From 0fb33825d91361c59b8d84427d5f35f838674a19 Mon Sep 17 00:00:00 2001
From: Gabriel Luiz Freitas Almeida <gabriel@logspace.ai>
Date: Wed, 21 Jun 2023 14:04:45 -0300
Subject: [PATCH] =?UTF-8?q?=F0=9F=90=9B=20fix(chat.py):=20change=20data=20?=
 =?UTF-8?q?to=20error=20in=20yield=20statement=20when=20flow=5Fid=20is=20i?=
 =?UTF-8?q?nvalid=20=F0=9F=90=9B=20fix(chat.py):=20catch=20exception=20whe?=
 =?UTF-8?q?n=20building=20graph=20and=20yield=20error=20message=20When=20t?=
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 =?UTF-8?q?ld=20return=20an=20error=20message=20instead=20of=20data.=20Add?=
 =?UTF-8?q?itionally,=20when=20building=20the=20graph,=20an=20exception=20?=
 =?UTF-8?q?could=20occur,=20so=20we=20added=20a=20try-except=20block=20to?=
 =?UTF-8?q?=20catch=20any=20exceptions=20and=20yield=20an=20error=20messag?=
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---
 src/backend/langflow/api/v1/chat.py | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/backend/langflow/api/v1/chat.py b/src/backend/langflow/api/v1/chat.py
index ed0caeba2..8d754975b 100644
--- a/src/backend/langflow/api/v1/chat.py
+++ b/src/backend/langflow/api/v1/chat.py
@@ -75,7 +75,7 @@ async def stream_build(flow_id: str):
         try:
             if flow_id not in flow_data_store:
                 error_message = "Invalid session ID"
-                yield f"data: {json.dumps({'error': error_message})}\n\n"
+                yield f"error: {json.dumps({'error': error_message})}\n\n"
                 return
 
             graph_data = flow_data_store[flow_id].get("data")
@@ -86,7 +86,15 @@ async def stream_build(flow_id: str):
                 return
 
             logger.debug("Building langchain object")
-            graph = Graph.from_payload(graph_data)
+            try:
+                # Some error could happen when building the graph
+                graph = Graph.from_payload(graph_data)
+            except Exception as exc:
+                logger.error(exc)
+                error_message = str(exc)
+                yield f"error: {json.dumps({'error': error_message})}\n\n"
+                return
+
             number_of_nodes = len(graph.nodes)
             for i, vertex in enumerate(graph.generator_build(), 1):
                 try: