Adds validation for ObjectListWidget.ConfigForm.model field

netbox/extras/dashboard/widgets.py

@@ -9,6 +9,7 @@ import requests
 from django import forms
 from django.conf import settings
 from django.core.cache import cache
+from django.db.models import Model
 from django.template.loader import render_to_string
 from django.urls import NoReverseMatch, resolve, reverse
 from django.utils.translation import gettext as _
@@ -42,6 +43,27 @@ def get_object_type_choices():
     ]
 
 
+def object_list_widget_supports_model(model: Model) -> bool:
+    """Test whether a model is supported by the ObjectListWidget
+
+    In theory there could be more than one reason why a model isn't supported by the
+    ObjectListWidget, although we've only identified one so far--there's no resolve-able 'list' URL
+    for the model. Add more tests if more conditions arise.
+    """
+    def can_resolve_model_list_view(model: Model) -> bool:
+        try:
+            reverse(get_viewname(model, action='list'))
+            return True
+        except Exception:
+            return False
+
+    tests = [
+        can_resolve_model_list_view,
+    ]
+
+    return all(test(model) for test in tests)
+
+
 def get_bookmarks_object_type_choices():
     return [
         (object_type_identifier(ot), object_type_name(ot))
@@ -234,6 +256,17 @@ class ObjectListWidget(DashboardWidget):
                     raise forms.ValidationError(_("Invalid format. URL parameters must be passed as a dictionary."))
             return data
 
+        def clean_model(self):
+            if model_info := self.cleaned_data['model']:
+                app_label, model_name = model_info.split('.')
+                model = ObjectType.objects.get_by_natural_key(app_label, model_name).model_class()
+                if not object_list_widget_supports_model(model):
+                    raise forms.ValidationError(
+                        _(f"Invalid model selection: {self['model'].data} is not supported.")
+                    )
+
+            return model_info
+
     def render(self, request):
         app_label, model_name = self.config['model'].split('.')
         model = ObjectType.objects.get_by_natural_key(app_label, model_name).model_class()

netbox/extras/tests/test_dashboard.py

@@ -4,6 +4,11 @@ from extras.dashboard.widgets import ObjectListWidget
 
 
 class ObjectListWidgetTests(TestCase):
+    def test_widget_config_form_validates_model(self):
+        model_info = 'extras.notification'
+        form = ObjectListWidget.ConfigForm({'model': model_info})
+        self.assertFalse(form.is_valid())
+
     @tag('regression')
     def test_widget_fails_gracefully(self):
         """