Add Add-button on Typed tabs with reverse-reference prefill (closes #9)

Each typed tab now exposes an "Add <Type>" button that links to the native
customobject_add view with the back-reference field pre-populated to the
parent object's PK and return_url set to the current tab path. After saving,
the user lands back on the tab with filters preserved.

When a Custom Object Type has multiple back-reference fields to the same
parent model (e.g. primary_device + backup_device both -> dcim.device),
the button becomes a Bootstrap split-dropdown listing each field. The
button is hidden for users without add_customobject permission.

Implementation:
- New module-level _build_add_links() helper computes URLs from
  (slug, instance_pk, field_infos, return_url). Pure function, fully unit-tested.
- field_infos tuples extended from (name, type) to (name, type, label) so the
  dropdown can show human-readable field labels. Star-unpacking in
  _count_for_type and the queryset filter loop preserves backward compatibility
  with 2-tuple shapes used by existing tests.
- Permission gate uses utilities.permissions.get_permission_for_model, matching
  the pattern used by netbox_custom_objects.tables.CustomObjectActionsColumn.
- field_infos is sorted by field name in register_typed_tabs so the dropdown
  order is deterministic.

Tab placement: top-right of tab content, scoped entirely to typed/tab.html.
Tabs with hide_if_empty=True remain hidden until the first object is created
via the native menu - the button surfaces once the tab is visible.

Bumps version to 2.2.0 (minor, new feature). Test suite extended from 53 to 61
tests covering reverse failure, single/multi field, deduplication, label
fallback, 2-tuple back-compat, and return_url URL-encoding.

Author: Kani999

CHANGELOG.md

@@ -5,6 +5,21 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [2.2.0] - 2026-04-22
+
+### Added
+
+- **Add button on Typed tabs** ([#9](https://github.com/CESNET/netbox-custom-objects-tab/issues/9)) —
+  each Typed tab now shows an "Add *Type*" button (top-right) that opens the native
+  `customobject_add` view with the reverse-reference field pre-filled to the parent
+  object's PK and `return_url` set back to the tab. After saving, the user lands back
+  on the same tab, with any active filters preserved. When a Custom Object Type has
+  multiple fields referencing the same parent model (e.g. `primary_device` and
+  `backup_device` both → Device), the button becomes a split-dropdown listing each
+  field. The button is hidden for users without `add_customobject` permission.
+  Tabs with `hide_if_empty=True` are still hidden until the first object is created
+  via the native menu — subsequent additions can use the new button.
+
 ## [2.1.0] - 2026-03-16
 
 ### Added

netbox_custom_objects_tab/templates/netbox_custom_objects_tab/typed/tab.html

@@ -5,6 +5,34 @@
 {% load i18n %}
 {% block content %}
     {% if table %}
+        {# Add button (single) or split-dropdown (multiple back-reference fields) #}
+        {% if can_add and add_links %}
+            <div class="d-flex justify-content-end mt-2 mb-2">
+                {% if add_links|length == 1 %}
+                    <a href="{{ add_links.0.url }}" class="btn btn-sm btn-primary">
+                        <i class="mdi mdi-plus-thick"></i>
+                        {% blocktrans with label=add_label %}Add {{ label }}{% endblocktrans %}
+                    </a>
+                {% else %}
+                    <div class="btn-group">
+                        <button type="button"
+                                class="btn btn-sm btn-primary dropdown-toggle"
+                                data-bs-toggle="dropdown"
+                                aria-expanded="false">
+                            <i class="mdi mdi-plus-thick"></i>
+                            {% blocktrans with label=add_label %}Add {{ label }}{% endblocktrans %}
+                        </button>
+                        <ul class="dropdown-menu dropdown-menu-end">
+                            {% for link in add_links %}
+                                <li>
+                                    <a class="dropdown-item" href="{{ link.url }}">{% blocktrans with f=link.label %}via {{ f }}{% endblocktrans %}</a>
+                                </li>
+                            {% endfor %}
+                        </ul>
+                    </div>
+                {% endif %}
+            </div>
+        {% endif %}
         <hr class="mt-0 mb-3">
         {# Results / Filters inner tabs #}
         <ul class="nav nav-tabs custom-objects-subtabs mb-3" role="tablist">

