Inline $ref and $defs in JSON schema in with_structured_output (#76)

Added resolve_schema_refs to OCIUtils to inline $ref and $defs in JSON schema, as OCI Generative AI does not support these features. Updated ChatOCIGenAI to use this utility before passing schemas to the provider. Added a unit test to verify correct handling of nested $ref in structured output schemas.

Author: paxiaatucsdedu

libs/oci/langchain_oci/chat_models/oci_generative_ai.py

@@ -118,6 +118,31 @@ def convert_oci_tool_call_to_langchain(tool_call: Any) -> ToolCall:
             id=tool_call.id if "id" in tool_call.attribute_map else uuid.uuid4().hex[:],
         )
 
+    @staticmethod
+    def resolve_schema_refs(schema: Dict[str, Any]) -> Dict[str, Any]:
+        """
+        OCI Generative AI doesn't support $ref and $defs, so we inline all references.
+        """
+        defs = schema.get("$defs", {})  # OCI Generative AI doesn't support $defs
+
+        def resolve(obj: Any) -> Any:
+            if isinstance(obj, dict):
+                if "$ref" in obj:
+                    ref = obj["$ref"]
+                    if ref.startswith("#/$defs/"):
+                        key = ref.split("/")[-1]
+                        return resolve(defs.get(key, obj))
+                    return obj  # Cannot resolve $ref, return unchanged
+                return {k: resolve(v) for k, v in obj.items()}
+            elif isinstance(obj, list):
+                return [resolve(item) for item in obj]
+            return obj
+
+        resolved = resolve(schema)
+        if isinstance(resolved, dict):
+            resolved.pop("$defs", None)
+        return resolved
+
 
 class Provider(ABC):
     """Abstract base class for OCI Generative AI providers."""
@@ -1371,6 +1396,9 @@ def with_structured_output(
                 else schema  # type: ignore[assignment]
             )
 
+            # Resolve $ref references as OCI doesn't support $ref and $defs
+            json_schema_dict = OCIUtils.resolve_schema_refs(json_schema_dict)
+
             response_json_schema = self._provider.oci_response_json_schema(
                 name=json_schema_dict.get("title", "response"),
                 description=json_schema_dict.get("description", ""),

libs/oci/tests/unit_tests/chat_models/test_response_format.py

@@ -111,7 +111,6 @@ def test_with_structured_output_json_schema():
     oci_gen_ai_client = MagicMock()
     llm = ChatOCIGenAI(model_id="meta.llama-3.3-70b-instruct", client=oci_gen_ai_client)
 
-    # This should not raise TypeError anymore
     from pydantic import BaseModel
 
     class TestSchema(BaseModel):
@@ -126,6 +125,36 @@ class TestSchema(BaseModel):
     assert structured_llm is not None
 
 
+@pytest.mark.requires("oci")
+def test_with_structured_output_json_schema_nested_refs():
+    """Test with_structured_output with json_schema method and nested refs."""
+    oci_gen_ai_client = MagicMock()
+    llm = ChatOCIGenAI(model_id="meta.llama-3.3-70b-instruct", client=oci_gen_ai_client)
+
+    from enum import Enum
+    from typing import List
+
+    from pydantic import BaseModel
+
+    class Color(Enum):
+        RED = "RED"
+        BLUE = "BLUE"
+        GREEN = "GREEN"
+
+    class Item(BaseModel):
+        name: str
+        color: Color  # Creates $ref to Color
+
+    class Response(BaseModel):
+        message: str
+        items: List[Item]  # Array with $ref inside
+
+    structured_llm = llm.with_structured_output(schema=Response, method="json_schema")
+
+    # The structured LLM should be created without errors
+    assert structured_llm is not None
+
+
 @pytest.mark.requires("oci")
 def test_response_format_json_schema_object():
     """Test response_format with JsonSchemaResponseFormat object."""