Function _extract_field_infos

python/pyfory/struct.py:187–317

Extract FieldInfo list from a dataclass. This handles: - Extracting field metadata from pyfory.field() annotations - Filtering out ignored fields - Computing effective nullable based on Optional[T] - Computing runtime ref tracking based on global config - Inheritance: p

(
    fory,
    clz: type,
    type_hints: dict,
)

def _extract_field_infos(
    fory,
    clz: type,
    type_hints: dict,
) -> tuple[list[FieldInfo], dict[str, ForyFieldMeta]]:
    """
    Extract FieldInfo list from a dataclass.

    This handles:
    - Extracting field metadata from pyfory.field() annotations
    - Filtering out ignored fields
    - Computing effective nullable based on Optional[T]
    - Computing runtime ref tracking based on global config
    - Inheritance: parent fields first, subclass fields override parent fields

    Returns:
        Tuple of (field_infos, field_metas) where field_metas maps field name to ForyFieldMeta
    """
    if not dataclasses.is_dataclass(clz):
        # Non-dataclass registration uses the runtime type inspection path.
        return [], {}

    # Collect fields from class hierarchy (parent first, child last)
    # Child fields override parent fields with same name
    all_fields: Dict[str, dataclasses.Field] = {}
    for klass in clz.__mro__[::-1]:  # Reverse MRO: base classes first
        if dataclasses.is_dataclass(klass) and klass is not clz:
            for f in dataclasses.fields(klass):
                all_fields[f.name] = f
    # Add current class fields (override parent)
    for f in dataclasses.fields(clz):
        all_fields[f.name] = f

    # Extract field metas and filter ignored fields
    field_metas: Dict[str, ForyFieldMeta] = {}
    active_fields: List[tuple] = []

    # Check if fory has field_nullable global setting
    global_field_nullable = getattr(fory, "field_nullable", False)

    for field_name, dc_field in all_fields.items():
        meta = extract_field_meta(dc_field)
        if meta is None:
            # Field without pyfory.field() - use defaults
            # Auto-detect Optional[T] for nullable, also respect global field_nullable
            field_type = type_hints.get(field_name, typing.Any)
            meta = _default_field_meta(field_type, global_field_nullable, getattr(fory, "xlang", False))

        field_metas[field_name] = meta

        if not meta.ignore:
            active_fields.append((field_name, dc_field))

    # Validate field metas
    validate_field_metas(clz, field_metas, type_hints)

    # Build FieldInfo list
    field_infos: List[FieldInfo] = []