tag.py — flask Source File

Source Code

"""
Tagged JSON
~~~~~~~~~~~

A compact representation for lossless serialization of non-standard JSON
types. :class:`~flask.sessions.SecureCookieSessionInterface` uses this
to serialize the session data, but it may be useful in other places. It
can be extended to support other types.

.. autoclass:: TaggedJSONSerializer
    :members:

.. autoclass:: JSONTag
    :members:

Let's see an example that adds support for
:class:`~collections.OrderedDict`. Dicts don't have an order in JSON, so
to handle this we will dump the items as a list of ``[key, value]``
pairs. Subclass :class:`JSONTag` and give it the new key ``' od'`` to
identify the type. The session serializer processes dicts first, so
insert the new tag at the front of the order since ``OrderedDict`` must
be processed before ``dict``.

.. code-block:: python

    from flask.json.tag import JSONTag

    class TagOrderedDict(JSONTag):
        __slots__ = ('serializer',)
        key = ' od'

        def check(self, value):
            return isinstance(value, OrderedDict)

        def to_json(self, value):
            return [[k, self.serializer.tag(v)] for k, v in iteritems(value)]

        def to_python(self, value):
            return OrderedDict(value)

    app.session_interface.serializer.register(TagOrderedDict, index=0)
"""

from __future__ import annotations

import typing as t
from base64 import b64decode
from base64 import b64encode
from datetime import datetime
from uuid import UUID

from markupsafe import Markup
from werkzeug.http import http_date
from werkzeug.http import parse_date

from ..json import dumps
from ..json import loads


class JSONTag:
// ... (268 more lines)