docs: filter against bot_id in listener middleware example (#1339)

Author: zimeg

docs/content/concepts/listener-middleware.md

@@ -11,11 +11,10 @@ If your listener middleware is a quite simple one, you can use a listener matche
 Refer to [the module document](https://tools.slack.dev/bolt-python/api-docs/slack_bolt/kwargs_injection/args.html) to learn the available listener arguments.
 
 ```python
-# Listener middleware which filters out messages with "bot_message" subtype
+# Listener middleware which filters out messages from a bot
 def no_bot_messages(message, next):
-    subtype = message.get("subtype")
-    if subtype != "bot_message":
-       next()
+    if "bot_id" not in message:
+        next()
 
 # This listener only receives messages from humans
 @app.event(event="message", middleware=[no_bot_messages])
@@ -24,10 +23,10 @@ def log_message(logger, event):
 
 # Listener matchers: simplified version of listener middleware
 def no_bot_messages(message) -> bool:
-    return message.get("subtype") != "bot_message"
+    return "bot_id" not in message
 
 @app.event(
-    event="message", 
+    event="message",
     matchers=[no_bot_messages]
     # or matchers=[lambda message: message.get("subtype") != "bot_message"]
 )

docs/i18n/ja-jp/docusaurus-plugin-content-docs/current/concepts/listener-middleware.md

@@ -11,11 +11,10 @@ slug: /concepts/listener-middleware
 <span>指定可能な引数の一覧は<a href="https://tools.slack.dev/bolt-python/api-docs/slack_bolt/kwargs_injection/args.html">モジュールドキュメント</a>を参考にしてください。</span>
 
 ```python
-# "bot_message" サブタイプのメッセージを抽出するリスナーミドルウェア
+# ボットからのメッセージをフィルタリングするリスナーミドルウェア
 def no_bot_messages(message, next):
-    subtype = message.get("subtype")
-    if subtype != "bot_message":
-       next()
+    if "bot_id" not in message:
+        next()
 
 # このリスナーは人間によって送信されたメッセージのみを受け取ります
 @app.event(event="message", middleware=[no_bot_messages])
@@ -24,13 +23,13 @@ def log_message(logger, event):
 
 # リスナーマッチャー： 簡略化されたバージョンのリスナーミドルウェア
 def no_bot_messages(message) -> bool:
-    return message.get("subtype") != "bot_message"
+    return "bot_id" not in message
 
 @app.event(
-    event="message", 
+    event="message",
     matchers=[no_bot_messages]
     # or matchers=[lambda message: message.get("subtype") != "bot_message"]
 )
 def log_message(logger, event):
     logger.info(f"(MSG) User: {event['user']}\nMessage: {event['text']}")
-```
+```