[#4774] Added normalizer method to the the Textfield component

Backport-of: #4775

src/openforms/formio/components/vanilla.py

@@ -91,6 +91,12 @@ class Default(BasePlugin):
 class TextField(BasePlugin[TextFieldComponent]):
     formatter = TextFieldFormatter
 
+    @staticmethod
+    def normalizer(component: Component, value: str) -> str:
+        if isinstance(value, (int, float)):
+            return str(value)
+        return value
+
     def build_serializer_field(
         self, component: TextFieldComponent
     ) -> serializers.CharField | serializers.ListField:

src/openforms/formio/tests/test_normalization.py

@@ -1,4 +1,4 @@
-from django.test import SimpleTestCase
+from django.test import SimpleTestCase, tag
 
 from ..service import normalize_value_for_component
 
@@ -63,3 +63,13 @@ def test_normalize_unknown_component_type(self):
         result = normalize_value_for_component(component, "foo.bar-baz")
 
         self.assertEqual(result, "foo.bar-baz")  # unmodified
+
+    @tag("gh-4774")
+    def test_textfield_normalization_non_str(self):
+        component = {"type": "textfield"}
+
+        int_result = normalize_value_for_component(component, 9)
+        float_result = normalize_value_for_component(component, 9.9)
+
+        self.assertEqual(int_result, "9")
+        self.assertEqual(float_result, "9.9")