json.py
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from __future__ import absolute_import
import datetime
import uuid
from .._compat import text_type
from ..exceptions import BadRequest
from ..utils import detect_utf_encoding
try:
import simplejson as _json
except ImportError:
import json as _json
class _JSONModule(object):
@staticmethod
def _default(o):
if isinstance(o, datetime.date):
return o.isoformat()
if isinstance(o, uuid.UUID):
return str(o)
if hasattr(o, "__html__"):
return text_type(o.__html__())
raise TypeError()
@classmethod
def dumps(cls, obj, **kw):
kw.setdefault("separators", (",", ":"))
kw.setdefault("default", cls._default)
kw.setdefault("sort_keys", True)
return _json.dumps(obj, **kw)
@staticmethod
def loads(s, **kw):
if isinstance(s, bytes):
# Needed for Python < 3.6
encoding = detect_utf_encoding(s)
s = s.decode(encoding)
return _json.loads(s, **kw)
class JSONMixin(object):
"""Mixin to parse :attr:`data` as JSON. Can be mixed in for both
:class:`~werkzeug.wrappers.Request` and
:class:`~werkzeug.wrappers.Response` classes.
If `simplejson`_ is installed it is preferred over Python's built-in
:mod:`json` module.
.. _simplejson: https://simplejson.readthedocs.io/en/latest/
"""
#: A module or other object that has ``dumps`` and ``loads``
#: functions that match the API of the built-in :mod:`json` module.
json_module = _JSONModule
@property
def json(self):
"""The parsed JSON data if :attr:`mimetype` indicates JSON
(:mimetype:`application/json`, see :meth:`is_json`).
Calls :meth:`get_json` with default arguments.
"""
return self.get_json()
@property
def is_json(self):
"""Check if the mimetype indicates JSON data, either
:mimetype:`application/json` or :mimetype:`application/*+json`.
"""
mt = self.mimetype
return (
mt == "application/json"
or mt.startswith("application/")
and mt.endswith("+json")
)
def _get_data_for_json(self, cache):
try:
return self.get_data(cache=cache)
except TypeError:
# Response doesn't have cache param.
return self.get_data()
# Cached values for ``(silent=False, silent=True)``. Initialized
# with sentinel values.
_cached_json = (Ellipsis, Ellipsis)
def get_json(self, force=False, silent=False, cache=True):
"""Parse :attr:`data` as JSON.
If the mimetype does not indicate JSON
(:mimetype:`application/json`, see :meth:`is_json`), this
returns ``None``.
If parsing fails, :meth:`on_json_loading_failed` is called and
its return value is used as the return value.
:param force: Ignore the mimetype and always try to parse JSON.
:param silent: Silence parsing errors and return ``None``
instead.
:param cache: Store the parsed JSON to return for subsequent
calls.
"""
if cache and self._cached_json[silent] is not Ellipsis:
return self._cached_json[silent]
if not (force or self.is_json):
return None
data = self._get_data_for_json(cache=cache)
try:
rv = self.json_module.loads(data)
except ValueError as e:
if silent:
rv = None
if cache:
normal_rv, _ = self._cached_json
self._cached_json = (normal_rv, rv)
else:
rv = self.on_json_loading_failed(e)
if cache:
_, silent_rv = self._cached_json
self._cached_json = (rv, silent_rv)
else:
if cache:
self._cached_json = (rv, rv)
return rv
def on_json_loading_failed(self, e):
"""Called if :meth:`get_json` parsing fails and isn't silenced.
If this method returns a value, it is used as the return value
for :meth:`get_json`. The default implementation raises
:exc:`~werkzeug.exceptions.BadRequest`.
"""
raise BadRequest("Failed to decode JSON object: {0}".format(e))