Fixes #20977: Apply defaults for missing script variables (#21295)

Ensure script variables fall back to their defined defaults when a value is not
submitted (e.g. via "Run again" or other minimal POSTs).

- Populate omitted script variables with their initial/default values before
  validation and job enqueueing
- Treat falsy defaults (e.g. False/0) as valid defaults
- Add a test asserting defaults are included in enqueued job data
- Remove the redundant default from ScriptValidationErrorTest

netbox/extras/scripts.py

@@ -61,7 +61,7 @@ class ScriptVariable:
             self.field_attrs['label'] = label
         if description:
             self.field_attrs['help_text'] = description
-        if default:
+        if default is not None:
             self.field_attrs['initial'] = default
         if widget:
             self.field_attrs['widget'] = widget

netbox/extras/tests/test_views.py

@@ -1,6 +1,7 @@
 from django.contrib.contenttypes.models import ContentType
 from django.urls import reverse
 from django.test import tag
+from unittest.mock import patch, PropertyMock
 
 from core.choices import ManagedFileRootPathChoices
 from core.events import *
@@ -906,7 +907,7 @@ class ScriptValidationErrorTest(TestCase):
     user_permissions = ['extras.view_script', 'extras.run_script']
 
     class TestScriptMixin:
-        bar = IntegerVar(min_value=0, max_value=30, default=30)
+        bar = IntegerVar(min_value=0, max_value=30)
 
     class TestScriptClass(TestScriptMixin, PythonClass):
         class Meta:
@@ -930,8 +931,6 @@ class ScriptValidationErrorTest(TestCase):
 
     @tag('regression')
     def test_script_validation_error_displays_message(self):
-        from unittest.mock import patch
-
         url = reverse('extras:script', kwargs={'pk': self.script.pk})
 
         with patch('extras.views.get_workers_for_queue', return_value=['worker']):
@@ -944,8 +943,6 @@ class ScriptValidationErrorTest(TestCase):
 
     @tag('regression')
     def test_script_validation_error_no_toast_for_fieldset_fields(self):
-        from unittest.mock import patch, PropertyMock
-
         class FieldsetScript(PythonClass):
             class Meta:
                 name = 'Fieldset test'
@@ -967,3 +964,42 @@ class ScriptValidationErrorTest(TestCase):
         self.assertEqual(response.status_code, 200)
         messages = list(response.context['messages'])
         self.assertEqual(len(messages), 0)
+
+
+class ScriptDefaultValuesTest(TestCase):
+    user_permissions = ['extras.view_script', 'extras.run_script']
+
+    class TestScriptClass(PythonClass):
+        class Meta:
+            name = 'Test script'
+            commit_default = False
+
+        bool_default_true = BooleanVar(default=True)
+        bool_default_false = BooleanVar(default=False)
+        int_with_default = IntegerVar(default=0)
+        int_without_default = IntegerVar(required=False)
+
+        def run(self, data, commit):
+            return "Complete"
+
+    @classmethod
+    def setUpTestData(cls):
+        module = ScriptModule.objects.create(file_root=ManagedFileRootPathChoices.SCRIPTS, file_path='test_script.py')
+        cls.script = Script.objects.create(module=module, name='Test script', is_executable=True)
+
+    def setUp(self):
+        super().setUp()
+        Script.python_class = property(lambda self: ScriptDefaultValuesTest.TestScriptClass)
+
+    def test_default_values_are_used(self):
+        url = reverse('extras:script', kwargs={'pk': self.script.pk})
+
+        with patch('extras.views.get_workers_for_queue', return_value=['worker']):
+            with patch('extras.jobs.ScriptJob.enqueue') as mock_enqueue:
+                mock_enqueue.return_value.pk = 1
+                self.client.post(url, {})
+                call_kwargs = mock_enqueue.call_args.kwargs
+                self.assertEqual(call_kwargs['data']['bool_default_true'], True)
+                self.assertEqual(call_kwargs['data']['bool_default_false'], False)
+                self.assertEqual(call_kwargs['data']['int_with_default'], 0)
+                self.assertIsNone(call_kwargs['data']['int_without_default'])

netbox/extras/views.py

@@ -1511,7 +1511,13 @@ class ScriptView(BaseScriptView):
                 'script': script,
             })
 
-        form = script_class.as_form(request.POST, request.FILES)
+        # Populate missing variables with their default values, if defined
+        post_data = request.POST.copy()
+        for name, var in script_class._get_vars().items():
+            if name not in post_data and (initial := var.field_attrs.get('initial')) is not None:
+                post_data[name] = initial
+
+        form = script_class.as_form(post_data, request.FILES)
 
         # Allow execution only if RQ worker process is running
         if not get_workers_for_queue('default'):