✅ [#4699] Validate postcode and houseNumber

When the addressNL component is optional, the postcode and houseNumber fields should also be considered optional. But, if either postcode or houseNumber is provided, both fields become required

src/openforms/formio/components/custom.py

@@ -468,11 +468,23 @@ def validate(self, attrs):
 
         city = attrs.get("city", "")
         street_name = attrs.get("streetName", "")
+        postcode = attrs.get("postcode", "")
+        number = attrs.get("houseNumber", "")
+
+        if postcode and not number:
+            raise serializers.ValidationError(
+                {"houseNumber": _('This field is required if "postcode" is provided')},
+                code="required",
+            )
+
+        if not postcode and number:
+            raise serializers.ValidationError(
+                {"postcode": _('This field is required if "house number" is provided')},
+                code="required",
+            )
 
         if self.derive_address:
             existing_hmac = attrs.get("secretStreetCity", "")
-            postcode = attrs.get("postcode", "")
-            number = attrs.get("houseNumber", "")
 
             computed_hmac = salt_location_message(
                 {

src/openforms/formio/tests/validation/test_addressnl.py

@@ -106,29 +106,6 @@ def test_addressNL_field_regex_pattern_success(self):
 
         self.assertTrue(is_valid)
 
-    def test_missing_keys(self):
-        component: AddressNLComponent = {
-            "key": "addressNl",
-            "type": "addressNL",
-            "label": "AddressNL missing keys",
-            "deriveAddress": False,
-        }
-
-        invalid_values = {
-            "addressNl": {
-                "houseLetter": "A",
-            }
-        }
-
-        is_valid, errors = validate_formio_data(component, invalid_values)
-
-        postcode_error = extract_error(errors["addressNl"], "postcode")
-        house_number_error = extract_error(errors["addressNl"], "houseNumber")
-
-        self.assertFalse(is_valid)
-        self.assertEqual(postcode_error.code, "required")
-        self.assertEqual(house_number_error.code, "required")
-
     def test_plugin_validator(self):
         with replace_validators_registry() as register:
             register("postcode_validator")(PostcodeValidator)
@@ -376,3 +353,57 @@ def test_addressNL_custom_postcode_and_city_validation_success(self):
         is_valid, _ = validate_formio_data(component, data)
 
         self.assertTrue(is_valid)
+
+    def test_addressNL_when_non_required_postcode_is_required_if_houseNumber_is_provided(
+        self,
+    ):
+        component: AddressNLComponent = {
+            "key": "addressNl",
+            "type": "addressNL",
+            "label": "AddressNL",
+            "deriveAddress": False,
+        }
+
+        data = {
+            "addressNl": {
+                "postcode": "",
+                "houseNumber": "117",
+                "houseLetter": "",
+                "houseNumberAddition": "",
+                "city": "Amsterdam",
+                "streetName": "",
+            }
+        }
+
+        is_valid, errors = validate_formio_data(component, data)
+        postcode_error = extract_error(errors["addressNl"], "postcode")
+
+        self.assertFalse(is_valid)
+        self.assertEqual(postcode_error.code, "required")
+
+    def test_addressNL_when_non_required_houseNumber_is_required_if_postcode_is_provided(
+        self,
+    ):
+        component: AddressNLComponent = {
+            "key": "addressNl",
+            "type": "addressNL",
+            "label": "AddressNL",
+            "deriveAddress": False,
+        }
+
+        data = {
+            "addressNl": {
+                "postcode": "1234 AB",
+                "houseNumber": "",
+                "houseLetter": "",
+                "houseNumberAddition": "",
+                "city": "Amsterdam",
+                "streetName": "",
+            }
+        }
+
+        is_valid, errors = validate_formio_data(component, data)
+        house_number_error = extract_error(errors["addressNl"], "houseNumber")
+
+        self.assertFalse(is_valid)
+        self.assertEqual(house_number_error.code, "required")