Closes #12622: Fix assigning VLAN without site to Prefix

[dhenschen]

Summary

This Pull Request enables users to be to select VLANs without a site assignment during creation and bulk import of Prefixes.

This Pull Request addresses issues #12622 and #12619.

Background

Previously, only VLANs assigned to the same site as the prefix were available for selection. However, as it is possible to create VLANs without a site assignment, a subset of selectable VLANs was excluded from the VLAN filter dropdown. Additionally, the import logic did not allow the assignment of a VLAN without a site when a site was specified for the prefix.

Changes

This Pull Request introduces a selector dialog to facilitate filtering and searching for VLANs during assignment. Furthermore, the prefix import code is enhanced to include VLANs without a site assignment in the filtering logic.

Benefits

This change enhances the usability of NetBox by allowing users to assign VLANs with a null site to Prefixes through the UI. Without this modification, Prefixes could only be assigned VLANs from the same site when a site was selected for a Prefix.

Creation Test

1. Import the demo data into NetBox
2. Login into NetBox
3. Import the following VLAN from with the YAML format under IPAM > VLANS > VLANs > Import

vid: 1000
name: management
status: active

4. Create a new Prefix from IPAM > PREFIXES > Prefixes > Add.
5. Set the Prefix field to 10.1.0.0/24
6. Set the Site field to DM-Akron
7. Look for the new management VLAN in the selector dialog. The user can search for a site set to None to easily find the new managment VLAN without a site.

8. Click Create and Verify the new prefix is successfully created

Import Test

Steps for reproducing importing a new Prefix:

1. Import the demo data into NetBox
2. Login to NetBox
3. Import the following VLAN from with the YAML format under IPAM > VLANS > VLANs > Import

vid: 1000
name: management
status: active

4. Import a new Prefix from IPAM > PREFIXES > Prefixes > Import with the following YAML

prefix: 10.1.1.0/24
status: active
site: DM-Akron
vlan: 1000

5. With the changes from this Pull Request, the import successfully assigns a VLAN without a site to a Prefix with a site.

Import Query Tests

I manually tested importing different variations of prefixes to verify the new query in PrefixImportForm. The query results were collected by temporarily adding a print statement to PrefixImportForm.__init__

Import Test 1

prefix: 10.1.1.0/24
status: active
site: DM-Akron
vlan: 1002
vlan_group: JBB-Global

This resulted in the following query:

(AND: (OR: ('site__name', 'DM-Akron'), ('site__name__isnull', True)), ('group__name', 'JBB-Global'))

Import Test 2

prefix: 10.1.1.0/24
status: active
site: DM-Akron
vlan: 1000

This resulted in the following query:

(OR: ('site__name', 'DM-Akron'), ('site__name__isnull', True))

Import Test 3

prefix: 10.1.1.0/24
status: active
vlan: 1000

This resulted in the following query:

(AND: )

Import Test 4

prefix: 10.1.1.0/24
status: active
vlan: 1002
vlan_group: JBB-Global

This resulted in the following query:

(AND: ('group__name', 'JBB-Global'))

[jeremystretch]

LGTM! Thanks for being so thorough @dhenschen!