Function apply_known_metadata

pydantic/_internal/_known_annotated_metadata.py:169–339

Apply `annotation` to `schema` if it is an annotation we know about (Gt, Le, etc.). Otherwise return `None`. This does not handle all known annotations. If / when it does, it can always return a CoreSchema and return the unmodified schema if the annotation should be ignored. Assume

(annotation: Any, schema: CoreSchema)

def apply_known_metadata(annotation: Any, schema: CoreSchema) -> CoreSchema | None:  # noqa: C901
    """Apply `annotation` to `schema` if it is an annotation we know about (Gt, Le, etc.).
    Otherwise return `None`.

    This does not handle all known annotations. If / when it does, it can always
    return a CoreSchema and return the unmodified schema if the annotation should be ignored.

    Assumes that GroupedMetadata has already been expanded via `expand_grouped_metadata`.

    Args:
        annotation: The annotation.
        schema: The schema.

    Returns:
        An updated schema with annotation if it is an annotation we know about, `None` otherwise.

    Raises:
        RuntimeError: If a constraint can't be applied to a specific schema type.
        ValueError: If an unknown constraint is encountered.
    """
    import annotated_types as at

    from ._validators import NUMERIC_VALIDATOR_LOOKUP, forbid_inf_nan_check

    schema = schema.copy()
    schema_update, other_metadata = collect_known_metadata([annotation])
    schema_type = schema['type']

    chain_schema_constraints: set[str] = {
        'pattern',
        'strip_whitespace',
        'to_lower',
        'to_upper',
        'coerce_numbers_to_str',
        'ascii_only',
    }
    chain_schema_steps: list[CoreSchema] = []

    for constraint, value in schema_update.items():
        if constraint not in CONSTRAINTS_TO_ALLOWED_SCHEMAS:
            raise ValueError(f'Unknown constraint {constraint}')
        allowed_schemas = CONSTRAINTS_TO_ALLOWED_SCHEMAS[constraint]

        # if it becomes necessary to handle more than one constraint
        # in this recursive case with function-after or function-wrap, we should refactor
        # this is a bit challenging because we sometimes want to apply constraints to the inner schema,
        # whereas other times we want to wrap the existing schema with a new one that enforces a new constraint.
        if schema_type in {'function-before', 'function-wrap', 'function-after'} and constraint == 'strict':
            schema['schema'] = apply_known_metadata(annotation, schema['schema'])  # type: ignore  # schema is function schema
            return schema

        # if we're allowed to apply constraint directly to the schema, like le to int, do that
        if schema_type in allowed_schemas:
            if constraint == 'union_mode' and schema_type == 'union':
                schema['mode'] = value  # type: ignore  # schema is UnionSchema
            else:
                schema[constraint] = value
            continue