Fix Docker Build Errors and Refactor the code in src/flask.py

.gitignore

@@ -5,3 +5,4 @@ build/
 *.db
 *.egg-info/
 *.pyc
+foo.db

Dockerfile

@@ -1,6 +1,6 @@
 FROM cs50/cli
 
-RUN sudo apt update && sudo apt install --yes libmysqlclient-dev pgloader pkg-config postgresql
+RUN sudo apt update && sudo apt install --yes libmysqlclient-dev pgloader pkg-config postgresql && sudo rm -rf /var/lib/apt/lists/*
 RUN sudo pip3 install mysqlclient psycopg2-binary
 
 WORKDIR /mnt

docker-compose.yml

@@ -4,7 +4,7 @@ services:
     container_name: python-cs50
     depends_on:
       - mysql
-      - postgres 
+      - postgres
     environment:
       MYSQL_HOST: mysql
       POSTGRESQL_HOST: postgres
@@ -30,4 +30,4 @@ services:
       POSTGRES_PASSWORD: postgres
       POSTGRES_DB: test
     ports:
-    - 5432:5432
+      - 5432:5432

src/cs50/flask.py

@@ -1,47 +1,92 @@
+import importlib.util
 import os
-import pkgutil
 import sys
+import warnings
 
 
 def _wrap_flask(f):
+    """
+    Wraps the Flask class's __init__ method if necessary,
+    primarily to add ProxyFix for CS50 IDE online environments.
+    """
     if f is None:
         return
 
-    from packaging.version import Version, InvalidVersion
-    from .cs50 import _formatException
+    # Dynamically import packaging only when needed
+    try:
+        from packaging.version import Version, InvalidVersion
+    except ImportError:
+        # If packaging is not installed, cannot check version, so assume we can't wrap
+        return
+
 
     try:
+        # Check Flask version compatibility
         if Version(f.__version__) < Version("1.0"):
             return
-    except InvalidVersion:
+    except (InvalidVersion, AttributeError):
+        # Handle invalid version strings or if Flask doesn't have __version__
+        return
+    except Exception:
         return
 
+    # Apply ProxyFix only in CS50 IDE online environment
     if os.getenv("CS50_IDE_TYPE") == "online":
-        from werkzeug.middleware.proxy_fix import ProxyFix
+        try:
+            from werkzeug.middleware.proxy_fix import ProxyFix
+        except ImportError:
+            # If werkzeug (a Flask dependency) is missing or ProxyFix moved, cannot apply fix
+            return
 
         _flask_init_before = f.Flask.__init__
 
         def _flask_init_after(self, *args, **kwargs):
             _flask_init_before(self, *args, **kwargs)
-            self.wsgi_app = ProxyFix(
-                self.wsgi_app, x_proto=1
-            )  # For HTTPS-to-HTTP proxy
+            # Apply ProxyFix to handle reverse proxies in CS50 IDE (x_proto=1 trusts X-Forwarded-Proto header)
+            self.wsgi_app = ProxyFix(self.wsgi_app, x_proto=1)
 
+        # Monkey-patch Flask's __init__
         f.Flask.__init__ = _flask_init_after
 
 
-# If Flask was imported before cs50
+# --- Main Logic ---
+
+# Check if Flask was already imported before cs50 library was imported
 if "flask" in sys.modules:
     _wrap_flask(sys.modules["flask"])
 
-# If Flask wasn't imported
+# If Flask hasn't been imported yet, set up patching for when it *is* imported
 else:
-    flask_loader = pkgutil.get_loader("flask")
-    if flask_loader:
-        _exec_module_before = flask_loader.exec_module
+    # Find the module specification for Flask using the recommended importlib utility
+    # This replaces the deprecated pkgutil.get_loader
+    flask_spec = importlib.util.find_spec("flask")
+
+    # Check if the spec was found and if it has a loader
+    # (Some namespace packages might not have a loader, but Flask should)
+    if flask_spec and flask_spec.loader:
+
+        # Ensure the loader has the exec_module method (standard loaders do)
+        if hasattr(flask_spec.loader, 'exec_module'):
+
+            # Get the original exec_module method from the loader
+            _exec_module_before = flask_spec.loader.exec_module
+
+            # Define a wrapper function for exec_module
+            # This function will be called by the import system when Flask is loaded
+            def _exec_module_after(module):
+                # Execute the original module loading logic first
+                _exec_module_before(module)
+                # Now that the module ('flask') is fully loaded and present in sys.modules,
+                # apply our custom wrapping logic.
+                _wrap_flask(module) # Pass the loaded module object to _wrap_flask
+
+            # Monkey-patch the loader's exec_module method with our wrapper
+            flask_spec.loader.exec_module = _exec_module_after
 
-        def _exec_module_after(*args, **kwargs):
-            _exec_module_before(*args, **kwargs)
-            _wrap_flask(sys.modules["flask"])
+        else:
+            # Handle the unlikely case where the loader doesn't have exec_module
+            warnings.warn("Flask loader doesn't support the expected exec_module interface")
 
-        flask_loader.exec_module = _exec_module_after
+    else:
+        # Handle the case where Flask spec wasn't found (Flask not installed?)
+        warnings.warn("Flask module specification not found. Flask may not be installed.")