Add Tags column and tag filter to Custom Objects tab

- prefetch_related('tags') on each per-field queryset eliminates N+1
  queries; one extra batch query per field regardless of result count
- Tags column renders colored badge(s) via {% tag %} builtin, or — when
  no tags are assigned
- Tag filter dropdown appears when ≥1 linked object has a tag; uses
  ?tag=<slug>, composes with ?q=, ?type=, sort, and pagination
- available_tags collected from unfiltered list (prefetch cache), sorted
  by name; tag_slug added to base_params so sort links preserve the filter
- Clear-filters button and empty-state message now cover tag_slug
- Update README, CHANGELOG, CLAUDE.md

Author: Kani999

CHANGELOG.md

@@ -46,6 +46,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   type-dropdown changes now swap only the table zone in-place, without a full page reload.
   The URL is updated via `pushState` so links remain shareable and the browser back button
   restores the previous filter/page state.
+- **Tags column** — each row in the Custom Objects table now shows the tags assigned to
+  that Custom Object instance as colored badges. Rows with no tags display `—`.
+- **Tag filter dropdown** (`?tag=<slug>`) — a tag dropdown appears in the search bar
+  whenever at least one linked Custom Object has a tag, letting users narrow the table to
+  objects with a specific tag. Tag filtering composes with `?q=`, `?type=`, sort, and
+  pagination. Tags are pre-fetched in bulk (`prefetch_related('tags')`) so there is no
+  N+1 query cost.
 
 ### Fixed
 

CLAUDE.md

@@ -57,12 +57,21 @@ from types import SimpleNamespace
 
 - **`_get_linked_custom_objects(instance)`** — returns a Python `list` of `(obj, field)` tuples
   by querying across multiple dynamic model tables. A single queryset is not possible.
+  Each queryset uses `.prefetch_related('tags')` so tag data is batch-fetched (one extra
+  query per field) and cached on each object instance — no N+1 cost in the template.
 - **`_filter_linked_objects(linked, q)`** — filters that list in Python; case-insensitive
   match against `str(obj)`, `str(field.custom_object_type)`, `str(field)`.
+- **`available_tags`** — collected in the view from `linked_all` (unfiltered) by iterating
+  `_obj.tags.all()` (uses prefetch cache). Deduplicated by slug, sorted by `name.lower()`.
+  Passed to context as `available_tags`; the active tag filter slug is `tag_slug`.
+- **Tag filter** — `tag_slug = request.GET.get('tag', '').strip()`; applied after the type
+  filter by checking `tag_slug in {t.slug for t in obj.tags.all()}` (cache hit, no query).
 - **`EnhancedPaginator(linked, get_paginate_count(request))`** — paginates the filtered list.
   `get_paginate_count` respects `?per_page=`, user prefs, and global `PAGINATE_COUNT`.
 - **`inc/paginator.html`** — pass `htmx=True table=htmx_table` to emit `hx-get` links.
   `htmx_table = SimpleNamespace(htmx_url=request.path, embedded=False)`.
+  The paginator uses `{% querystring request page=p %}` which copies all current GET params
+  (including `?tag=`, `?type=`, `?q=`, etc.) so filter state is preserved across pages.
 - **`htmx_partial(request)`** — returns `True` when the request carries `HX-Request` and
   is not boosted. View returns `custom_objects_tab_partial.html` in that case.
 - The partial wraps everything in `<div id="custom_objects_list" class="htmx-container">`.
@@ -171,6 +180,7 @@ Action buttons and column links use the `perms` templatetag from `utilities.temp
 - [x] 17. Link the Type column to the CustomObjectType detail page (`can_view`-gated)
 - [x] 18. Add HTMX partial rendering (paginator, sort headers, search form, type dropdown)
 - [x] 19. Fix Edit/Delete return URL to redirect back to the Custom Objects tab
+- [x] 20. Add Tags column and tag filter dropdown to the Custom Objects tab
 
 ## Critical Reference Files
 

README.md

@@ -4,8 +4,9 @@ A NetBox 4.5.x plugin that adds a **Custom Objects** tab to standard object deta
 showing any Custom Object instances from the `netbox_custom_objects` plugin that reference
 those objects via OBJECT or MULTIOBJECT fields.
 
