feat: provide a field serializer in DandiBaseModel to handle types in anys

This serializer allows serialization
of model instances containing field
values that are of types from the
anys pacakge,
https://pypi.org/project/anys/. This
is needed for tests that uses the
anys types, such as the ones in dandi-cli.
This solution was initially proposed
at dandi/dandi-cli#1716 (comment)

Author: candleindark

dandischema/models.py

@@ -26,9 +26,11 @@
     EmailStr,
     Field,
     GetJsonSchemaHandler,
+    SerializerFunctionWrapHandler,
     StringConstraints,
     TypeAdapter,
     ValidationInfo,
+    field_serializer,
     field_validator,
     model_validator,
 )
@@ -508,6 +510,19 @@ def json_dict(self) -> dict:
         )
         return self.model_dump(mode="json", exclude_none=True)
 
+    @field_serializer("*", mode="wrap")
+    def ignore_any_types(
+        self, value: Any, handler: SerializerFunctionWrapHandler
+    ) -> Any:
+        try:
+            from anys import AnyBase
+        except ImportError:
+            pass
+        else:
+            if isinstance(value, AnyBase):
+                return value
+        return handler(value)
+
     @field_validator("schemaKey")
     @classmethod
     def ensure_schemakey(cls, val: str) -> str: