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import zlib
from ._json import _CompactJSON
from .encoding import base64_decode
from .encoding import base64_encode
from .exc import BadPayload
from .serializer import Serializer
from .timed import TimedSerializer
class URLSafeSerializerMixin(object):
"""Mixed in with a regular serializer it will attempt to zlib
compress the string to make it shorter if necessary. It will also
base64 encode the string so that it can safely be placed in a URL.
"""
default_serializer = _CompactJSON
def load_payload(self, payload, *args, **kwargs):
decompress = False
if payload.startswith(b"."):
payload = payload[1:]
decompress = True
try:
json = base64_decode(payload)
except Exception as e:
raise BadPayload(
"Could not base64 decode the payload because of an exception",
original_error=e,
)
if decompress:
try:
json = zlib.decompress(json)
except Exception as e:
raise BadPayload(
"Could not zlib decompress the payload before decoding the payload",
original_error=e,
)
return super(URLSafeSerializerMixin, self).load_payload(json, *args, **kwargs)
def dump_payload(self, obj):
json = super(URLSafeSerializerMixin, self).dump_payload(obj)
is_compressed = False
compressed = zlib.compress(json)
if len(compressed) < (len(json) - 1):
json = compressed
is_compressed = True
base64d = base64_encode(json)
if is_compressed:
base64d = b"." + base64d
return base64d
class URLSafeSerializer(URLSafeSerializerMixin, Serializer):
"""Works like :class:`.Serializer` but dumps and loads into a URL
safe string consisting of the upper and lowercase character of the
alphabet as well as ``'_'``, ``'-'`` and ``'.'``.
"""
class URLSafeTimedSerializer(URLSafeSerializerMixin, TimedSerializer):
"""Works like :class:`.TimedSerializer` but dumps and loads into a
URL safe string consisting of the upper and lowercase character of
the alphabet as well as ``'_'``, ``'-'`` and ``'.'``.
"""
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