VLAN filtering with VLAN groups

[CTV-2023]

NetBox version

v3.6.2

Python version

3.8

Steps to Reproduce

I have vlans associated to a vlan group. This vlan group scope is a site group. Sites A and B are member of this site group
When I create a new prefix associated to site A, I expect vlans from the vlan group to appear. They don't

On demo website :

• Create a vlan group "Test-Group", scope type DCIM > site group. Choose a site group, Headquarters for instance
  

• Create a vlan and associate it with this vlan group
  

• Associate a site to the Headquarters site group, or select one already in it
  

• Try to create a prefix with this site. You won't see the vlan
  

Expected Behavior

When you define a vlan group with site group as a scope, you expect its site members to "inherit" the vlan. I think this part is ok, but you can't select the vlan in prefix creation

Observed Behavior

The vlan is not visible in prefix creation, maybe due to #13721

As a side note, the vlan appears in 802.1q swiching in interfaces for a device member of the site DM-NYC

[jeremystretch]

I think you're correct in calling this out as a side effect of #13721, however I'm not sure it's a bug. The VLAN field is being filtered by a specific site, to which the desired VLAN is not assigned. This is desired behavior under the condition captured in #13721, but under the condition captured here (where the intent is to infer site assignment via the site group).

Maybe the best solution would be to introduce a separate filter e.g. available_at_site (similar to available_on_device) to filter VLANs according to both site and site group assignments.

As a workaround, you can still use the selector button to the right of the field to select any VLAN, regardless of the selected site.

[bandwiches]

Is there a workaround for v3.3.8? I see the same behavior when editing a site prefix where the vlan group is not populating based on the scope unless the vlan group is it's directly scoped to the site itself (not the region or anything else). The selector button does not appear in 3.3.8 as far as I can tell.

[DanSheps]

Blocked by #14538

[jeremystretch]

Unblocking as #14538 has been completed