support X | None = None with Gemini (#540)

Author: samuelcolvin

pydantic_ai_slim/pydantic_ai/models/gemini.py

@@ -701,7 +701,7 @@ def simplify(self) -> dict[str, Any]:
 
     def _simplify(self, schema: dict[str, Any], refs_stack: tuple[str, ...]) -> None:
         schema.pop('title', None)
-        schema.pop('default', None)
+        default = schema.pop('default', _utils.UNSET)
         if ref := schema.pop('$ref', None):
             # noinspection PyTypeChecker
             key = re.sub(r'^#/\$defs/', '', ref)
@@ -714,8 +714,14 @@ def _simplify(self, schema: dict[str, Any], refs_stack: tuple[str, ...]) -> None
             return
 
         if any_of := schema.get('anyOf'):
-            for schema in any_of:
-                self._simplify(schema, refs_stack)
+            for item_schema in any_of:
+                self._simplify(item_schema, refs_stack)
+            if len(any_of) == 2 and {'type': 'null'} in any_of and default is None:
+                for item_schema in any_of:
+                    if item_schema != {'type': 'null'}:
+                        schema.clear()
+                        schema.update(item_schema)
+                        return
 
         type_ = schema.get('type')
 

tests/models/test_gemini.py

@@ -261,14 +261,12 @@ class Locations(BaseModel):
                     parameters={
                         'properties': {
                             'op_location': {
-                                'anyOf': [
-                                    {
-                                        'properties': {'lat': {'type': 'number'}, 'lng': {'type': 'number'}},
-                                        'required': ['lat', 'lng'],
-                                        'type': 'object',
-                                    },
-                                    {'type': 'null'},
-                                ]
+                                'properties': {
+                                    'lat': {'type': 'number'},
+                                    'lng': {'type': 'number'},
+                                },
+                                'required': ['lat', 'lng'],
+                                'type': 'object',
                             }
                         },
                         'type': 'object',