[Fix] Merging with wrong format now raises Validation error #351

netjsonconfig/utils.py

@@ -3,6 +3,12 @@
 from copy import deepcopy
 
 
+class ValidationError(Exception):
+    """exception for validation errors during config merge"""
+
+    pass
+
+
 def merge_config(template, config, list_identifiers=None):
     """
     Merges ``config`` on top of ``template``.
@@ -23,10 +29,24 @@ def merge_config(template, config, list_identifiers=None):
     result = deepcopy(template)
     for key, value in config.items():
         if isinstance(value, dict):
-            node = result.get(key, OrderedDict())
-            result[key] = merge_config(node, value)
-        elif isinstance(value, list) and isinstance(result.get(key), list):
-            result[key] = merge_list(result[key], value, list_identifiers)
+            if isinstance(result.get(key), dict) or key not in result:
+                node = result.get(key, OrderedDict())
+                result[key] = merge_config(node, value)
+            else:
+                raise ValidationError(
+                    f"Cannot merge dict into non-dict for key '{key}': "
+                    f"{type(result.get(key)).__name__} vs dict"
+                )
+        elif isinstance(value, list):
+            if isinstance(result.get(key), list):
+                result[key] = merge_list(result[key], value, list_identifiers)
+            elif key in result:
+                raise ValidationError(
+                    f"Cannot merge list into non-list for key '{key}': "
+                    f"{type(result.get(key)).__name__} vs list"
+                )
+            else:
+                result[key] = value
         else:
             result[key] = value
     return result

tests/openwrt/test_default.py

@@ -3,7 +3,7 @@
 from openwisp_utils.tests import capture_stdout
 
 from netjsonconfig import OpenWrt
-from netjsonconfig.utils import _TabsMixin
+from netjsonconfig.utils import ValidationError, _TabsMixin
 
 
 class TestDefault(unittest.TestCase, _TabsMixin):
@@ -251,3 +251,30 @@ def test_render_invalid_uci_name(self):
 """
         )
         self.assertEqual(o.render(), expected)
+
+    def test_merge_invalid_format(self):
+        invalid = {
+            "dhcp": {
+                "lan": {
+                    "interface": "lan",
+                    "start": 100,
+                    "limit": 150,
+                    "leasetime": "12h",
+                }
+            }
+        }
+        valid = {
+            "dhcp": [
+                {
+                    "dhcpv6": "disabled",
+                    "ignore": True,
+                    "ra": "disabled",
+                    "config_value": "lan",
+                    "config_name": "dhcp",
+                }
+            ]
+        }
+        with self.assertRaises(ValidationError) as context:
+            OpenWrt({}, templates=[valid, invalid]).validate()
+
+        self.assertIn("Cannot merge dict into non-dict", str(context.exception))