refactor: context structure for simple python template

templates/types/simple/fastapi/app/api/routers/chat.py

 from typing import List
 
-from app.utils.index import get_index
 from fastapi import APIRouter, Depends, HTTPException, status
 from llama_index import VectorStoreIndex
 from llama_index.llms.base import MessageRole, ChatMessage
 from pydantic import BaseModel
+from app.context import get_index
 
 chat_router = r = APIRouter()
 

templates/types/simple/fastapi/app/utils/index.py → templates/types/simple/fastapi/app/context.py

-import logging
 import os
+import logging
 
 from llama_index import (
     SimpleDirectoryReader,
@@ -10,16 +10,17 @@ from llama_index import (
 )
 from llama_index.llms import OpenAI
 
-
 STORAGE_DIR = "./storage"  # directory to cache the generated index
 DATA_DIR = "./data"  # directory containing the documents to index
 
-service_context = ServiceContext.from_defaults(
-    llm=OpenAI(model="gpt-3.5-turbo")
-)
-
+def create_base_context():
+    model = os.getenv("MODEL", "gpt-3.5-turbo")
+    return ServiceContext.from_defaults(
+        llm=OpenAI(model=model),
+    )
 
 def get_index():
+    service_context = create_base_context()
     logger = logging.getLogger("uvicorn")
     # check if storage already exists
     if not os.path.exists(STORAGE_DIR):

templates/types/simple/fastapi/pyproject.toml

@@ -9,7 +9,7 @@ readme = "README.md"
 python = "^3.11,<3.12"
 fastapi = "^0.104.1"
 uvicorn = { extras = ["standard"], version = "^0.23.2" }
-llama-index = "^0.8.56"
+llama-index = "^0.9.19"
 pypdf = "^3.17.0"
 python-dotenv = "^1.0.0"