netbox_custom_objects_tab/views/typed.py

@@ -1,10 +1,12 @@
 import logging
 from collections import defaultdict
+from urllib.parse import urlencode
 
 from django.contrib.contenttypes.models import ContentType
 from django.db.models import Q
 from django.db.utils import OperationalError, ProgrammingError
 from django.shortcuts import get_object_or_404, render
+from django.urls import NoReverseMatch, reverse
 from django.views.generic import View
 from extras.choices import CustomFieldTypeChoices, CustomFieldUIVisibleChoices
 from netbox.forms import NetBoxModelFilterSetForm
@@ -14,6 +16,7 @@
 from netbox_custom_objects.models import CustomObjectTypeField
 from netbox_custom_objects.tables import CustomObjectTable
 from utilities.forms.fields import TagFilterField
+from utilities.permissions import get_permission_for_model
 from utilities.views import ViewTab, register_model_view
 
 from ._co_common import _CO_BASE_TEMPLATE, _CUSTOM_OBJECTS_APP, _get_base_template  # noqa: F401
@@ -99,10 +102,44 @@ def _build_filterset_form(custom_object_type, dynamic_model):
     )
 
 
+def _build_add_links(custom_object_type_slug, instance_pk, field_infos, return_url):
+    """
+    Build pre-filled "Add" URLs for the native customobject_add view.
+
+    field_infos = list of (field_name, field_type, [label]) for fields referencing the parent.
+    Returns list of {"field_name", "label", "url"} dicts (one per unique field), or [] if URL
+    cannot be reversed (e.g. plugin URL conf not loaded).
+    """
+    try:
+        add_base = reverse(
+            "plugins:netbox_custom_objects:customobject_add",
+            kwargs={"custom_object_type": custom_object_type_slug},
+        )
+    except NoReverseMatch:
+        return []
+
+    links = []
+    seen = set()
+    for field_name, _field_type, *rest in field_infos:
+        if field_name in seen:
+            continue
+        seen.add(field_name)
+        field_label = (rest[0] if rest else field_name) or field_name
+        qs = urlencode({field_name: instance_pk, "return_url": return_url})
+        links.append(
+            {
+                "field_name": field_name,
+                "label": field_label,
+                "url": f"{add_base}?{qs}",
+            }
+        )
+    return links
+
+
 def _count_for_type(custom_object_type, field_infos):
     """
     Return a badge callable for one Custom Object Type.
-    field_infos = list of (field_name, field_type) for fields referencing the parent model.
+    field_infos = list of (field_name, field_type, [label]) for fields referencing the parent model.
     Uses COUNT(*) only. Returns None when 0.
     """
 
@@ -117,7 +154,7 @@ def _badge(instance):
             return None
 
         total = 0
-        for field_name, field_type in field_infos:
+        for field_name, field_type, *_ in field_infos:
             if field_type == CustomFieldTypeChoices.TYPE_OBJECT:
                 total += dynamic_model.objects.filter(**{f"{field_name}_id": instance.pk}).count()
             elif field_type == CustomFieldTypeChoices.TYPE_MULTIOBJECT:
@@ -177,7 +214,7 @@ def get(self, request, pk, **kwargs):
 
             # Build base queryset: union of all field filters for this type
             q_filter = Q()
-            for field_name, field_type in field_infos:
+            for field_name, field_type, *_ in field_infos:
                 if field_type == CustomFieldTypeChoices.TYPE_OBJECT:
                     q_filter |= Q(**{f"{field_name}_id": instance.pk})
                 elif field_type == CustomFieldTypeChoices.TYPE_MULTIOBJECT:
@@ -213,6 +250,16 @@ def get(self, request, pk, **kwargs):
 
             return_url = request.get_full_path()
 
