From 16e00962f5f5b46cc09910ff0be2a5a5ee4ebf1e Mon Sep 17 00:00:00 2001
From: Oliver <oliver.henry.walters@gmail.com>
Date: Tue, 28 Sep 2021 10:14:25 +1000
Subject: [PATCH 1/4] Override the "delete" behaviour for StockItem API

- Mark for deletion instead of calling database delete
- Returns (almost) instantly instead of hanging
- Much better UI experience when performing bulk delete operations
---
 InvenTree/stock/api.py | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/InvenTree/stock/api.py b/InvenTree/stock/api.py
index 017457f600..eaa65dd763 100644
--- a/InvenTree/stock/api.py
+++ b/InvenTree/stock/api.py
@@ -109,6 +109,17 @@ class StockDetail(generics.RetrieveUpdateDestroyAPIView):
 
         return super().update(request, *args, **kwargs)
 
+    def perform_destroy(self, instance):
+        """
+        Instead of "deleting" the StockItem
+        (which may take a long time)
+        we instead schedule it for deletion at a later date.
+        
+        The background worker will delete these in the future
+        """
+
+        instance.mark_for_deletion()
+
 
 class StockAdjust(APIView):
     """

From 2d9ca7c1b654062d804c7ddcda52b6ac08c09cf5 Mon Sep 17 00:00:00 2001
From: Oliver <oliver.henry.walters@gmail.com>
Date: Tue, 28 Sep 2021 10:36:01 +1000
Subject: [PATCH 2/4] Do not rebuild the entire StockItem tree every time a
 single StockItem is deleted!

---
 InvenTree/stock/models.py | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/InvenTree/stock/models.py b/InvenTree/stock/models.py
index 3344dec0eb..1372e63406 100644
--- a/InvenTree/stock/models.py
+++ b/InvenTree/stock/models.py
@@ -1650,9 +1650,6 @@ def before_delete_stock_item(sender, instance, using, **kwargs):
         child.parent = instance.parent
         child.save()
 
-    # Rebuild the MPTT tree
-    StockItem.objects.rebuild()
-
 
 class StockItemAttachment(InvenTreeAttachment):
     """

From d9704f4123e1cbe5f840bd7964ec8eb12cd7854a Mon Sep 17 00:00:00 2001
From: Oliver <oliver.henry.walters@gmail.com>
Date: Tue, 28 Sep 2021 10:41:03 +1000
Subject: [PATCH 3/4] Add unit test for deleting stock items via the API

---
 InvenTree/stock/test_api.py | 57 +++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/InvenTree/stock/test_api.py b/InvenTree/stock/test_api.py
index 619b4444d7..3b6facc9a6 100644
--- a/InvenTree/stock/test_api.py
+++ b/InvenTree/stock/test_api.py
@@ -18,6 +18,7 @@ from InvenTree.api_tester import InvenTreeAPITestCase
 from common.models import InvenTreeSetting
 
 from .models import StockItem, StockLocation
+from .tasks import delete_old_stock_items
 
 
 class StockAPITestCase(InvenTreeAPITestCase):
@@ -37,6 +38,7 @@ class StockAPITestCase(InvenTreeAPITestCase):
         'stock.add',
         'stock_location.change',
         'stock_location.add',
+        'stock.delete',
     ]
 
     def setUp(self):
@@ -591,6 +593,61 @@ class StocktakeTest(StockAPITestCase):
         self.assertContains(response, 'Valid location must be specified', status_code=status.HTTP_400_BAD_REQUEST)
 
 
+class StockItemDeletionTest(StockAPITestCase):
+    """
+    Tests for stock item deletion via the API
+    """
+
+    def test_delete(self):
+
+        # Check there are no stock items scheduled for deletion
+        self.assertEqual(
+            StockItem.objects.filter(scheduled_for_deletion=True).count(),
+            0
+        )
+
+        # Create and then delete a bunch of stock items
+        for idx in range(10):
+
+            # Create new StockItem via the API
+            response = self.post(
+                reverse('api-stock-list'),
+                {
+                    'part': 1,
+                    'location': 1,
+                    'quantity': idx,
+                },
+                expected_code=201
+            )
+
+            pk = response.data['pk']
+
+            item = StockItem.objects.get(pk=pk)
+
+            self.assertFalse(item.scheduled_for_deletion)
+
+            url = reverse('api-stock-detail', kwargs={'pk': pk})
+
+            # Request deletion via the API
+            self.delete(
+                reverse('api-stock-detail', kwargs={'pk': pk}),
+                expected_code=204
+            )
+
+        # There should be 100x StockItem objects marked for deletion
+        self.assertEqual(
+            StockItem.objects.filter(scheduled_for_deletion=True).count(),
+            10
+        )
+
+        # Perform the actual delete (will take some time)
+        delete_old_stock_items()
+
+        self.assertEqual(
+            StockItem.objects.filter(scheduled_for_deletion=True).count(),
+            0
+        )
+
 class StockTestResultTest(StockAPITestCase):
 
     def get_url(self):

From 62e62af5fc08cde8bd7b9102d6685c5a2194e80e Mon Sep 17 00:00:00 2001
From: Oliver <oliver.henry.walters@gmail.com>
Date: Tue, 28 Sep 2021 10:41:30 +1000
Subject: [PATCH 4/4] PEP style fixes

---
 InvenTree/stock/test_api.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/InvenTree/stock/test_api.py b/InvenTree/stock/test_api.py
index 3b6facc9a6..21c355fae2 100644
--- a/InvenTree/stock/test_api.py
+++ b/InvenTree/stock/test_api.py
@@ -626,8 +626,6 @@ class StockItemDeletionTest(StockAPITestCase):
 
             self.assertFalse(item.scheduled_for_deletion)
 
-            url = reverse('api-stock-detail', kwargs={'pk': pk})
-
             # Request deletion via the API
             self.delete(
                 reverse('api-stock-detail', kwargs={'pk': pk}),
@@ -648,6 +646,7 @@ class StockItemDeletionTest(StockAPITestCase):
             0
         )
 
+
 class StockTestResultTest(StockAPITestCase):
 
     def get_url(self):