Handle System_Settings errors better in middleware (#13982)

* Handle System_Settings.DoesNotExist in get_from_db

Refactor get_from_db method to handle specific exception.

* add error message to UI

Author: valentijnscholten

dojo/context_processors.py

@@ -3,6 +3,7 @@
 
 # import the settings file
 from django.conf import settings
+from django.contrib import messages
 
 from dojo.labels import get_labels
 from dojo.models import Alerts, System_Settings, UserAnnouncement
@@ -39,7 +40,26 @@ def globalize_vars(request):
 
 
 def bind_system_settings(request):
-    return {"system_settings": System_Settings.objects.get()}
+    """Load system settings and display warning if there's a database error."""
+    try:
+        system_settings = System_Settings.objects.get()
+        # Check if there was an error stored on the request (from middleware)
+        if hasattr(request, "system_settings_error"):
+            error_msg = request.system_settings_error
+            messages.add_message(
+                request,
+                messages.WARNING,
+                f"Warning: Unable to load system settings from database: {error_msg}. "
+                "Default values are being used. Please check your database configuration and run migrations if needed.",
+                extra_tags="alert-warning",
+            )
+            # Clear after adding message
+            delattr(request, "system_settings_error")
+    except Exception:
+        # If we can't get settings, return empty dict (will cause errors elsewhere, but that's expected)
+        return {}
+
+    return {"system_settings": system_settings}
 
 
 def bind_alert_count(request):

dojo/middleware.py

@@ -114,6 +114,12 @@ def __init__(self, get_response):
     def __call__(self, request):
         self.load()
         try:
+            # Store error in request for context processor to display
+            # (We can't use messages here because MessageMiddleware runs after this middleware)
+            if hasattr(self._thread_local, "system_settings_error"):
+                request.system_settings_error = self._thread_local.system_settings_error
+                # Clear from thread-local after copying to request
+                delattr(self._thread_local, "system_settings_error")
             return self.get_response(request)
         finally:
             # ensure cleanup happens even if an exception occurs
@@ -132,6 +138,8 @@ def get_system_settings(cls):
     def cleanup(cls, *args, **kwargs):  # noqa: ARG003
         if hasattr(cls._thread_local, "system_settings"):
             del cls._thread_local.system_settings
+        if hasattr(cls._thread_local, "system_settings_error"):
+            delattr(cls._thread_local, "system_settings_error")
 
     @classmethod
     def load(cls):
@@ -147,13 +155,19 @@ class System_Settings_Manager(models.Manager):
 
     def get_from_db(self, *args, **kwargs):
         # logger.debug('refreshing system_settings from db')
+        from dojo.models import System_Settings  # noqa: PLC0415 circular import
         try:
             from_db = super().get(*args, **kwargs)
-        except:
-            from dojo.models import System_Settings  # noqa: PLC0415 circular import
-            # this mimics the existing code that was in filters.py and utils.py.
-            # cases I have seen triggering this is for example manage.py collectstatic inside a docker build where mysql is not available
-            # logger.debug('unable to get system_settings from database, constructing (new) default instance. Exception was:', exc_info=True)
+        except Exception as e:
+            # Store error message in thread-local for middleware to display
+            error_msg = str(e)
+            if hasattr(DojoSytemSettingsMiddleware._thread_local, "system_settings_error"):
+                # Only store the first error to avoid duplicates
+                pass
+            else:
+                DojoSytemSettingsMiddleware._thread_local.system_settings_error = error_msg
+            # Return defaults so app can still start - error will be displayed as warning message
+            # logger.debug('unable to get system_settings from database, returning defaults. Exception was:', exc_info=True)
             return System_Settings()
         return from_db