Deleting git repository used for backup config causes AttributeError

[pke11y]

Environment

• Python version: 3.7.10
• Nautobot version: 1.0.0
• nautobot-golden-config version: 1.0.0 (develop branch - using dev env)

Steps to Reproduce

1. Create git repository on the UI at Extensibility -> Git Repository for config_context and backup_config
2. Go to GoldenConfig Settings and configure backup path pointing to the newly created git repository
3. Delete the newly created repository using the UI at Extensibility -> Git Repository
4. Go back to the GoldenConfig Settings

Expected Behavior

Can view and reconfigure the settings for the GoldenConfig.

Observed Behavior

AttributeError raised as below.

Environment:


Request Method: GET
Request URL: http://147.75.194.238:8080/plugins/golden-config/setting/

Django Version: 3.1.8
Python Version: 3.7.10
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.humanize',
 'cacheops',
 'corsheaders',
 'django_filters',
 'django_tables2',
 'django_prometheus',
 'mptt',
 'rest_framework',
 'social_django',
 'taggit',
 'timezone_field',
 'nautobot.core',
 'nautobot.circuits',
 'nautobot.dcim',
 'nautobot.ipam',
 'nautobot.extras',
 'nautobot.tenancy',
 'nautobot.users',
 'nautobot.utilities',
 'nautobot.virtualization',
 'django_rq',
 'drf_yasg',
 'graphene_django',
 'debug_toolbar',
 'nautobot_plugin_nornir.NornirConfig',
 'nautobot_golden_config.GoldenConfig',
 'nautobot_netbox_importer.NautobotNetboxImporterConfig']
Installed Middleware:
['debug_toolbar.middleware.DebugToolbarMiddleware',
 'django_prometheus.middleware.PrometheusBeforeMiddleware',
 'corsheaders.middleware.CorsMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'django.middleware.security.SecurityMiddleware',
 'nautobot.core.middleware.ExceptionHandlingMiddleware',
 'nautobot.core.middleware.RemoteUserMiddleware',
 'nautobot.core.middleware.ExternalAuthMiddleware',
 'nautobot.core.middleware.APIVersionMiddleware',
 'nautobot.core.middleware.ObjectChangeMiddleware',
 'django_prometheus.middleware.PrometheusAfterMiddleware']


Template error:
In template /usr/local/lib/python3.7/site-packages/nautobot/core/templates/base.html, error at line 27
   'NoneType' object has no attribute '_meta'
   17 :           href="{% static 'select2-4.0.13/dist/css/select2.min.css' %}"
   18 :           onerror="window.location='{% url 'media_failure' %}?filename=select2-4.0.13/dist/css/select2.min.css'">
   19 :     <link rel="stylesheet"
   20 :           href="{% static 'select2-bootstrap-0.1.0-beta.10/select2-bootstrap.min.css' %}"
   21 :           onerror="window.location='{% url 'media_failure' %}?filename=select2-bootstrap-0.1.0-beta.10/select2-bootstrap.min.css'">
   22 :     <link rel="stylesheet"
   23 :           href="{% static 'flatpickr-4.6.3/themes/light.css' %}"
   24 :           onerror="window.location='{% url 'media_failure' %}?filename=flatpickr-4.6.3/themes/light.css'">
   25 :     <link rel="stylesheet"
   26 :           href="{% static 'css/base.css' %}?v{{ settings.VERSION }}"
   27 :           onerro r="window.location='{% ur l 'media_failure' %}?filename=css/base.css'">
   28 :     <link rel="apple-touch-icon" sizes="180x180" href="{% static 'img/nautobot_icon_180x180.png' %}">
   29 :     <link rel="icon" type="image/png" sizes="32x32" href="{% static 'img/nautobot_icon_32x32.png' %}">
   30 :     <link rel="icon" type="image/png" sizes="16x16" href="{% static 'img/nautobot_icon_16x16.png' %}">
   31 :     <link rel="icon" type="image/png" href="{% static 'img/nautobot_icon_192x192.png' %}" sizes="192x192">
   32 :     <link rel="mask-icon" href="{% static 'img/nautobot_icon_monochrome.svg' %}" color="#0097ff">
   33 :     <link rel="shortcut icon" href="{% static 'img/favicon.ico' %}">
   34 :     <meta name="msapplication-TileColor" content="#2d89ef">
   35 :     <meta name="theme-color" content="#ffffff">
   36 :     <meta charset="UTF-8">
   37 :     <meta name="viewport" content="initial-scale=1, maximum-scale=1, user-scalable=no, width=device-width">


Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/django/core/handlers/exception.py", line 47, in inner
    response = get_response(request)
  File "/usr/local/lib/python3.7/site-packages/django/core/handlers/base.py", line 181, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/usr/local/lib/python3.7/site-packages/django/views/generic/base.py", line 70, in view
    return self.dispatch(request, *args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/nautobot/utilities/views.py", line 94, in dispatch
    return super().dispatch(request, *args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/django/views/generic/base.py", line 98, in dispatch
    return handler(request, *args, **kwargs)
  File "/source/nautobot_golden_config/views.py", line 679, in get
    **self.get_extra_context(request, instance),
  File "/usr/local/lib/python3.7/site-packages/django/shortcuts.py", line 19, in render
    content = loader.render_to_string(template_name, context, request, using=using)
  File "/usr/local/lib/python3.7/site-packages/django/template/loader.py", line 62, in render_to_string
    return template.render(context, request)
  File "/usr/local/lib/python3.7/site-packages/django/template/backends/django.py", line 61, in render
    return self.template.render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 170, in render
    return self._render(context)
  File "/usr/local/lib/python3.7/site-packages/django/test/utils.py", line 96, in instrumented_test_render
    return self.nodelist.render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 938, in render
    bit = node.render_annotated(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 905, in render_annotated
    return self.render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/loader_tags.py", line 150, in render
    return compiled_parent._render(context)
  File "/usr/local/lib/python3.7/site-packages/django/test/utils.py", line 96, in instrumented_test_render
    return self.nodelist.render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 938, in render
    bit = node.render_annotated(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 905, in render_annotated
    return self.render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/loader_tags.py", line 62, in render
    result = block.nodelist.render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 938, in render
    bit = node.render_annotated(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/base.py", line 905, in render_annotated
    return self.render(context)
  File "/usr/local/lib/python3.7/site-packages/django/template/library.py", line 192, in render
    output = self.func(*resolved_args, **resolved_kwargs)
  File "/usr/local/lib/python3.7/site-packages/nautobot/extras/templatetags/custom_links.py", line 30, in custom_links
    content_type = ContentType.objects.get_for_model(obj)
  File "/usr/local/lib/python3.7/site-packages/django/contrib/contenttypes/models.py", line 40, in get_for_model
    opts = self._get_opts(model, for_concrete_model)
  File "/usr/local/lib/python3.7/site-packages/django/contrib/contenttypes/models.py", line 27, in _get_opts
    model = model._meta.concrete_model

Exception Type: AttributeError at /plugins/golden-config/setting/
Exception Value: 'NoneType' object has no attribute '_meta'

[pke11y]

It seems to delete the entry from the goldenconfigsetting table

[jeffkala]

Will mention a temporary workaround:
Manually go into nbshell and create an object.

>>> from nautobot_golden_config.models import GoldenConfigSetting
>>>
>>> GoldenConfigSetting.objects.all()
<RestrictedQuerySet []>
>>>
>>> GoldenConfigSetting.objects.create()
<GoldenConfigSetting: Golden Config Settings>
>>>
>>> GoldenConfigSetting.objects.all()
<RestrictedQuerySet [<GoldenConfigSetting: Golden Config Settings>]>

[jeffkala]

Looks to be related to this in core.
https://github.com/nautobot/nautobot/blob/70b8b15a0702cfabadd3335e5471e19c39983e15/nautobot/extras/models/datasources.py#L125