feat: add nested webhook message support

freqtrade/rpc/webhook.py

@@ -81,6 +81,20 @@ class Webhook(RPCHandler):
             return None
         return valuedict
 
+    def recursive_format(self, obj: dict | list | str, msg: RPCSendMsg):
+        """
+        Format the given object using the provided message.
+        """
+        match obj:
+            case dict():
+                return {k: self.recursive_format(v, msg) for k, v in obj.items()}
+            case list():
+                return [self.recursive_format(item, msg) for item in obj]
+            case str():
+                return obj.format(**msg)
+            case _:
+                return obj
+
     def send_msg(self, msg: RPCSendMsg) -> None:
         """Send a message to telegram channel"""
         try:
@@ -90,7 +104,7 @@ class Webhook(RPCHandler):
                 logger.debug("Message type '%s' not configured for webhooks", msg["type"])
                 return
 
-            payload = {key: value.format(**msg) for (key, value) in valuedict.items()}
+            payload = self.recursive_format(valuedict, msg)
             self._send_msg(payload)
         except KeyError as exc:
             logger.exception(