Function parse_options_header

src/werkzeug/http.py:455–607

Parse a header that consists of a value with ``key=value`` parameters separated by semicolons ``;``. For example, the ``Content-Type`` header. .. code-block:: python parse_options_header("text/html; charset=UTF-8") ('text/html', {'charset': 'UTF-8'}) parse_options_

(value: str | None)

def parse_options_header(value: str | None) -> tuple[str, dict[str, str]]:
    """Parse a header that consists of a value with ``key=value`` parameters separated
    by semicolons ``;``. For example, the ``Content-Type`` header.

    .. code-block:: python

        parse_options_header("text/html; charset=UTF-8")
        ('text/html', {'charset': 'UTF-8'})

        parse_options_header("")
        ("", {})

    This is the reverse of :func:`dump_options_header`.

    This parses valid parameter parts as described in
    `RFC 9110 <https://httpwg.org/specs/rfc9110.html#parameter>`__. Invalid parts are
    skipped.

    This handles continuations and charsets as described in
    `RFC 2231 <https://www.rfc-editor.org/rfc/rfc2231#section-3>`__, although not as
    strictly as the RFC. Only ASCII, UTF-8, and ISO-8859-1 charsets are accepted,
    otherwise the value remains quoted.

    Clients may not be consistent in how they handle a quote character within a quoted
    value. The `HTML Standard <https://html.spec.whatwg.org/#multipart-form-data>`__
    replaces it with ``%22`` in multipart form data.
    `RFC 9110 <https://httpwg.org/specs/rfc9110.html#quoted.strings>`__ uses backslash
    escapes in HTTP headers. Both are decoded to the ``"`` character.

    Clients may not be consistent in how they handle non-ASCII characters. HTML
    documents must declare ``<meta charset=UTF-8>``, otherwise browsers may replace with
    HTML character references, which can be decoded using :func:`html.unescape`.

    :param value: The header value to parse.
    :return: ``(value, options)``, where ``options`` is a dict

    .. versionchanged:: 2.3
        Invalid parts, such as keys with no value, quoted keys, and incorrectly quoted
        values, are discarded instead of treating as ``None``.

    .. versionchanged:: 2.3
        Only ASCII, UTF-8, and ISO-8859-1 are accepted for charset values.

    .. versionchanged:: 2.3
        Escaped quotes in quoted values, like ``%22`` and ``\\"``, are handled.

    .. versionchanged:: 2.2
        Option names are always converted to lowercase.

    .. versionchanged:: 2.2
        The ``multiple`` parameter was removed.

    .. versionchanged:: 0.15
        :rfc:`2231` parameter continuations are handled.

    .. versionadded:: 0.5
    """
    if value is None: