From 7d9b6dcabf341ef621b8690899d39945317b8a8e Mon Sep 17 00:00:00 2001
From: JensDiemer <git@jensdiemer.de>
Date: Fri, 30 Sep 2022 20:35:01 +0200
Subject: [PATCH] NEW: List number of item on `location` change list

---
 README.md                                     |  1 +
 src/inventory/admin/location.py               | 13 ++++++++-
 .../0013_alter_itemmodel_location.py          | 27 +++++++++++++++++++
 src/inventory/models/item.py                  |  1 +
 4 files changed, 41 insertions(+), 1 deletion(-)
 create mode 100644 src/inventory/migrations/0013_alter_itemmodel_location.py

diff --git a/README.md b/README.md
index 1f8141c..3947e9e 100644
--- a/README.md
+++ b/README.md
@@ -158,6 +158,7 @@ Files are separated into: "/src/" and "/development/"
   * NEW: List all related objects on `item` change page with edit links.
   * Change `parent` and `location` fields on `item` change page to a autocompele field.
   * Add search to `location`
+  * NEW: List number of item on `location` change list
   * tbc
 * [v0.16.0 - 14.09.2022](https://github.com/jedie/PyInventory/compare/v0.15.0...0.16.0)
   * Update requirements
diff --git a/src/inventory/admin/location.py b/src/inventory/admin/location.py
index 1db3901..a321f6c 100644
--- a/src/inventory/admin/location.py
+++ b/src/inventory/admin/location.py
@@ -1,5 +1,6 @@
 from django.conf import settings
 from django.contrib import admin
+from django.db.models import Count
 from django.utils.translation import gettext_lazy as _
 from import_export.admin import ImportExportMixin
 from import_export.resources import ModelResource
@@ -17,13 +18,23 @@ class LocationModelResource(ModelResource):
 
 @admin.register(LocationModel)
 class LocationModelAdmin(ImportExportMixin, BaseUserAdmin):
+    @admin.display(ordering='item_count', description=_('ItemModel.verbose_name_plural'))
+    def item_count(self, obj):
+        return obj.item_count
+
     @admin.display(ordering='path_str', description=_('LocationModel.verbose_name'))
     def location(self, obj):
         text = ' › '.join(obj.path)
         text = ltruncatechars(text, max_length=settings.TREE_PATH_STR_MAX_LENGTH)
         return text
 
-    list_display = ('location', 'create_dt', 'update_dt')
+    def get_queryset(self, request):
+        qs = super().get_queryset(request)
+        qs = qs.annotate(item_count=Count('items'))
+        return qs
+
+    list_display = ('location', 'create_dt', 'update_dt', 'item_count')
+    readonly_fields = ('item_count',)
     list_display_links = ('location',)
     list_filter = (LimitTreeDepthListFilter,)
     search_fields = ('name', 'description', 'tags__name')
diff --git a/src/inventory/migrations/0013_alter_itemmodel_location.py b/src/inventory/migrations/0013_alter_itemmodel_location.py
new file mode 100644
index 0000000..ec1eba4
--- /dev/null
+++ b/src/inventory/migrations/0013_alter_itemmodel_location.py
@@ -0,0 +1,27 @@
+# Generated by Django 3.2.15 on 2022-09-30 18:30
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('inventory', '0012_parent_tree2'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='itemmodel',
+            name='location',
+            field=models.ForeignKey(
+                blank=True,
+                help_text='ItemModel.location.help_text',
+                null=True,
+                on_delete=django.db.models.deletion.SET_NULL,
+                related_name='items',
+                to='inventory.locationmodel',
+                verbose_name='ItemModel.location.verbose_name',
+            ),
+        ),
+    ]
diff --git a/src/inventory/models/item.py b/src/inventory/models/item.py
index b23f9b7..92ec12c 100644
--- a/src/inventory/models/item.py
+++ b/src/inventory/models/item.py
@@ -60,6 +60,7 @@ class ItemModel(BaseParentTreeModel, VersionProtectBaseModel):
     location = models.ForeignKey(
         'inventory.LocationModel',
         blank=True, null=True, on_delete=models.SET_NULL,
+        related_name='items',
         verbose_name=_('ItemModel.location.verbose_name'),
         help_text=_('ItemModel.location.help_text')
     )