Fixed SubnetDivisionIndex foreign keys saved as NULL

openwisp_controller/subnet_division/rule_types/base.py

@@ -256,7 +256,7 @@ def create_subnets(config, division_rule, max_subnet, generated_indexes):
             generated_indexes.append(
                 SubnetDivisionIndex(
                     keyword=f"{division_rule.label}_subnet{subnet_id}",
-                    subnet_id=subnet_obj.id,
+                    subnet=subnet_obj,
                     rule_id=division_rule.id,
                     config=config,
                 )
@@ -294,8 +294,8 @@ def create_ips(config, division_rule, generated_subnets, generated_indexes):
                 generated_indexes.append(
                     SubnetDivisionIndex(
                         keyword=f"{subnet_obj.name}_ip{keyword_index}",
-                        subnet_id=subnet_obj.id,
-                        ip_id=ip_obj.id,
+                        subnet=subnet_obj,
+                        ip=ip_obj,
                         rule_id=division_rule.id,
                         config=config,
                     )

openwisp_controller/subnet_division/tasks.py

@@ -118,7 +118,7 @@ def _create_ipaddress_and_subnetdivision_index_objects(ips, indexes):
                 SubnetDivisionIndex(
                     keyword=f"{division_rule.label}_subnet{subnet.id}_ip{ip_id}",
                     subnet_id=subnet.id,
-                    ip_id=ip.id,
+                    ip=ip,
                     rule_id=division_rule.id,
                     config_id=index.config_id,
                 )

openwisp_controller/subnet_division/tests/test_models.py

@@ -1050,6 +1050,48 @@ def test_invalid_master_subnet(self):
             e.message_dict.get("master_subnet", []),
         )
 
+    def test_subnet_division_index_integrity(self):
+        rule = self._get_vpn_subdivision_rule()
+        self.config.templates.add(self.template)
+
+        # Verify initial indexes have non-NULL subnet_id and ip_id
+        # (if they are IP indexes)
+        indexes = rule.subnetdivisionindex_set.all()
+        self.assertTrue(indexes.exists())
+        initial_count = indexes.count()
+        for index in indexes:
+            self.assertIsNotNone(
+                index.subnet_id,
+                f"SubnetDivisionIndex {index.keyword} has NULL subnet_id",
+            )
+            if "_ip" in index.keyword:
+                self.assertIsNotNone(
+                    index.ip_id,
+                    f"SubnetDivisionIndex {index.keyword} has NULL ip_id",
+                )
+
+        # Update number of IPs to trigger tasks.provision_extra_ips
+        rule.number_of_ips = rule.number_of_ips + 2
+        rule.save()
+        rule.refresh_from_db()
+
+        # Verify count increased and all indexes, including new ones,
+        # have non-NULL subnet_id and ip_id
+        new_indexes = rule.subnetdivisionindex_set.all()
+        self.assertEqual(
+            new_indexes.count(), initial_count + (rule.number_of_subnets * 2)
+        )
+        for index in new_indexes:
+            self.assertIsNotNone(
+                index.subnet_id,
+                f"SubnetDivisionIndex {index.keyword} has NULL subnet_id after update",
+            )
+            if "_ip" in index.keyword:
+                self.assertIsNotNone(
+                    index.ip_id,
+                    f"SubnetDivisionIndex {index.keyword} has NULL ip_id after update",
+                )
+
 
 class TestOpenVPNSubnetDivisionRule(
     SubnetDivisionTestMixin,