api: fix case of boolean user's attributs (fixes #26113)

As NullBooleanField does not support the allow_null init attribute, we
must special case it and remember to never use BooleanField.

src/authentic2/api_views.py

@@ -339,7 +339,11 @@ class BaseUserSerializer(serializers.ModelSerializer):
                 })
                 if not at.required:
                     # setting an attribute to null will delete it
-                    kwargs['allow_null'] = True
+                    # NullBooleanField and BooleanField does not support allow_null
+                    if field_class is serializers.BooleanField:
+                        field_class = serializers.NullBooleanField
+                    elif field_class is not serializers.NullBooleanField:
+                        kwargs['allow_null'] = True
                     # if not stated otherwise by the definition of the kind, string alike fields
                     # accept blank values when not required
                     if (issubclass(field_class, serializers.CharField) and 'allow_blank' not in

tests/test_api.py

@@ -151,6 +151,16 @@ def test_api_users_boolean_attribute(app, superuser):
     assert resp.json['boolean'] is True
 
 
+def test_api_users_boolean_attribute_optional(app, superuser):
+    from authentic2.models import Attribute, AttributeValue
+    at = Attribute.objects.create(
+        kind='boolean', name='boolean', label='boolean', required=False)
+    superuser.attributes.boolean = True
+    app.authorization = ('Basic', (superuser.username, superuser.username))
+    resp = app.get('/api/users/%s/' % superuser.uuid)
+    assert resp.json['boolean'] is True
+
+
 def test_api_users_list_by_authorized_service(app, superuser):
     from authentic2.models import Service