assign-vlans view throws error on virtual machines where the cluster has no site

[kasimon]

Issue type

[ ] Feature request
[X] Bug report
[ ] Documentation
[ ] Housekeeping

Environment

• Python version: 2.7.13
• NetBox version: 2.3.5

Description

When trying to assign a vlan to an interface of a virtual machine where the cluster has no site set, a server error happens:

 Server Error
There was a problem with your request. Please contact an administrator.
The complete exception is provided below:

'NoneType' object has no attribute 'name'
If further assistance is required, please post to the NetBox mailing list.

The url is netbox/dcim/interfaces/447/assign-vlans/?return_url=/netbox/virtualization/vm-interfaces/447/edit/

The problem seems to be this line: https://github.com/digitalocean/netbox/blob/97863115ba2f8e889b8741099c5b1a6eb0a2051b/netbox/dcim/forms.py#L1784

Here is the stack trace:

Environment:


Request Method: GET
Request URL: http://REDACTED/netbox/dcim/interfaces/447/assign-vlans/?return_url=/netbox/virtualization/vm-interfaces/447/edit/

Django Version: 1.11.14
Python Version: 2.7.13
Installed Applications:
('django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.humanize',
 'corsheaders',
 'debug_toolbar',
 'django_filters',
 'django_tables2',
 'mptt',
 'rest_framework',
 'timezone_field',
 'circuits',
 'dcim',
 'ipam',
 'extras',
 'secrets',
 'tenancy',
 'users',
 'utilities',
 'virtualization',
 'drf_yasg')
Installed Middleware:
('debug_toolbar.middleware.DebugToolbarMiddleware',
 'corsheaders.middleware.CorsMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'django.middleware.security.SecurityMiddleware',
 'utilities.middleware.ExceptionHandlingMiddleware',
 'utilities.middleware.LoginRequiredMiddleware',
 'utilities.middleware.APIVersionMiddleware')



Traceback:

File "/opt/venvs/netbox/local/lib/python2.7/site-packages/django/core/handlers/exception.py" in inner
  41.             response = get_response(request)

File "/opt/venvs/netbox/local/lib/python2.7/site-packages/django/core/handlers/base.py" in _get_response
  187.                 response = self.process_exception_by_middleware(e, request)

File "/opt/venvs/netbox/local/lib/python2.7/site-packages/django/core/handlers/base.py" in _get_response
  185.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/opt/venvs/netbox/local/lib/python2.7/site-packages/django/views/generic/base.py" in view
  68.             return self.dispatch(request, *args, **kwargs)

File "/opt/venvs/netbox/local/lib/python2.7/site-packages/django/contrib/auth/mixins.py" in dispatch
  92.         return super(PermissionRequiredMixin, self).dispatch(request, *args, **kwargs)

File "/opt/venvs/netbox/local/lib/python2.7/site-packages/django/views/generic/base.py" in dispatch
  88.         return handler(request, *args, **kwargs)

File "/opt/netbox/netbox/utilities/views.py" in get
  179.         form = self.model_form(instance=obj, initial=initial_data)

File "/opt/netbox/netbox/dcim/forms.py" in __init__
  1784.             vlan_choices.append((parent.site.name, [(vlan.pk, vlan) for vlan in site_vlans]))

Exception Type: AttributeError at /netbox/dcim/interfaces/447/assign-vlans/
Exception Value: 'NoneType' object has no attribute 'name'