Add to serializers to fix missing return types in config/flags schema (#10486)

* Add serializer fields to fix missing return types in schema

* Bump api version

* Fix api version bump

---------

Co-authored-by: Matthias Mair <code@mjmair.com>

src/backend/InvenTree/InvenTree/api_version.py

@@ -1,12 +1,15 @@
 """InvenTree API version information."""
 
 # InvenTree API version
-INVENTREE_API_VERSION = 399
+INVENTREE_API_VERSION = 400
 
 """Increment this API version number whenever there is a significant change to the API that any clients need to know about."""
 
 INVENTREE_API_TEXT = """
 
+v400 -> 2025-10-05 : https://github.com/inventree/InvenTree/pull/10486
+    - Adds return datatypes for admin/config and flags entpoints
+
 v399 -> 2025-10-05 : https://github.com/inventree/InvenTree/pull/10445
     - Refactors 'customer_detail' param in SalesOrder API endpoint
     - Refactors 'customer_detail' param in ReturnOrder API endpoint

src/backend/InvenTree/common/api.py

@@ -624,6 +624,9 @@ class FlagList(ListAPI):
     serializer_class = common.serializers.FlagSerializer
     permission_classes = [AllowAnyOrReadScope]
 
+    # Specifically disable pagination for this view
+    pagination_class = None
+
 
 class FlagDetail(RetrieveAPI):
     """Detail view for an individual feature flag."""

src/backend/InvenTree/common/serializers.py

@@ -340,6 +340,12 @@ class ConfigSerializer(serializers.Serializer):
     This is a read-only serializer.
     """
 
+    key = serializers.CharField(read_only=True)
+    env_var = serializers.CharField(read_only=True, allow_null=True)
+    config_key = serializers.CharField(read_only=True, allow_null=True)
+    source = serializers.CharField(read_only=True)
+    accessed = serializers.DateTimeField(read_only=True)
+
     def to_representation(self, instance):
         """Return the configuration data as a dictionary."""
         if not isinstance(instance, str):
@@ -406,6 +412,12 @@ class CustomStateSerializer(DataImportExportSerializerMixin, InvenTreeModelSeria
 class FlagSerializer(serializers.Serializer):
     """Serializer for feature flags."""
 
+    key = serializers.CharField(read_only=True)
+    state = serializers.CharField(read_only=True)
+    conditions = serializers.ListField(
+        child=serializers.DictField(), read_only=True, allow_null=True
+    )
+
     def to_representation(self, instance):
         """Return the configuration data as a dictionary."""
         request = self.context.get('request')