Do not cache SPA HTML pages in client (#635)

backend/api/static_files.py

@@ -1,18 +1,9 @@
-"""Single-page application middleware.
-
-Our application is organized as a single-page application (SPA). This middleware class
-extends the functionality of the StaticFiles middleware and was inspired by: 
-<https://stackoverflow.com/questions/63069190/how-to-capture-arbitrary-paths-at-one-route-in-fastapi>
-"""
-
-__authors__ = ["Kris Jordan"]
-__copyright__ = "Copyright 2023"
-__license__ = "MIT"
-
+from fastapi import Response
+from starlette.responses import FileResponse
+from starlette.staticfiles import StaticFiles
+from starlette.types import Scope
 import os
 
-from fastapi.staticfiles import StaticFiles
-
 
 class StaticFileMiddleware(StaticFiles):
     def __init__(self, directory: os.PathLike, index: str = "index.html") -> None:
@@ -35,3 +26,21 @@ def lookup_path(self, path: str) -> tuple[str, os.stat_result | None]:
             return (full_path, stat_result)
         else:
             return (full_path, stat_result)
+
+    async def get_response(self, path: str, scope: Scope) -> Response:
+        """Override get_response to set cache-control headers for index.html."""
+
+        # Explicitly handle the root path ("/")
+        if path in ["", "/", "."]:
+            path = self.index  # Treat the root as a request for index.html
+
+        full_path, _ = self.lookup_path(path)
+
+        # If serving index.html, set cache-control header to prevent caching
+        if full_path.endswith(self.index):
+            response = FileResponse(full_path)
+            response.headers["Cache-Control"] = "no-store"
+            return response
+
+        # For other static files, let the default caching behavior handle it
+        return await super().get_response(path, scope)

backend/main.py

@@ -110,12 +110,12 @@
 
 # Add application-wide exception handling middleware for commonly encountered API Exceptions
 @app.exception_handler(UserPermissionException)
-def permission_exception_handler(request: Request, e: UserPermissionException):
+def user_permission_exception_handler(request: Request, e: UserPermissionException):
     return JSONResponse(status_code=403, content={"message": str(e)})
 
 
 @app.exception_handler(CoursePermissionException)
-def permission_exception_handler(request: Request, e: UserPermissionException):
+def course_permission_exception_handler(request: Request, e: UserPermissionException):
     return JSONResponse(status_code=403, content={"message": str(e)})
 
 
@@ -132,9 +132,7 @@ def reservation_exception_handler(request: Request, e: ReservationException):
 
 
 @app.exception_handler(CourseDataScrapingException)
-def resource_not_found_exception_handler(
-    request: Request, e: CourseDataScrapingException
-):
+def course_data_scraping_exception(request: Request, e: CourseDataScrapingException):
     return JSONResponse(status_code=500, content={"message": str(e)})