8864 Add support for anyOf union type while handling null fields

.gitignore

@@ -82,4 +82,4 @@ tests/llm_translation/test_vertex_key.json
 litellm/proxy/migrations/0_init/migration.sql
 litellm/proxy/db/migrations/0_init/migration.sql
 litellm/proxy/db/migrations/*
-litellm/proxy/migrations/*
+litellm/proxy/migrations/*config.yaml

litellm/llms/vertex_ai/common_utils.py

@@ -160,7 +160,7 @@ def _build_vertex_schema(parameters: dict):
     #     * https://github.com/pydantic/pydantic/issues/1270
     #     * https://stackoverflow.com/a/58841311
     #     * https://github.com/pydantic/pydantic/discussions/4872
-    convert_to_nullable(parameters)
+    convert_anyof_null_to_nullable(parameters)
     add_object_type(parameters)
     # Postprocessing
     # 4. Suppress unnecessary title generation:
@@ -211,34 +211,39 @@ def unpack_defs(schema, defs):
                 continue
 
 
-def convert_to_nullable(schema):
-    anyof = schema.pop("anyOf", None)
+def convert_anyof_null_to_nullable(schema):
+    """ Converts null objects within anyOf by removing them and adding nullable to all remaining objects """
+    anyof = schema.get("anyOf", None)
     if anyof is not None:
-        if len(anyof) != 2:
+        contains_null = False
+        for atype in anyof:
+            if atype == {"type": "null"}:
+                # remove null type
+                anyof.remove(atype)
+                contains_null = True
+        
+        if len(anyof) == 0:
+            # Edge case: response schema with only null type present is invalid in Vertex AI
             raise ValueError(
-                "Invalid input: Type Unions are not supported, except for `Optional` types. "
-                "Please provide an `Optional` type or a non-Union type."
+                "Invalid input: AnyOf schema with only null type is not supported. "
+                "Please provide a non-null type."
             )
-        a, b = anyof
-        if a == {"type": "null"}:
-            schema.update(b)
-        elif b == {"type": "null"}:
-            schema.update(a)
-        else:
-            raise ValueError(
-                "Invalid input: Type Unions are not supported, except for `Optional` types. "
-                "Please provide an `Optional` type or a non-Union type."
-            )
-        schema["nullable"] = True
+
+            
+        if contains_null:
+            # set all types to nullable following guidance found here: https://cloud.google.com/vertex-ai/generative-ai/docs/samples/generativeaionvertexai-gemini-controlled-generation-response-schema-3#generativeaionvertexai_gemini_controlled_generation_response_schema_3-python
+            for atype in anyof:
+                atype["nullable"] = True
+            
 
     properties = schema.get("properties", None)
     if properties is not None:
         for name, value in properties.items():
-            convert_to_nullable(value)
+            convert_anyof_null_to_nullable(value)
 
     items = schema.get("items", None)
     if items is not None:
-        convert_to_nullable(items)
+        convert_anyof_null_to_nullable(items)
 
 
 def add_object_type(schema):

tests/litellm/llms/vertex_ai/test_vertex_ai_common_utils.py

@@ -12,6 +12,7 @@ import litellm
 from litellm.llms.vertex_ai.common_utils import (
     get_vertex_location_from_url,
     get_vertex_project_id_from_url,
+    convert_anyof_null_to_nullable
 )
 
 
@@ -41,3 +42,72 @@ async def test_get_vertex_location_from_url():
     url = "https://invalid-url.com"
     location = get_vertex_location_from_url(url)
     assert location is None
+
+def test_basic_anyof_conversion():
+    """Test basic conversion of anyOf with 'null'."""
+    schema = {
+        "type": "object",
+        "properties": {
+            "example": {
+                "anyOf": [
+                    {"type": "string"},
+                    {"type": "null"}
+                ]
+            }
+        }
+    }
+
+    convert_anyof_null_to_nullable(schema)
+
+    expected = {
+        "type": "object",
+        "properties": {
+            "example": {
+                "anyOf": [
+                    {"type": "string", "nullable": True}
+                ]
+            }
+        }
+    }
+    assert schema == expected
+
+
+def test_nested_anyof_conversion():
+    """Test nested conversion with 'anyOf' inside properties."""
+    schema = {
+        "type": "object",
+        "properties": {
+            "outer": {
+                "type": "object",
+                "properties": {
+                    "inner": {
+                        "anyOf": [
+                            {"type": "array", "items": {"type": "string"}},
+                            {"type": "string"},
+                            {"type": "null"}
+                        ]
+                    }
+                }
+            }
+        }
+    }
+
+    convert_anyof_null_to_nullable(schema)
+
+    expected = {
+        "type": "object",
+        "properties": {
+            "outer": {
+                "type": "object",
+                "properties": {
+                    "inner": {
+                        "anyOf": [
+                            {"type": "array", "items": {"type": "string"}, "nullable": True},
+                            {"type": "string", "nullable": True}
+                        ]
+                    }
+                }
+            }
+        }
+    }
+    assert schema == expected