-The tab includes **pagination**, **text search**, **column sorting**, and **type filtering**,
-with HTMX-powered partial updates so table interactions don't reload the full page.
+The tab includes **pagination**, **text search**, **column sorting**, **type filtering**,
+and **tag filtering**, with HTMX-powered partial updates so table interactions don't reload
+the full page.
 
 ## Screenshot
 
@@ -100,17 +101,23 @@ results to a single type. Uses the `?type=<slug>` query parameter. The dropdown
 auto-submits on selection and is populated from the types actually present in the
 current result set.
 
+### Tag filter
+A dropdown (shown when at least one linked Custom Object has a tag) lets you narrow
+results to objects with a specific tag. Uses the `?tag=<slug>` query parameter. The
+dropdown auto-submits on selection and is populated from the tags present across the
+full result set. Tag data is pre-fetched in bulk so there is no N+1 query cost.
+
 ### Column sorting
 Clicking the **Type**, **Object**, or **Field** column header sorts the table
 in-memory. A second click on the same header reverses the direction. The active
 column shows an up/down arrow icon. Sort state is preserved when the search form
 is submitted.
 
 ### HTMX / Partial updates
-Pagination clicks, column sort clicks, search form submissions, and type-dropdown
-changes all update the table zone in-place using HTMX — no full page reload. The
-URL is updated via `pushState` so links stay shareable and the browser back button
-returns to the previous filter/page state.
+Pagination clicks, column sort clicks, search form submissions, type-dropdown changes,
+and tag-dropdown changes all update the table zone in-place using HTMX — no full page
+reload. The URL is updated via `pushState` so links stay shareable and the browser back
+button returns to the previous filter/page state.
 
 ### Value column
 Each row includes a **Value** column showing the actual field value on the Custom
@@ -148,6 +155,7 @@ The tab displays:
 | **Object** | Link to the Custom Object instance (sortable) |
 | **Value** | The value stored in the linking field — a link for Object fields, comma-separated links for Multi-Object fields |
 | **Field** | The field that holds the reference (sortable) |
+| **Tags** | Colored tag badges assigned to the Custom Object instance; `—` when none |
 | *(actions)* | Edit and Delete buttons, each shown only when the user has the corresponding permission |
 
 ## Support

netbox_custom_objects_tab/templates/netbox_custom_objects_tab/custom_objects_tab.html

@@ -21,7 +21,7 @@ <h2 class="mb-0">{% trans "Custom Objects" %}</h2>
             <button type="submit" class="btn btn-primary">
               <i class="mdi mdi-magnify"></i>
             </button>
-            {% if q or type_slug %}
+            {% if q or type_slug or tag_slug %}
               <a href="?" class="btn btn-outline-secondary" title="{% trans 'Clear filters' %}">
                 <i class="mdi mdi-close"></i>
               </a>
@@ -46,6 +46,23 @@ <h2 class="mb-0">{% trans "Custom Objects" %}</h2>
               {% endfor %}
             </select>
           {% endif %}
+          {# Tag dropdown — only shown when any object has tags #}
+          {% if available_tags %}
+            <select name="tag"
+                    hx-get="{{ request.path }}"
+                    hx-target="#custom_objects_list"
+                    hx-swap="outerHTML"
+                    hx-push-url="true"
+                    hx-include="closest form"
+                    hx-trigger="change"
+                    class="form-select form-select-sm w-auto"
+                    aria-label="{% trans 'Filter by tag' %}">
+              <option value="">{% trans "All tags" %}</option>
+              {% for t in available_tags %}
+                <option value="{{ t.slug }}"{% if t.slug == tag_slug %} selected{% endif %}>{{ t.name }}</option>
+              {% endfor %}
+            </select>
+          {% endif %}
           {# Preserve sort state and per_page when submitting the search form #}
           {% if sort %}<input type="hidden" name="sort" value="{{ sort }}">{% endif %}
           {% if sort_dir and sort_dir != 'asc' %}<input type="hidden" name="dir" value="{{ sort_dir }}">{% endif %}

netbox_custom_objects_tab/templates/netbox_custom_objects_tab/custom_objects_tab_partial.html

