def _build_discriminated_union_meta()

in src/anthropic/_models.py [0:0]

• 43 lines of code
• 21 McCabe index (conditional complexity)

def _build_discriminated_union_meta(*, union: type, meta_annotations: tuple[Any, ...]) -> DiscriminatorDetails | None:
    if isinstance(union, CachedDiscriminatorType):
        return union.__discriminator__

    discriminator_field_name: str | None = None

    for annotation in meta_annotations:
        if isinstance(annotation, PropertyInfo) and annotation.discriminator is not None:
            discriminator_field_name = annotation.discriminator
            break

    if not discriminator_field_name:
        return None

    mapping: dict[str, type] = {}
    discriminator_alias: str | None = None

    for variant in get_args(union):
        variant = strip_annotated_type(variant)
        if is_basemodel_type(variant):
            if PYDANTIC_V2:
                field = _extract_field_schema_pv2(variant, discriminator_field_name)
                if not field:
                    continue

                # Note: if one variant defines an alias then they all should
                discriminator_alias = field.get("serialization_alias")

                field_schema = field["schema"]

                if field_schema["type"] == "literal":
                    for entry in cast("LiteralSchema", field_schema)["expected"]:
                        if isinstance(entry, str):
                            mapping[entry] = variant
            else:
                field_info = cast("dict[str, FieldInfo]", variant.__fields__).get(discriminator_field_name)  # pyright: ignore[reportDeprecated, reportUnnecessaryCast]
                if not field_info:
                    continue

                # Note: if one variant defines an alias then they all should
                discriminator_alias = field_info.alias

                if (annotation := getattr(field_info, "annotation", None)) and is_literal_type(annotation):
                    for entry in get_args(annotation):
                        if isinstance(entry, str):
                            mapping[entry] = variant

    if not mapping:
        return None

    details = DiscriminatorDetails(
        mapping=mapping,
        discriminator_field=discriminator_field_name,
        discriminator_alias=discriminator_alias,
    )
    cast(CachedDiscriminatorType, union).__discriminator__ = details
    return details