+            # Add-button: link(s) to native CO add view with reverse field pre-filled
+            add_permission = get_permission_for_model(dynamic_model, "add")
+            can_add = request.user.has_perm(add_permission)
+            add_links = _build_add_links(cot.slug, instance.pk, field_infos, return_url) if can_add else []
+
+            try:
+                add_label = cot.get_verbose_name()
+            except AttributeError:
+                add_label = str(cot)
+
             context = {
                 "object": instance,
                 "tab": self.tab,
@@ -223,6 +270,9 @@ def get(self, request, pk, **kwargs):
                 "custom_object_type": cot,
                 "model": dynamic_model,
                 "preferences": preferences,
+                "can_add": can_add,
+                "add_links": add_links,
+                "add_label": add_label,
             }
 
             if request.htmx and not request.htmx.boosted:
@@ -250,16 +300,21 @@ def register_typed_tabs(model_classes, weight):
         ).select_related("custom_object_type")
 
         # Group by (content_type_id, custom_object_type_pk)
-        # -> list of (field_name, field_type)
+        # -> list of (field_name, field_type, field_label)
         ct_cot_fields = defaultdict(list)
         ct_cot_map = {}  # (ct_id, cot_pk) -> CustomObjectType
         for field in all_fields:
             if field.related_object_type_id is None:
                 continue
             key = (field.related_object_type_id, field.custom_object_type_id)
-            ct_cot_fields[key].append((field.name, field.type))
+            label = getattr(field, "label", "") or field.name
+            ct_cot_fields[key].append((field.name, field.type, label))
             ct_cot_map[key] = field.custom_object_type
 
+        # Sort each group by field name for deterministic Add-button order
+        for key in ct_cot_fields:
+            ct_cot_fields[key].sort(key=lambda f: f[0])
+
         # Build a set of content_type_ids we care about
         model_ct_map = {}  # content_type_id -> model_class
         for model_class in model_classes:

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "netbox-custom-objects-tab"
-version = "2.1.1"
+version = "2.2.0"
 description = "NetBox plugin that adds a Custom Objects tab to object detail pages"
 readme = "README.md"
 requires-python = ">=3.12"

tests/conftest.py

@@ -4,6 +4,7 @@
 This file is loaded by pytest before collection, ensuring mocks exist before
 plugin modules are imported.
 """
+
 import sys
 from types import ModuleType
 from unittest.mock import MagicMock
@@ -16,10 +17,10 @@ def _mock(dotted_name, **attrs):
     Create a mock module at `dotted_name` and register it (and any missing
     parent packages) in sys.modules.  Does NOT overwrite already-present entries.
     """
-    parts = dotted_name.split('.')
+    parts = dotted_name.split(".")
     # Ensure every parent package exists
     for i in range(1, len(parts)):
-        parent = '.'.join(parts[:i])
+        parent = ".".join(parts[:i])
         if parent not in sys.modules:
             sys.modules[parent] = ModuleType(parent)
 
@@ -34,7 +35,7 @@ def _mock(dotted_name, **attrs):
 
     # Attach as attribute on parent so `from parent import child` works
     if len(parts) > 1:
-        parent_mod = sys.modules['.'.join(parts[:-1])]
+        parent_mod = sys.modules[".".join(parts[:-1])]
         setattr(parent_mod, parts[-1], mod)
 
     return mod
@@ -45,41 +46,43 @@ def _mock(dotted_name, **attrs):
 # comparisons inside views.py work correctly when we set field.type = TYPE_OBJECT.
 # ---------------------------------------------------------------------------
 class _CustomFieldTypeChoices:
-    TYPE_OBJECT = 'object'
-    TYPE_MULTIOBJECT = 'multiobject'
-    TYPE_TEXT = 'text'
-    TYPE_LONGTEXT = 'longtext'
+    TYPE_OBJECT = "object"
+    TYPE_MULTIOBJECT = "multiobject"
+    TYPE_TEXT = "text"
+    TYPE_LONGTEXT = "longtext"
 
 
 class _CustomFieldUIVisibleChoices:
-    HIDDEN = 'hidden'
+    HIDDEN = "hidden"
 
