Fix handling of optional fields such as user_handle.

UserHandle is tagged as Optional[bytes] so field.annotation == bytes doesn't match - add explicit match for user_handle.

The conversion from base64 should only be done if input was json - there was a comment to this effect that that didn't work when using parse_raw - but
recent releases, using Pydantic 2.0 no longer use those deprecated methods.

.gitignore

@@ -73,6 +73,9 @@ target/
 # Jupyter Notebook
 .ipynb_checkpoints
 
+# PyCharm
+.idea
+
 # pyenv
 .python-version
 

webauthn/helpers/structs.py

@@ -85,13 +85,11 @@ def _pydantic_v2_validate_bytes_fields(
  """
  field = cls.model_fields[info.field_name] # type: ignore[attr-defined]
 
- if field.annotation != bytes:
+ # UserHandle is defined as Optional[bytes]
+ if field.annotation != bytes and info.field_name != 'user_handle':
  return v
 
- if isinstance(v, str):
- # NOTE:
- # Ideally we should only do this when info.mode == "json", but
- # that does not work when using the deprecated parse_raw method
+ if isinstance(v, str) and info.mode == "json":
  return base64url_to_bytes(v)
 
  return _to_bytes(v)