Refactor main.py to include middleware for

flattening query string lists.

src/backend/langflow/main.py

@@ -1,19 +1,16 @@
 from pathlib import Path
 from typing import Optional
-from fastapi import FastAPI
+from urllib.parse import urlencode
+
+from fastapi import FastAPI, Request
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import FileResponse
 from fastapi.staticfiles import StaticFiles
 
 from langflow.api import router
-
-
 from langflow.interface.utils import setup_llm_caching
-from langflow.services.utils import initialize_services
 from langflow.services.plugins.langfuse import LangfuseInstance
-from langflow.services.utils import (
-    teardown_services,
-)
+from langflow.services.utils import initialize_services, teardown_services
 from langflow.utils.logger import configure
 
 
@@ -23,7 +20,6 @@ def create_app():
     configure()
 
     app = FastAPI()
-
     origins = ["*"]
 
     app.add_middleware(
@@ -34,6 +30,16 @@ def create_app():
         allow_headers=["*"],
     )
 
+    @app.middleware("http")
+    async def flatten_query_string_lists(request: Request, call_next):
+        flattened = []
+        for key, value in request.query_params.multi_items():
+            flattened.extend((key, entry) for entry in value.split(","))
+
+        request.scope["query_string"] = urlencode(flattened, doseq=True).encode("utf-8")
+
+        return await call_next(request)
+
     @app.get("/health")
     def health():
         return {"status": "ok"}
@@ -96,6 +102,7 @@ def setup_app(
 
 if __name__ == "__main__":
     import uvicorn
+
     from langflow.__main__ import get_number_of_workers
 
     configure()