B: Fix cyclic block hierarchy

rsconcept/backend/apps/oss/serializers/data_access.py

@@ -123,7 +123,7 @@ class UpdateBlockSerializer(StrictSerializer):
                 raise serializers.ValidationError({
                     'parent': msg.parentNotInOSS()
                 })
-            if parent == attrs['target']:
+            if attrs['target'].pk in _collect_ancestors(parent):
                 raise serializers.ValidationError({
                     'parent': msg.blockCyclicHierarchy()
                 })

rsconcept/backend/apps/oss/tests/s_views/t_blocks.py

@@ -266,3 +266,36 @@ class TestOssBlocks(EndpointTester):
 
         data['layout'] = self.layout_data
         self.executeOK(data=data)
+
+
+    @decl_endpoint('/api/oss/{item}/update-block', method='patch')
+    def test_update_block_cyclic_parent(self):
+        self.populateData()
+        # block1 -> block2
+        # Try to set block1's parent to block2 (should fail, direct cycle)
+        data = {
+            'target': self.block1.pk,
+            'item_data': {
+                'title': self.block1.title,
+                'description': self.block1.description,
+                'parent': self.block2.pk
+            },
+        }
+        self.executeBadData(data=data, item=self.owned_id)
+
+        # Create a deeper hierarchy: block1 -> block2 -> block3
+        self.block3 = self.owned.create_block(title='3', parent=self.block2)
+        # Try to set block1's parent to block3 (should fail, indirect cycle)
+        data['item_data']['parent'] = self.block3.pk
+        self.executeBadData(data=data, item=self.owned_id)
+
+        # Setting block2's parent to block1 (valid, as block1 is not a descendant)
+        data = {
+            'target': self.block2.pk,
+            'item_data': {
+                'title': self.block2.title,
+                'description': self.block2.description,
+                'parent': self.block1.pk
+            },
+        }
+        self.executeOK(data=data, item=self.owned_id)

rsconcept/frontend/src/features/oss/dialogs/dlg-edit-block.tsx

@@ -66,14 +66,18 @@ export function DlgEditBlock() {
       <Controller
         name='item_data.parent'
         control={control}
-        render={({ field }) => (
+        render={({ field }) => {
-          <SelectParent
+          const descendantNodeIDs = manager.oss.hierarchy.expandAllOutputs([target.nodeID]);
-            items={manager.oss.blocks.filter(block => block.id !== target.id)}
+          descendantNodeIDs.push(target.nodeID);
-            value={field.value ? manager.oss.blockByID.get(field.value) ?? null : null}
+          return (
-            placeholder='Родительский блок'
+            <SelectParent
-            onChange={value => field.onChange(value ? value.id : null)}
+              items={manager.oss.blocks.filter(block => !descendantNodeIDs.includes(block.nodeID))}
-          />
+              value={field.value ? manager.oss.blockByID.get(field.value) ?? null : null}
-        )}
+              placeholder='Родительский блок'
+              onChange={value => field.onChange(value ? value.id : null)}
+            />
+          );
+        }}
       />
 
       <TextArea