Fixes #11460 - Fix unterminated cable exception when editing cable

[DanSheps]

Fixes: #11460 - Fix unterminated cable exception when editing cable

• Fixes the exception when a single cable is not present
• Fixes the exception when both cables aren't present (but does not allow user to proceed)

[DanSheps]

There are other options here for this, right now, this is the path of least resistance without a re-work of the form rendering logic to only partially render specific fields.

Another caveat, for some reason <button> does not send in the param for a hx-get so it requires the get url to be specified, so there isn't an easy way to account for both type being missing

[jeremystretch]

Nice work @DanSheps. However, as this is an open bug in v3.7 we need to fix it in the develop branch (which shouldn't require much change).

If you haven't already, look at how we handle type selection for remote data sources dynamically; we probably want to follow the same pattern here.

[DanSheps]

Updated to develop but I also switched around the rending a bit. Instead of using the hacky method I was using and pulling down the full page as an HTMX and then selecting I did the following:

1. Modify netbox/views/generic/object_views.py to have an htmx_template_name attribute for the ObjectEditView.
2. Defaulted that to the regular htmx form (htmx/form.html)
3. Overrode the htmx_template_name in the CableEditView
4. Broke the form (dcim/cable_edit.html) out into an new file in a new "htmx" folder (form is at dcim/htmx/cable_edit.html)
5. Changed the htmx request around slightly

I was thinking about this last night, I like it more because it is extendable and I think easier, just wasn't sure which way to go.

[arthanson]

@DanSheps the edit form comes up, but if you just select save without any changes an exception is thrown:

 File "/Users/ahanson/dev/work/netbox/netbox/utilities/forms/mixins.py", line 55, in is_valid
    is_valid = super().is_valid()
  File "/Users/ahanson/dev/work/netbox/venv/lib/python3.10/site-packages/django/forms/forms.py", line 201, in is_valid
    return self.is_bound and not self.errors
  File "/Users/ahanson/dev/work/netbox/venv/lib/python3.10/site-packages/django/forms/forms.py", line 196, in errors
    self.full_clean()
  File "/Users/ahanson/dev/work/netbox/venv/lib/python3.10/site-packages/django/forms/forms.py", line 434, in full_clean
    self._clean_form()
  File "/Users/ahanson/dev/work/netbox/venv/lib/python3.10/site-packages/django/forms/forms.py", line 455, in _clean_form
    cleaned_data = self.clean()
  File "/Users/ahanson/dev/work/netbox/netbox/dcim/forms/connections.py", line 103, in clean
    self.instance.a_terminations = self.cleaned_data['a_terminations']
KeyError: 'a_terminations'

[DanSheps]

Thanks Arthur, didn't think to check the next step. Will try and figure out something for that.

[arthanson]

@jeremystretch looks like your changes fixed the issue I had previously

[arthanson]

One weirdness - go to edit a cable and click the delete 'x' next to the Type in the "B Side", the form auto-refreshes and any Type, device and interface are reset. You can see it better by first deleting interface, then when you delete Type interface and Type will be reset back.

[jeremystretch]

This implementation isn't quite perfect, but it does at least resolve #11460 without (AFAICT) breaking any existing functionality. I'm going to merge this as-is to resolve the immediate issues, and we can iterate on improvements separately from there.