 
 # --- netbox.* ---
-_mock('netbox')
-_mock('netbox.registry', registry={"views": {}})
-_mock('netbox.plugins',
-      PluginConfig=type('PluginConfig', (), {}),
-      get_plugin_config=MagicMock(return_value=[]))
-_NetBoxModelFilterSetForm = type('NetBoxModelFilterSetForm', (), {})
-_mock('netbox.forms', NetBoxModelFilterSetForm=_NetBoxModelFilterSetForm)
-_mock('netbox.forms.mixins', SavedFiltersMixin=type('SavedFiltersMixin', (), {}))
+_mock("netbox")
+_mock("netbox.registry", registry={"views": {}})
+_mock("netbox.plugins", PluginConfig=type("PluginConfig", (), {}), get_plugin_config=MagicMock(return_value=[]))
+_NetBoxModelFilterSetForm = type("NetBoxModelFilterSetForm", (), {})
+_mock("netbox.forms", NetBoxModelFilterSetForm=_NetBoxModelFilterSetForm)
+_mock("netbox.forms.mixins", SavedFiltersMixin=type("SavedFiltersMixin", (), {}))
 
 # --- extras.* ---
-_mock('extras')
+_mock("extras")
 _mock(
-    'extras.choices',
+    "extras.choices",
     CustomFieldTypeChoices=_CustomFieldTypeChoices,
     CustomFieldUIVisibleChoices=_CustomFieldUIVisibleChoices,
 )
 
 # --- utilities.* ---
-_mock('utilities')
-_mock('utilities.views', ViewTab=MagicMock(), register_model_view=MagicMock())
-_mock('utilities.paginator', EnhancedPaginator=MagicMock(), get_paginate_count=MagicMock())
-_mock('utilities.htmx', htmx_partial=MagicMock())
-_mock('utilities.forms')
-_mock('utilities.forms.fields', TagFilterField=MagicMock())
+_mock("utilities")
+_mock("utilities.views", ViewTab=MagicMock(), register_model_view=MagicMock())
+_mock("utilities.paginator", EnhancedPaginator=MagicMock(), get_paginate_count=MagicMock())
+_mock("utilities.htmx", htmx_partial=MagicMock())
+_mock("utilities.forms")
+_mock("utilities.forms.fields", TagFilterField=MagicMock())
+_mock(
+    "utilities.permissions",
+    get_permission_for_model=MagicMock(return_value="netbox_custom_objects.add_customobject"),
+)
 
 
 class _FakeBaseTable(_tables2.Table):
@@ -119,12 +122,12 @@ def _set_columns(self, selected_columns):
         ]
 
 
-_mock('netbox.tables', BaseTable=_FakeBaseTable)
+_mock("netbox.tables", BaseTable=_FakeBaseTable)
 
 # --- netbox_custom_objects.* ---
-_mock('netbox_custom_objects')
-_mock('netbox_custom_objects.models', CustomObjectTypeField=MagicMock())
-_mock('netbox_custom_objects.field_types', FIELD_TYPE_CLASS={})
-_mock('netbox_custom_objects.filtersets', get_filterset_class=MagicMock())
-_CustomObjectTable = type('CustomObjectTable', (), {})
-_mock('netbox_custom_objects.tables', CustomObjectTable=_CustomObjectTable)
+_mock("netbox_custom_objects")
+_mock("netbox_custom_objects.models", CustomObjectTypeField=MagicMock())
+_mock("netbox_custom_objects.field_types", FIELD_TYPE_CLASS={})
+_mock("netbox_custom_objects.filtersets", get_filterset_class=MagicMock())
+_CustomObjectTable = type("CustomObjectTable", (), {})
+_mock("netbox_custom_objects.tables", CustomObjectTable=_CustomObjectTable)

tests/settings.py

@@ -2,15 +2,15 @@
 # Only the packages needed to make ContentType importable are included.
 
 INSTALLED_APPS = [
-    'django.contrib.contenttypes',
-    'django.contrib.auth',
+    "django.contrib.contenttypes",
+    "django.contrib.auth",
 ]
 
 DATABASES = {
-    'default': {
-        'ENGINE': 'django.db.backends.sqlite3',
-        'NAME': ':memory:',
+    "default": {
+        "ENGINE": "django.db.backends.sqlite3",
+        "NAME": ":memory:",
     }
 }
 
-DEFAULT_AUTO_FIELD = 'django.db.models.BigAutoField'
+DEFAULT_AUTO_FIELD = "django.db.models.BigAutoField"