Fixes #22588: Filter VLANs by Site Group scope when assigning to a prefix

[ascjreddy]

Closes: #22588

When a prefix's scope is set to a Site Group, the VLAN dropdown was showing all VLANs regardless of scope. This PR fixes that by:

1. Adding a get_for_site_group() method to VLANQuerySet that filters VLANs to only those belonging to the VLAN Groups scoped to the specified Site Group (or its ancestors)
2. Adding an available_at_site_group filter to VLANFilterSet that calls this method
3. Updating PrefixForm.__init__ to swap the available_at_site query param for available_at_site_group when the prefix scope is a Site Group

[jeremystretch]

@claude /review Only report on issues of potential concern; we don't need commentary on anything that doesn't require further consideration.

[github-actions]

Claude finished @jeremystretch's task in 2m 21s —— View job

---

Review

• Gather context
• Read changed files
• Analyze for concerns
• Post review

---

Two concerns worth addressing:

---

1. get_for_site_group() omits global VLANs (netbox/ipam/querysets.py:293–306)

Every other get_for_* method includes globally-scoped VLANs (groups with no scope, and standalone VLANs with no group/site). get_for_site_group() does not:

# get_for_site() — includes global VLANs ✓
return self.filter(
    Q(group__in=VLANGroup.objects.filter(q)) |
    Q(site=site) |
    Q(group__scope_id__isnull=True, site__isnull=True) |  # Global group VLANs
    Q(group__isnull=True, site__isnull=True)              # Global VLANs
)

# get_for_site_group() — omits global VLANs ✗
return self.filter(
    Q(group__in=VLANGroup.objects.filter(q))
)

When a prefix is scoped to a site group, globally available VLANs (those not tied to any specific location scope) would not appear in the assignment dropdown. That seems unintentional. Fix this →

---

2. Test uses unsaved SiteGroup instance (netbox/ipam/tests/test_forms.py:34)

site_group = SiteGroup(name='Site Group 1', slug='site-group-1')  # pk=None, not saved
form = PrefixForm(data={
    'scope_type': ContentType.objects.get_for_model(SiteGroup).id,
    'scope': site_group,
})

The test works because it only checks widget attributes and never calls is_valid(), but a saved instance with a real pk would be the expected pattern for model form tests. If the scope field ever validates its value during __init__, this would silently fail.

[ascjreddy]

Hi @arthanson — just wanted to do a friendly follow-up on this PR. The two concerns from the automated review have been addressed (global VLANs added to get_for_site_group() and the test updated to use a saved instance). All checks are passing. Let me know if there's anything else you'd like me to look at!

[arthanson]

Thanks @ascjreddy I'd request to just add a filterset test for the actual filtering.

The current Test does not exercise get_for_site_group() or the available_at_site_group filter at all. The bug-fixing logic is currently untested.

There's a ready-made pattern to mirror at ipam/tests/test_filtersets.py:2219:

def test_available_at_site(self):
site_id = Site.objects.first().pk
params = {'available_at_site': site_id}
self.assertEqual(self.filterset(params, self.queryset).qs.count(), 5) # 4 scoped + 1 global group + 1 global

Please add an analogous test_available_at_site_group that asserts a Site-Group-scoped VLAN is included while an out-of-scope VLAN is excluded

[ascjreddy]

Hi @arthanson — added test_available_at_site_group mirroring test_available_at_site. All checks passing! Could you check once and let me know if any changes are needed. Thanks!!

[arthanson]

Thanks @ascjreddy !