Container: prevent parent infinite loop

2 files changed, 36 insertions, 1 deletions

diff --git a/archaeological_warehouse/models.py b/archaeological_warehouse/models.py
index a72d5a214..add786012 100644
--- a/archaeological_warehouse/models.py
+++ b/archaeological_warehouse/models.py
@@ -1274,6 +1274,22 @@ class Container(
     def _get_base_image_path(self):
         return self.location._get_base_image_path() + "/" + self.external_id
 
+    def _prevent_parent_infinite_loop(self) -> bool:
+        """
+        Check there is no infinite loop in parents. If a loop is detected, set the
+        parent to null.
+        :return: True if parent has been changed
+        """
+        parent = self.parent
+        parents = []
+        while parent:
+            if parent.id in parents:
+                self.parent = None  # break the loop arbitrary
+                return True
+            parents.append(parent.id)
+            parent = parent.parent
+        return False
+
     @classmethod
     def _change_child_location(cls, parent):
         for child in (
@@ -1742,9 +1758,10 @@ class Container(
         self.pre_save()
         super(Container, self).save(*args, **kwargs)
         self._change_child_location(self)
+        updated = False
+        updated += self._prevent_parent_infinite_loop()
         self._update_warehouse_max_division()
 
-        updated = False
         updated += self._calculate_weight()
 
         if not self.index and not self.container_type.stationary:
diff --git a/archaeological_warehouse/tests.py b/archaeological_warehouse/tests.py
index 347382e75..4e6ca9dd9 100644
--- a/archaeological_warehouse/tests.py
+++ b/archaeological_warehouse/tests.py
@@ -1142,6 +1142,24 @@ class ContainerTest(FindInit, TestCase):
             "|".join(sorted([mat0.code, mat1.code, mat2.code])),
         )
 
+    def test_prevent_parent_infinite_loop(self):
+        ct = models.ContainerType.objects.all()[0]
+        container_1 = models.Container.objects.create(
+            reference="Test 1", location=self.main_warehouse, container_type=ct
+        )
+        container_2 = models.Container.objects.create(
+            reference="Test 2", location=self.main_warehouse, container_type=ct,
+            parent=container_1
+        )
+        container_3 = models.Container.objects.create(
+            reference="Test 2", location=self.main_warehouse, container_type=ct,
+            parent=container_2
+        )
+        container_1.parent = container_3
+        container_1.save()
+        self.assertIsNone(models.Container.objects.get(pk=container_1.pk).parent)
+
+
     def test_calculated_weight(self):
         self.create_finds()
         self.create_finds()