Class PositionalArgumentsFormatter

src/structlog/stdlib.py:767–808

Apply stdlib-like string formatting to the ``event`` key. If the ``positional_args`` key in the event dict is set, it must contain a tuple that is used for formatting (using the ``%s`` string formatting operator) of the value from the ``event`` key. This works in the same way

class PositionalArgumentsFormatter:
    """
    Apply stdlib-like string formatting to the ``event`` key.

    If the ``positional_args`` key in the event dict is set, it must
    contain a tuple that is used for formatting (using the ``%s`` string
    formatting operator) of the value from the ``event`` key.  This works
    in the same way as the stdlib handles arguments to the various log
    methods: if the tuple contains only a single `dict` argument it is
    used for keyword placeholders in the ``event`` string, otherwise it
    will be used for positional placeholders.

    ``positional_args`` is populated by `structlog.stdlib.BoundLogger` or
    can be set manually.

    The *remove_positional_args* flag can be set to `False` to keep the
    ``positional_args`` key in the event dict; by default it will be
    removed from the event dict after formatting a message.
    """

    def __init__(self, remove_positional_args: bool = True) -> None:
        self.remove_positional_args = remove_positional_args

    def __call__(
        self, _: WrappedLogger, __: str, event_dict: EventDict
    ) -> EventDict:
        args = event_dict.get("positional_args")

        # Mimic the formatting behaviour of the stdlib's logging module, which
        # accepts both positional arguments and a single dict argument. The
        # "single dict" check is the same one as the stdlib's logging module
        # performs in LogRecord.__init__().
        if args:
            if len(args) == 1 and isinstance(args[0], dict) and args[0]:
                args = args[0]

            event_dict["event"] %= args

        if self.remove_positional_args and args is not None:
            del event_dict["positional_args"]

        return event_dict


def filter_by_level(