From baeadf018d4332744f864b155c503272baa1a13b Mon Sep 17 00:00:00 2001
From: Gabriel Luiz Freitas Almeida <gabriel@logspace.ai>
Date: Mon, 12 Jun 2023 13:03:46 -0300
Subject: [PATCH] =?UTF-8?q?=E2=9C=A8=20feat(chat.py):=20improve=20SSE=20re?=
 =?UTF-8?q?sponse=20by=20adding=20node=20id=20and=20valid=20flag=20The=20c?=
 =?UTF-8?q?hanges=20in=20this=20commit=20handle=20exceptions=20that=20may?=
 =?UTF-8?q?=20occur=20when=20creating=20a=20streaming=20response.=20The=20?=
 =?UTF-8?q?try-except=20block=20ensures=20that=20any=20exceptions=20are=20?=
 =?UTF-8?q?caught=20and=20an=20appropriate=20response=20is=20returned.=20A?=
 =?UTF-8?q?dditionally,=20the=20SSE=20response=20has=20been=20improved=20b?=
 =?UTF-8?q?y=20adding=20a=20valid=20flag=20and=20node=20id=20to=20the=20re?=
 =?UTF-8?q?sponse.=20This=20provides=20more=20information=20to=20the=20cli?=
 =?UTF-8?q?ent=20about=20the=20status=20of=20the=20node=20build=20and=20al?=
 =?UTF-8?q?lows=20for=20better=20error=20handling.=20=F0=9F=90=9B=20fix(ch?=
 =?UTF-8?q?at.py):=20handle=20exceptions=20when=20creating=20a=20streaming?=
 =?UTF-8?q?=20response?=
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---
 src/backend/langflow/api/v1/chat.py | 49 ++++++++++++++++-------------
 1 file changed, 27 insertions(+), 22 deletions(-)

diff --git a/src/backend/langflow/api/v1/chat.py b/src/backend/langflow/api/v1/chat.py
index 1353090d6..4d9d85a58 100644
--- a/src/backend/langflow/api/v1/chat.py
+++ b/src/backend/langflow/api/v1/chat.py
@@ -1,7 +1,6 @@
 import json
 from fastapi import (
     APIRouter,
-    HTTPException,
     WebSocket,
     WebSocketDisconnect,
     WebSocketException,
@@ -63,29 +62,35 @@ async def stream_build(flow_id: str):
             yield f"data: {json.dumps({'error': error_message})}\n\n"
             return
 
-        try:
-            logger.debug("Building langchain object")
-            graph = Graph.from_payload(graph_data)
-            for node_repr, node_id in graph.generator_build():
+        logger.debug("Building langchain object")
+        graph = Graph.from_payload(graph_data)
+        for node in graph.generator_build():
+            try:
+                node.build()
+                params = node._built_object_repr()
+                valid = True
                 logger.debug(
-                    f"Building node {node_repr[:50]}{'...' if len(node_repr) > 50 else ''}"
+                    f"Building node {params[:50]}{'...' if len(params) > 50 else ''}"
                 )
-                response = json.dumps(
-                    {
-                        "valid": True,
-                        "params": node_repr,
-                        "id": node_id,
-                    }
-                )
-                yield f"data: {response}\n\n"  # SSE format
+            except Exception as exc:
+                params = str(exc)
+                valid = False
 
-            chat_manager.set_cache(flow_id, graph.build())
-            final_response = json.dumps({"end_of_stream": True})
-            yield f"data: {final_response}\n\n"  # SSE format
+            response = json.dumps(
+                {
+                    "valid": valid,
+                    "params": params,
+                    "id": node.id,
+                }
+            )
+            yield f"data: {response}\n\n"  # SSE format
 
-        except Exception as exc:
-            logger.exception(exc)
-            error_response = json.dumps({"valid": False, "params": str(exc)})
-            yield f"data: {error_response}\n\n"  # SSE format
+        chat_manager.set_cache(flow_id, graph.build())
+        final_response = json.dumps({"end_of_stream": True})
+        yield f"data: {final_response}\n\n"  # SSE format
 
-    return StreamingResponse(event_stream(flow_id), media_type="text/event-stream")
+    try:
+        return StreamingResponse(event_stream(flow_id), media_type="text/event-stream")
+    except Exception as exc:
+        logger.error(exc)
+        return JSONResponse(content={"error": str(exc)})