@@ -30,6 +30,7 @@
                 {% if sort_headers.field.icon %}<i class="mdi mdi-{{ sort_headers.field.icon }}"></i>{% endif %}
               </a>
             </th>
+            <th>{% trans "Tags" %}</th>
             <th></th>
           </tr>
         </thead>
@@ -65,6 +66,13 @@
                 {% endif %}
               </td>
               <td>{{ field }}</td>
+              <td>
+                {% for t in obj.tags.all %}
+                  {% tag t %}{% if not forloop.last %} {% endif %}
+                {% empty %}
+                  &mdash;
+                {% endfor %}
+              </td>
               <td class="text-end text-nowrap">
                 {% if request.user|can_change:obj %}
                 <a href="{% url 'plugins:netbox_custom_objects:customobject_edit' pk=obj.pk custom_object_type=obj.custom_object_type.slug %}?return_url={{ return_url|urlencode }}" class="btn btn-yellow" role="button">
@@ -84,7 +92,7 @@
     </div>
   {% else %}
     <div class="card-body text-muted">
-      {% if q or type_slug %}
+      {% if q or type_slug or tag_slug %}
         {% trans "No custom objects match your filters." %}
       {% else %}
         {% trans "No custom objects are linked to this object." %}

netbox_custom_objects_tab/views.py

@@ -52,10 +52,10 @@ def _get_linked_custom_objects(instance):
             continue
 
         if field.type == CustomFieldTypeChoices.TYPE_OBJECT:
-            for obj in model.objects.filter(**{f'{field.name}_id': instance.pk}):
+            for obj in model.objects.filter(**{f'{field.name}_id': instance.pk}).prefetch_related('tags'):
                 results.append((obj, field))
         elif field.type == CustomFieldTypeChoices.TYPE_MULTIOBJECT:
-            for obj in model.objects.filter(**{field.name: instance.pk}):
+            for obj in model.objects.filter(**{field.name: instance.pk}).prefetch_related('tags'):
                 results.append((obj, field))
 
     return results
@@ -197,17 +197,33 @@ def get(self, request, pk):
             # Read filter/sort params
             q = request.GET.get('q', '')
             type_slug = request.GET.get('type', '')
+            tag_slug = request.GET.get('tag', '').strip()
             sort_col = request.GET.get('sort', '')
             sort_dir = request.GET.get('dir', 'asc')
             per_page = request.GET.get('per_page', '')
 
+            # Collect unique tags for the dropdown (always from the unfiltered list)
+            seen_tag_slugs = set()
+            available_tags = []
+            for _obj, _field in linked_all:
+                for t in _obj.tags.all():
+                    if t.slug not in seen_tag_slugs:
+                        seen_tag_slugs.add(t.slug)
+                        available_tags.append(t)
+            available_tags.sort(key=lambda t: t.name.lower())
+
             # Apply filters
             linked = _filter_linked_objects(linked_all, q)
             if type_slug:
                 linked = [
                     (obj, field) for obj, field in linked
                     if field.custom_object_type.slug == type_slug
                 ]
+            if tag_slug:
+                linked = [
+                    (obj, field) for obj, field in linked
+                    if tag_slug in {t.slug for t in obj.tags.all()}
+                ]
 
             # In-memory sort (applied after filters, before pagination)
             if sort_col in _SORT_KEYS:
@@ -232,6 +248,8 @@ def get(self, request, pk):
                 base_params['q'] = q
             if type_slug:
                 base_params['type'] = type_slug
+            if tag_slug:
+                base_params['tag'] = tag_slug
             if per_page:
                 base_params['per_page'] = per_page
             sort_base = urlencode(base_params)
@@ -254,7 +272,9 @@ def get(self, request, pk):
                 'page_rows': page_rows,
                 'q': q,
                 'type_slug': type_slug,
+                'tag_slug': tag_slug,
                 'available_types': available_types,
+                'available_tags': available_tags,
                 'sort': sort_col,
                 'sort_dir': sort_dir,
                 'sort_headers': sort_headers,