Allow DiffSyncModel to be present in multiple branches from top_level

[Yoyasp]

Environment

• DiffSync version: 2.0.0

Proposed Functionality

Allow instances of DiffSyncModels to be preset in multiple branches.
This would allow a model to have an optional parent while still syncing all the objects without parents

Use Case

In the Netbox model we can have a VirtualChassis that includes member Device's, but also have Device's that are not part of a VirtualChassis.
If i split up these entities in two DiffSyncModel's and make Device a child of the VirtualChassis i must choose whether i only want to sync the Device's that are part of a VirtualChassis:

• by making the VirtualChassis a top_level entry. This however will ignore all the devices that are not a child of VirtualChassis. Or:
• by making the Device a top_level entry. This however will not create the VirtualChassis.

If i add both VirtualChassis and Device to top_level i get an error that Device's that are a child of VirtualChassis are already created when it wants to add the Device from that top_level entry.

This is exactly the same object so i dont know why it couldnt be possible to just skip over trying to recreate this. This would also be a nicer option than what is suggested in #285 .

[jdrew82]

I've actually done a Nautobot SSoT integration that handled that particular use case. You treat the Device and VirtualChassis as their own top_level objects that are not related via the parent/child relationship construct. You then simply have the VirtualChassis that a Device is a part of as an optional attribute on the Device. Have the VirtualChassis created before the Devices and you can then assign the Device to the VC when it's created.

[Yoyasp]

Thanks for the reply, i guess that would work as a work around. I would have to create the virtual chassis, save their new ids and assign those as a variable on the device.
There would also need to be some rewriting on the feedback of the diffs but thats doable.

Ill see if i can post some code for a future adventurer...

In the mean time, does my request make any sense, or is this just my stupid edge case?

[jdrew82]

I don't think it's a stupid edge case but I don't think it's a case that will fit within how DiffSync works. At this time DiffSync will treat each as it's own object and has no idea of the previously created one so you'd need to write your CRUD operations to handle that particular case.