Fix TypeError when update_fields=None in model save methods (#16466)

Django allows passing update_fields=None to model.save() to mean 'update all fields'.
However, kwargs.get('update_fields', []) returns None when the key exists with a None value,
rather than the default empty list.

This caused crashes in mark_field_for_save() and other code that assumes update_fields is
a list when doing membership tests ('field' not in update_fields) or append operations.

Changed pattern from:
  update_fields = kwargs.get('update_fields', [])

To:
  update_fields = kwargs.get('update_fields') or []

This correctly handles:
- Key missing: get() returns None → or [] gives []
- Key present with None: get() returns None → or [] gives []
- Key present with list: get() returns list → or [] keeps the list

Fixed in 12 locations across 8 model files:
- awx/main/models/base.py (3 instances)
- awx/main/models/unified_jobs.py (2)
- awx/main/models/jobs.py (2)
- awx/main/models/ad_hoc_commands.py
- awx/main/models/inventory.py
- awx/main/models/notifications.py
- awx/main/models/projects.py
- awx/main/models/workflow.py

Fixes task manager crashes with:
TypeError: argument of type 'NoneType' is not iterable

awx/main/models/ad_hoc_commands.py

@@ -211,7 +211,7 @@ class AdHocCommand(UnifiedJob, JobNotificationMixin):
         return AdHocCommand.objects.create(**data)
 
     def save(self, *args, **kwargs):
-        update_fields = kwargs.get('update_fields', [])
+        update_fields = kwargs.get('update_fields') or []
 
         def add_to_update_fields(name):
             if name not in update_fields:

awx/main/models/base.py

@@ -177,7 +177,7 @@ class CreatedModifiedModel(BaseModel):
     )
 
     def save(self, *args, **kwargs):
-        update_fields = list(kwargs.get('update_fields', []))
+        update_fields = list(kwargs.get('update_fields') or [])
         # Manually perform auto_now_add and auto_now logic.
         if not self.pk and not self.created:
             self.created = now()
@@ -207,7 +207,7 @@ class PasswordFieldsModel(BaseModel):
         new_instance = not bool(self.pk)
         # If update_fields has been specified, add our field names to it,
         # if it hasn't been specified, then we're just doing a normal save.
-        update_fields = kwargs.get('update_fields', [])
+        update_fields = kwargs.get('update_fields') or []
         # When first saving to the database, don't store any password field
         # values, but instead save them until after the instance is created.
         # Otherwise, store encrypted values to the database.
@@ -322,7 +322,7 @@ class PrimordialModel(HasEditsMixin, CreatedModifiedModel):
             self._prior_values_store = {}
 
     def save(self, *args, **kwargs):
-        update_fields = kwargs.get('update_fields', [])
+        update_fields = kwargs.get('update_fields') or []
         user = get_current_user()
         if user and not user.id:
             user = None

awx/main/models/inventory.py

@@ -1149,7 +1149,7 @@ class InventorySource(UnifiedJobTemplate, InventorySourceOptions, CustomVirtualE
 
         # If update_fields has been specified, add our field names to it,
         # if it hasn't been specified, then we're just doing a normal save.
-        update_fields = kwargs.get('update_fields', [])
+        update_fields = kwargs.get('update_fields') or []
         is_new_instance = not bool(self.pk)
 
         # Set name automatically. Include PK (or placeholder) to make sure the names are always unique.

awx/main/models/jobs.py

@@ -347,7 +347,7 @@ class JobTemplate(
             return actual_slice_count
 
     def save(self, *args, **kwargs):
-        update_fields = kwargs.get('update_fields', [])
+        update_fields = kwargs.get('update_fields') or []
         # if project is deleted for some reason, then keep the old organization
         # to retain ownership for organization admins
         if self.project and self.project.organization_id != self.organization_id:
@@ -1165,7 +1165,7 @@ class JobHostSummary(CreatedModifiedModel):
         # if it hasn't been specified, then we're just doing a normal save.
         if self.host is not None:
             self.host_name = self.host.name
-        update_fields = kwargs.get('update_fields', [])
+        update_fields = kwargs.get('update_fields') or []
         self.failed = bool(self.dark or self.failures)
         update_fields.append('failed')
         super(JobHostSummary, self).save(*args, **kwargs)

awx/main/models/notifications.py

@@ -99,7 +99,7 @@ class NotificationTemplate(CommonModelNameNotUnique):
 
     def save(self, *args, **kwargs):
         new_instance = not bool(self.pk)
-        update_fields = kwargs.get('update_fields', [])
+        update_fields = kwargs.get('update_fields') or []
 
         # preserve existing notification messages if not overwritten by new messages
         if not new_instance:

awx/main/models/projects.py

@@ -367,7 +367,7 @@ class Project(UnifiedJobTemplate, ProjectOptions, ResourceMixin, CustomVirtualEn
         pre_save_vals = getattr(self, '_prior_values_store', {})
         # If update_fields has been specified, add our field names to it,
         # if it hasn't been specified, then we're just doing a normal save.
-        update_fields = kwargs.get('update_fields', [])
+        update_fields = kwargs.get('update_fields') or []
         self._skip_update = bool(kwargs.pop('skip_update', False))
         # Create auto-generated local path if project uses SCM.
         if self.pk and self.scm_type and not self.local_path.startswith('_'):

awx/main/models/unified_jobs.py

@@ -305,7 +305,7 @@ class UnifiedJobTemplate(PolymorphicModel, CommonModelNameNotUnique, ExecutionEn
     def save(self, *args, **kwargs):
         # If update_fields has been specified, add our field names to it,
         # if it hasn't been specified, then we're just doing a normal save.
-        update_fields = kwargs.get('update_fields', [])
+        update_fields = kwargs.get('update_fields') or []
         # Update status and last_updated fields.
         if not getattr(_inventory_updates, 'is_updating', False):
             updated_fields = self._set_status_and_last_job_run(save=False)
@@ -877,7 +877,7 @@ class UnifiedJob(
         """
         # If update_fields has been specified, add our field names to it,
         # if it hasn't been specified, then we're just doing a normal save.
-        update_fields = kwargs.get('update_fields', [])
+        update_fields = kwargs.get('update_fields') or []
 
         # Get status before save...
         status_before = self.status or 'new'

awx/main/models/workflow.py

@@ -900,7 +900,7 @@ class WorkflowApproval(UnifiedJob, JobNotificationMixin):
         return 'workflow_approval_template'
 
     def save(self, *args, **kwargs):
-        update_fields = list(kwargs.get('update_fields', []))
+        update_fields = list(kwargs.get('update_fields') or [])
         if self.timeout != 0 and ((not self.pk) or (not update_fields) or ('timeout' in update_fields)):
             if not self.created:  # on creation, created will be set by parent class, so we fudge it here
                 created = now()