fix: Refactor file reading and async task creation, fix return type in vertex_builds model (#4273)

src/backend/base/langflow/api/v1/chat.py

@@ -329,7 +329,7 @@ async def build_flow(
         client_consumed_queue: asyncio.Queue,
         event_manager: EventManager,
     ) -> None:
-        build_task = asyncio.create_task(asyncio.to_thread(asyncio.run, _build_vertex(vertex_id, graph, event_manager)))
+        build_task = asyncio.create_task(_build_vertex(vertex_id, graph, event_manager))
         try:
             await build_task
         except asyncio.CancelledError as exc:
@@ -361,8 +361,8 @@ async def build_flow(
 
     async def event_generator(event_manager: EventManager, client_consumed_queue: asyncio.Queue) -> None:
         if not data:
-            # using another thread since the DB query is I/O bound
+            # using another task since the build_graph_and_get_order is now an async function
-            vertices_task = asyncio.create_task(asyncio.to_thread(asyncio.run, build_graph_and_get_order()))
+            vertices_task = asyncio.create_task(build_graph_and_get_order())
             try:
                 await vertices_task
             except asyncio.CancelledError:

src/backend/base/langflow/custom/directory_reader/directory_reader.py

@@ -93,9 +93,10 @@ class DirectoryReader:
         _file_path = Path(file_path)
         if not _file_path.is_file():
             return None
-        with _file_path.open(encoding="utf-8") as file:
-            # UnicodeDecodeError: 'charmap' codec can't decode byte 0x9d in position 3069: character maps to <undefined>
         try:
+            with _file_path.open(encoding="utf-8") as file:
+                # UnicodeDecodeError: 'charmap' codec can't decode byte 0x9d in position 3069:
+                # character maps to <undefined>
                 return file.read()
         except UnicodeDecodeError:
             # This is happening in Windows, so we need to open the file in binary mode

src/backend/base/langflow/services/database/models/vertex_builds/model.py

@@ -50,7 +50,7 @@ class VertexBuildBase(SQLModel):
         return truncate_long_strings(data)
 
     @field_serializer("params")
-    def serialize_params(self, data) -> dict:
+    def serialize_params(self, data) -> str:
         return truncate_long_strings(data)