fix(utils): default value for defaults as objects

CHANGELOG.md

@@ -21,6 +21,7 @@ should change the heading of the (upcoming) version to include a major version b
 ## @rjsf/utils
 
 - Fixed issue where oneOf radio button could not be modified when defaults were set, fixing [#4634](https://github.com/rjsf-team/react-jsonschema-form/issues/4634)
+- Fix default value for object properties such as enums that are rendered in select, radio inputs, etc.
 
 # 6.0.0-beta.10
 

packages/utils/src/mergeDefaultsWithFormData.ts

@@ -67,8 +67,22 @@ export default function mergeDefaultsWithFormData<T = any>(
       const keyValue = get(formData, key);
       const keyExistsInDefaults = isObject(defaults) && key in (defaults as GenericObjectType);
       const keyExistsInFormData = key in (formData as GenericObjectType);
+      const keyDefault = get(defaults, key) ?? {};
+      const defaultValueIsNestedObject = keyExistsInDefaults && Object.entries(keyDefault).some(([, v]) => isObject(v));
+
+      const keyDefaultIsObject = keyExistsInDefaults && isObject(get(defaults, key));
+      const keyHasFormDataObject = keyExistsInFormData && isObject(keyValue);
+
+      if (keyDefaultIsObject && keyHasFormDataObject && !defaultValueIsNestedObject) {
+        acc[key as keyof T] = {
+          ...get(defaults, key),
+          ...keyValue,
+        };
+        return acc;
+      }
+
       acc[key as keyof T] = mergeDefaultsWithFormData<T>(
-        defaults ? get(defaults, key) : {},
+        get(defaults, key) ?? {},
         keyValue,
         mergeExtraArrayDefaults,
         defaultSupercedesUndefined,

packages/utils/src/schema/getDefaultFormState.ts

@@ -728,6 +728,13 @@ export default function getDefaultFormState<
     shouldMergeDefaultsIntoFormData: true,
   });
 
+  if (schema.type !== 'object' && isObject(schema.default)) {
+    return {
+      ...defaults,
+      ...formData,
+    } as T;
+  }
+
   // If the formData is an object or an array, add additional properties from formData and override formData with
   // defaults since the defaults are already merged with formData.
   if (isObject(formData) || Array.isArray(formData)) {

packages/utils/test/schema/getDefaultFormStateTest.ts

@@ -1342,6 +1342,28 @@ export default function getDefaultFormStateTest(testValidator: TestValidatorType
         });
       });
 
+      describe('an object with a valid formData and enum property with default value', () => {
+        test('getDefaultFormState', () => {
+          const schema: RJSFSchema = {
+            type: 'object',
+            properties: {
+              test: {
+                type: 'string',
+                enum: [
+                  { label: 'a', value: 'a' },
+                  { label: 'b', value: 'b' },
+                ],
+                default: { label: 'a', value: 'a' },
+              },
+            },
+          };
+
+          expect(getDefaultFormState(testValidator, schema, { test: { label: 'b', value: 'b' } })).toEqual({
+            test: { label: 'b', value: 'b' },
+          });
+        });
+      });
+
       describe('oneOf with const values', () => {
         const schema: RJSFSchema = {
           type: 'object',
@@ -1970,6 +1992,22 @@ export default function getDefaultFormStateTest(testValidator: TestValidatorType
 
         expect(ensureFormDataMatchingSchema(testValidator, schema, schema, 'a')).toEqual('a');
       });
+
+      it('Test schema with valid formData with an enum and its default value', () => {
+        schema = {
+          type: 'string',
+          enum: [
+            { label: 'a', value: 'a' },
+            { label: 'b', value: 'b' },
+          ],
+          default: { label: 'a', value: 'a' },
+        };
+
+        expect(getDefaultFormState(testValidator, schema, { label: 'b', value: 'b' })).toEqual({
+          label: 'b',
+          value: 'b',
+        });
+      });
     });
     describe('AJV $data reference in const property in schema should not be treated as default/const value', () => {
       let schema: RJSFSchema;