Protect views from viewing if the user has no right to view an object

apps/permission/templatetags/perms.py

@@ -0,0 +1,42 @@
+# Copyright (C) 2018-2020 by BDE ENS Paris-Saclay
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+from django.contrib.contenttypes.models import ContentType
+from django.template.defaultfilters import stringfilter
+
+from logs.middlewares import get_current_authenticated_user
+from django import template
+
+from member.backends import PermissionBackend
+
+
+def has_perm(value):
+    return get_current_authenticated_user().has_perm(value)
+
+
+@stringfilter
+def not_empty_model_list(model_name):
+    user = get_current_authenticated_user()
+    if user.is_superuser:
+        return True
+    spl = model_name.split(".")
+    ct = ContentType.objects.get(app_label=spl[0], model=spl[1])
+    qs = ct.model_class().objects.filter(PermissionBackend.filter_queryset(user, ct, "view"))
+    return qs.exists()
+
+
+@stringfilter
+def not_empty_model_change_list(model_name):
+    user = get_current_authenticated_user()
+    if user.is_superuser:
+        return True
+    spl = model_name.split(".")
+    ct = ContentType.objects.get(app_label=spl[0], model=spl[1])
+    qs = ct.model_class().objects.filter(PermissionBackend.filter_queryset(user, ct, "change"))
+    return qs.exists()
+
+
+register = template.Library()
+register.filter('has_perm', has_perm)
+register.filter('not_empty_model_list', not_empty_model_list)
+register.filter('not_empty_model_change_list', not_empty_model_change_list)