From e0bacf113ac2e4631d0a5db2e821b1032fe4e40d Mon Sep 17 00:00:00 2001
From: Viicos <65306057+Viicos@users.noreply.github.com>
Date: Thu, 4 Apr 2024 09:31:40 +0200
Subject: [PATCH 1/2] [#4096] Fix validation of hidden radio component

---
 src/openforms/formio/serializers.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/openforms/formio/serializers.py b/src/openforms/formio/serializers.py
index dea899300c..3345465352 100644
--- a/src/openforms/formio/serializers.py
+++ b/src/openforms/formio/serializers.py
@@ -87,6 +87,9 @@ def _remove_validations_from_field(self, field: serializers.Field) -> None:
                 field.min_length = None
                 field.max_length = None
 
+            case serializers.ChoiceField():
+                field.allow_blank = True
+
     def _get_required(self) -> bool:
         return any(field.required for field in self.fields.values())
 

From 44d161e9470871afe41f8cf03b7426ee7bb12f61 Mon Sep 17 00:00:00 2001
From: Viicos <65306057+Viicos@users.noreply.github.com>
Date: Thu, 4 Apr 2024 09:31:56 +0200
Subject: [PATCH 2/2] [#4096] Add regression test for hidden radio component

---
 .../formio/tests/validation/test_radio.py     | 31 +++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/src/openforms/formio/tests/validation/test_radio.py b/src/openforms/formio/tests/validation/test_radio.py
index e69de29bb2..d21d62e9b1 100644
--- a/src/openforms/formio/tests/validation/test_radio.py
+++ b/src/openforms/formio/tests/validation/test_radio.py
@@ -0,0 +1,31 @@
+from django.test import SimpleTestCase, tag
+
+from openforms.typing import JSONObject
+
+from ...typing import RadioComponent
+from .helpers import validate_formio_data
+
+
+class RadioValidationTests(SimpleTestCase):
+
+    @tag("gh-4096")
+    def test_radio_hidden_required(self):
+        component: RadioComponent = {
+            "type": "radio",
+            "key": "radio",
+            "label": "Radio",
+            "values": [
+                {"label": "Opt1", "value": "opt1"},
+                {"label": "Opt2", "value": "opt2"},
+            ],
+            "hidden": True,
+            "validate": {
+                "required": True,
+            },
+        }
+
+        # This happens when `clearOnHide` is `False`:
+        data: JSONObject = {"radio": ""}
+
+        is_valid, _ = validate_formio_data(component, data)
+        self.assertTrue(is_valid)