Closes #21929: Eliminate redundant object view templates

[jeremystretch]

Closes: #21929

• Introduce the get_default_template() utility function to safely resolve the conventional template name for a model
• Update several feature views to employ get_default_template()
• Delete all "empty" object view templates
• Update the applicable view classes to render generic/object.html directly

[jeremystretch]

@claude /review Highlight any inconsistencies or gaps

[claude]

Claude finished @jeremystretch's task in 7m 6s —— View job

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Code Review: Eliminate Redundant Object View Templates

• Read changed view files
• Analyze template deletions
• Check for inconsistencies or gaps
• Post review

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Overview

This PR deletes "empty" model-specific templates that only contained {% extends 'generic/object.html' %} and updates the corresponding view classes to set template_name = 'generic/object.html' explicitly. A third commit introduces get_default_template() to safely resolve the base template for feature views (changelog, journal, image-attachments, jobs). The overall approach is sound, but there's one real bug and a few gaps worth addressing.

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Bug: ObjectContactsView will fail for L2VPN

File: netbox/netbox/views/generic/object_views.py, line 166

'base_template': f'{instance._meta.app_label}/{instance._meta.model_name}.html',

ObjectChildrenView.get() hard-codes base_template using the model's app label and model name. generic/object_children.html then does {% extends base_template %}, so if the template file doesn't exist the page will raise TemplateDoesNotExist.

The get_default_template() helper was correctly applied to ObjectChangeLogView, ObjectImageAttachmentsView, ObjectJournalView, and ObjectJobsView in feature_views.py — but not to ObjectChildrenView, which is the base class for ObjectContactsView.

L2VPN uses ContactsMixin, meaning it gets a Contacts tab auto-registered via register_model_view. Its template vpn/l2vpn.html was deleted in this PR. Navigating to the Contacts tab of any L2VPN will now raise TemplateDoesNotExist: vpn/l2vpn.html.

Fix: Replace line 166 in object_views.py with get_default_template(instance):

'base_template': get_default_template(instance),

Fix this →

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Gap: Inconsistent application of get_default_template()

get_default_template() was applied to 4 of the 5 auto-registered feature views but not to the contacts view path (ObjectChildrenView). The fix above closes this gap. It's worth double-checking whether any other ObjectChildrenView subclasses with a hard-coded base_template override could have a similar issue.

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Minor observations

• users/group.html, users/user.html, users/ownergroup.html only override {% block subtitle %}{% endblock %} to suppress the created/last-updated metadata shown by generic/object.html. These were correctly left alone since they have meaningful content.
• circuits app views have no template_name set and rely on model-specific templates that still exist with real content (breadcrumbs, extra controls). Not a problem; correctly excluded from this PR.
• get_default_template() performance: The function calls get_template() (which hits Django's template loader cache) on every request for changelog/journal/etc. tabs. With the cached template loader in production this is fine; in DEBUG mode it's a minor filesystem hit per request. Not a blocker, just worth noting.
• No direct unit tests for get_default_template(). The function is simple and implicitly tested by any view test covering the affected tabs, but an explicit unit test would be a nice safeguard.

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Summary: One real bug (L2VPN Contacts tab will raise TemplateDoesNotExist) due to ObjectChildrenView.get() not being updated to use get_default_template(). The rest of the cleanup is consistent and well-structured.

[jeremystretch]

Fixed the above bug concerning ObjectChildrenView

[arthanson]

Can we remove all the assignments of template_name = 'generic/object.html' and just put it into netbox.views.generic.object_views.ObjectView it should still work the same and would be consistent with the other Generic object views and less boilerplate with the new get_default_template

Also the doc comment on netbox.views.generic.object_views.ObjectView needs to be changed, currently

    Note: If `template_name` is not specified, it will be determined automatically based on the queryset model.

With the new logic the is reversed, it will always try to check if the {app}/{model} template exists first and then fallback to the template_name.

[jeremystretch]

@arthanson That would potentially break plugin usage. We'll probably head that way eventually, but for now we have to be very careful not to alter the base view's behavior.