Fix schema config for extra fields

Author: muralibasani

src/karapace/api/routers/requests.py

@@ -22,7 +22,7 @@ class SchemaRequest(BaseModel):
     references: list[SchemaReference] | None = None
     metadata: Any | None = None
     ruleSet: Any | None = None
-    model_config = ConfigDict(extra="forbid")
+    model_config = ConfigDict(extra="ignore")
 
     @field_validator("schema_str")
     @classmethod

tests/integration/test_schema.py

@@ -2168,7 +2168,7 @@ async def test_schema_body_validation(registry_async_client: Client) -> None:
     subject = create_subject_name_factory("test_schema_body_validation")()
     post_functions = {registry_async_client.post_subjects, registry_async_client.post_subjects_versions}
     for function in post_functions:
-        # Wrong field name
+        # Wrong field name (required field "schema" is still missing)
         res = await function(subject=subject, json={"invalid_field": "invalid_value"})
         assert res.status_code == 422
         assert res.json()["error_code"] == 422
@@ -2179,25 +2179,10 @@ async def test_schema_body_validation(registry_async_client: Client) -> None:
                 "msg": "Field required",
                 "input": {"invalid_field": "invalid_value"},
             },
-            {
-                "type": "extra_forbidden",
-                "loc": ["body", "invalid_field"],
-                "msg": "Extra inputs are not permitted",
-                "input": "invalid_value",
-            },
         ]
-        # Additional field
+        # Additional field (extra fields are ignored to match v4 behavior)
         res = await function(subject=subject, json={"schema": '{"type": "string"}', "invalid_field": "invalid_value"})
-        assert res.status_code == 422
-        assert res.json()["error_code"] == 422
-        assert res.json()["message"] == [
-            {
-                "type": "extra_forbidden",
-                "loc": ["body", "invalid_field"],
-                "msg": "Extra inputs are not permitted",
-                "input": "invalid_value",
-            },
-        ]
+        assert res.ok
         # Invalid body type
         res = await function(subject=subject, json="invalid")
         assert res.status_code == 422

tests/unit/api/test_requests.py

@@ -0,0 +1,63 @@
+"""
+karapace - unit tests for request models
+
+Copyright (c) 2025 Aiven Ltd
+See LICENSE for details
+"""
+
+import pytest
+from pydantic import ValidationError
+
+from karapace.api.routers.requests import SchemaRequest
+
+
+class TestSchemaRequestExtraFields:
+    """Extra fields must be silently ignored to match v4 behavior.
+
+    v4 parsed the request body as a plain dict and only read the keys it
+    needed.  The 5.x Pydantic model must not reject unknown keys so that
+    existing clients that send extra properties (e.g. ``compatibility``)
+    continue to work after upgrading.
+    """
+
+    def test_extra_fields_are_ignored(self) -> None:
+        req = SchemaRequest.model_validate(
+            {
+                "schema": '{"type": "string"}',
+                "compatibility": "BACKWARD",
+            }
+        )
+        assert req.schema_str == '{"type": "string"}'
+        assert not hasattr(req, "compatibility")
+
+    def test_multiple_extra_fields_are_ignored(self) -> None:
+        req = SchemaRequest.model_validate(
+            {
+                "schema": '{"type": "string"}',
+                "compatibility": "BACKWARD",
+                "unknown_prop": 123,
+                "another": True,
+            }
+        )
+        assert req.schema_str == '{"type": "string"}'
+
+    def test_required_field_still_validated(self) -> None:
+        with pytest.raises(ValidationError) as exc_info:
+            SchemaRequest.model_validate(
+                {
+                    "compatibility": "BACKWARD",
+                }
+            )
+        errors = exc_info.value.errors()
+        assert any(e["type"] == "missing" for e in errors)
+
+    def test_valid_request_with_all_fields(self) -> None:
+        req = SchemaRequest.model_validate(
+            {
+                "schema": '{"type": "string"}',
+                "schemaType": "AVRO",
+                "references": None,
+            }
+        )
+        assert req.schema_str == '{"type": "string"}'
+        assert req.schema_type.value == "AVRO"