Middleware was actually useful

modoboa/core/commands/templates/settings.py.tpl

@@ -118,6 +118,7 @@ MIDDLEWARE = (
     'django.contrib.messages.middleware.MessageMiddleware',
     'django.middleware.clickjacking.XFrameOptionsMiddleware',
     'modoboa.core.middleware.LocalConfigMiddleware',
+    'modoboa.lib.middleware.CommonExceptionCatcher',
     'modoboa.lib.middleware.RequestCatcherMiddleware',
 )
 

modoboa/lib/middleware.py

@@ -1,8 +1,30 @@
 """Custom middlewares."""
 
+from django.http import JsonResponse
 from django.utils.deprecation import MiddlewareMixin
+from django.utils.encoding import smart_str
 
 from modoboa.lib import signals as lib_signals
+from modoboa.lib.exceptions import ModoboaException
+from modoboa.lib.web_utils import _render_error
+
+
+def is_ajax(request):
+    return request.META.get("HTTP_X_REQUESTED_WITH") == "XMLHttpRequest"
+
+
+class CommonExceptionCatcher(MiddlewareMixin):
+    """Modoboa exceptions catcher."""
+
+    def process_exception(self, request, exception):
+        if not isinstance(exception, ModoboaException):
+            return None
+
+        if "/api/" in request.path:
+            http_code = exception.http_code if exception.http_code else 500
+            return JsonResponse({"error": str(exception)}, status=http_code)
+
+        return _render_error(request, user_context={"error": smart_str(exception)})
 
 
 class RequestCatcherMiddleware(MiddlewareMixin):

modoboa/lib/web_utils.py

@@ -2,6 +2,14 @@
 
 import re
 
+from django.shortcuts import render
+
+
+def _render_error(request, errortpl="error", user_context=None):
+    if user_context is None:
+        user_context = {}
+    return render(request, f"common/{errortpl}.html", user_context)
+
 
 def size2integer(value: str, output_unit: str = "B") -> int:
     """

test_project/test_project/settings.py

@@ -129,6 +129,7 @@ MIDDLEWARE = (
     "django.contrib.messages.middleware.MessageMiddleware",
     "django.middleware.clickjacking.XFrameOptionsMiddleware",
     "modoboa.core.middleware.LocalConfigMiddleware",
+    "modoboa.lib.middleware.CommonExceptionCatcher",
     "modoboa.lib.middleware.RequestCatcherMiddleware",
 )