15353 add better script error message (#15441)

* 15353 add better script error message

* Simplify _get_script_class() & add docstring

---------

Co-authored-by: Jeremy Stretch <jstretch@netboxlabs.com>

netbox/extras/models/scripts.py

@@ -96,6 +96,7 @@ class ScriptModule(PythonModuleMixin, JobsMixin, ManagedFile):
     Proxy model for script module files.
     """
     objects = ScriptModuleManager()
+    error = None
 
     event_rules = GenericRelation(
         to='extras.EventRule',
@@ -126,6 +127,7 @@ class ScriptModule(PythonModuleMixin, JobsMixin, ManagedFile):
         try:
             module = self.get_module()
         except Exception as e:
+            self.error = e
             logger.debug(f"Failed to load script: {self.python_name} error: {e}")
             module = None
 

netbox/extras/views.py

@@ -1052,12 +1052,27 @@ class ScriptListView(ContentTypePermissionRequiredMixin, View):
         })
 
 
-class ScriptView(generic.ObjectView):
+class BaseScriptView(generic.ObjectView):
     queryset = Script.objects.all()
 
+    def _get_script_class(self, script):
+        """
+        Return an instance of the Script's Python class
+        """
+        if script_class := script.python_class:
+            return script_class()
+
+
+class ScriptView(BaseScriptView):
+
     def get(self, request, **kwargs):
         script = self.get_object(**kwargs)
-        script_class = script.python_class()
+        script_class = self._get_script_class(script)
+        if not script_class:
+            return render(request, 'extras/script.html', {
+                'script': script,
+            })
+
         form = script_class.as_form(initial=normalize_querydict(request.GET))
 
         return render(request, 'extras/script.html', {
@@ -1069,11 +1084,16 @@ class ScriptView(generic.ObjectView):
 
     def post(self, request, **kwargs):
         script = self.get_object(**kwargs)
-        script_class = script.python_class()
 
         if not request.user.has_perm('extras.run_script', obj=script):
             return HttpResponseForbidden()
 
+        script_class = self._get_script_class(script)
+        if not script_class:
+            return render(request, 'extras/script.html', {
+                'script': script,
+            })
+
         form = script_class.as_form(request.POST, request.FILES)
 
         # Allow execution only if RQ worker process is running
@@ -1103,21 +1123,22 @@ class ScriptView(generic.ObjectView):
         })
 
 
-class ScriptSourceView(generic.ObjectView):
+class ScriptSourceView(BaseScriptView):
     queryset = Script.objects.all()
 
     def get(self, request, **kwargs):
         script = self.get_object(**kwargs)
+        script_class = self._get_script_class(script)
 
         return render(request, 'extras/script/source.html', {
             'script': script,
-            'script_class': script.python_class(),
+            'script_class': script_class,
             'job_count': script.jobs.count(),
             'tab': 'source',
         })
 
 
-class ScriptJobsView(generic.ObjectView):
+class ScriptJobsView(BaseScriptView):
     queryset = Script.objects.all()
 
     def get(self, request, **kwargs):