type=type,
             document=fh,
             send_message=await self._message(
-                text=text, parse_mode=parse_mode, link_preview=link_preview,
-                geo=geo, period=period,
+                # Empty string for text if there's media but text is None.
+                # We may want to display a document but send text; however
+                # default to sending the media (without text, i.e. stickers).
+                text=text or '',
+                parse_mode=parse_mode,
+                link_preview=link_preview,
+                geo=geo,
+                period=period,
                 contact=contact,
                 game=game,
                 buttons=buttons
@@ -247,8 +256,9 @@ class InlineBuilder:
             text=None, parse_mode=(), link_preview=True,
             geo=None, period=60, contact=None, game=False, buttons=None
     ):
-        args = (text, geo, contact, game)
-        if sum(1 for x in args if x) != 1:
+        # Empty strings are valid but false-y; if they're empty use dummy '\0'
+        args = ('\0' if text == '' else text, geo, contact, game)
+        if sum(1 for x in args if x is not None and x is not False) != 1:
             raise ValueError(
                 'Must set exactly one of text, geo, contact or game (set {})'
                 .format(', '.join(x[0] for x in zip(
@@ -256,7 +266,10 @@ class InlineBuilder:
             )
 
         markup = self._client.build_reply_markup(buttons, inline_only=True)
-        if text:
+        if text is not None:
+            if not text:  # Automatic media on empty string, like stickers
+                return types.InputBotInlineMessageMediaAuto('')
+
             text, msg_entities = await self._client._parse_message_text(
                 text, parse_mode
             )