Refactor common view functionality into mixin

src/servala/frontend/views/service.py

@@ -159,15 +159,15 @@ class ServiceOfferingDetailView(OrganizationViewMixin, HtmxViewMixin, DetailView
         return self.render_to_response(context)
 
 
-class ServiceInstanceDetailView(OrganizationViewMixin, DetailView):
-    """View to display details of a specific service instance."""
-
-    template_name = "frontend/organizations/service_instance_detail.html"
-    context_object_name = "instance"
+class ServiceInstanceMixin:
     model = ServiceInstance
-    permission_type = "view"
+    context_object_name = "instance"
     slug_field = "name"
 
+    def dispatch(self, *args, **kwargs):
+        self._has_warned = False
+        return super().dispatch(*args, **kwargs)
+
     def get_queryset(self):
         """Return service instance for the current organization."""
         return ServiceInstance.objects.filter(
@@ -178,6 +178,35 @@ class ServiceInstanceDetailView(OrganizationViewMixin, DetailView):
             "context__service_definition__service",
         )
 
+    def get_object(self, **kwargs):
+        instance = super().get_object(**kwargs)
+        if (
+            not instance.kubernetes_object
+            and not instance.is_deleted
+            and not self._has_warned
+        ):
+            messages.warning(
+                self.request,
+                _(
+                    "Could not retrieve instance details from Kubernetes. It might have been deleted externally."
+                ),
+            )
+            self._has_warned = True
+        return instance
+
+
+class ServiceInstanceDetailView(
+    ServiceInstanceMixin, OrganizationViewMixin, DetailView
+):
+    template_name = "frontend/organizations/service_instance_detail.html"
+    permission_type = "view"
+
+    def get_context_data(self, **kwargs):
+        context = super().get_context_data(**kwargs)
+        if self.object.kubernetes_object and self.object.spec:
+            context["spec_fieldsets"] = self.get_nested_spec()
+        return context
+
     def get_nested_spec(self):
         """
         Organize spec data into fieldsets similar to how the form does it.