243 lines
7.9 KiB
Python
243 lines
7.9 KiB
Python
# -*- coding: utf-8 -*-
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"""
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flask.jsonimpl
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~~~~~~~~~~~~~~
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Implementation helpers for the JSON support in Flask.
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:copyright: (c) 2012 by Armin Ronacher.
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:license: BSD, see LICENSE for more details.
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"""
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import io
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import uuid
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from datetime import datetime
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from .globals import current_app, request
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from ._compat import text_type, PY2
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from werkzeug.http import http_date
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from jinja2 import Markup
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# Use the same json implementation as itsdangerous on which we
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# depend anyways.
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try:
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from itsdangerous import simplejson as _json
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except ImportError:
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from itsdangerous import json as _json
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# figure out if simplejson escapes slashes. This behavior was changed
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# from one version to another without reason.
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_slash_escape = '\\/' not in _json.dumps('/')
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__all__ = ['dump', 'dumps', 'load', 'loads', 'htmlsafe_dump',
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'htmlsafe_dumps', 'JSONDecoder', 'JSONEncoder',
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'jsonify']
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def _wrap_reader_for_text(fp, encoding):
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if isinstance(fp.read(0), bytes):
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fp = io.TextIOWrapper(io.BufferedReader(fp), encoding)
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return fp
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def _wrap_writer_for_text(fp, encoding):
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try:
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fp.write('')
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except TypeError:
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fp = io.TextIOWrapper(fp, encoding)
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return fp
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class JSONEncoder(_json.JSONEncoder):
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"""The default Flask JSON encoder. This one extends the default simplejson
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encoder by also supporting ``datetime`` objects, ``UUID`` as well as
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``Markup`` objects which are serialized as RFC 822 datetime strings (same
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as the HTTP date format). In order to support more data types override the
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:meth:`default` method.
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"""
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def default(self, o):
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"""Implement this method in a subclass such that it returns a
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serializable object for ``o``, or calls the base implementation (to
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raise a ``TypeError``).
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For example, to support arbitrary iterators, you could implement
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default like this::
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def default(self, o):
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try:
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iterable = iter(o)
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except TypeError:
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pass
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else:
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return list(iterable)
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return JSONEncoder.default(self, o)
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"""
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if isinstance(o, datetime):
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return http_date(o)
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if isinstance(o, uuid.UUID):
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return str(o)
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if hasattr(o, '__html__'):
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return text_type(o.__html__())
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return _json.JSONEncoder.default(self, o)
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class JSONDecoder(_json.JSONDecoder):
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"""The default JSON decoder. This one does not change the behavior from
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the default simplejson encoder. Consult the :mod:`json` documentation
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for more information. This decoder is not only used for the load
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functions of this module but also :attr:`~flask.Request`.
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"""
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def _dump_arg_defaults(kwargs):
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"""Inject default arguments for dump functions."""
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if current_app:
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kwargs.setdefault('cls', current_app.json_encoder)
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if not current_app.config['JSON_AS_ASCII']:
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kwargs.setdefault('ensure_ascii', False)
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kwargs.setdefault('sort_keys', current_app.config['JSON_SORT_KEYS'])
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else:
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kwargs.setdefault('sort_keys', True)
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kwargs.setdefault('cls', JSONEncoder)
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def _load_arg_defaults(kwargs):
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"""Inject default arguments for load functions."""
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if current_app:
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kwargs.setdefault('cls', current_app.json_decoder)
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else:
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kwargs.setdefault('cls', JSONDecoder)
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def dumps(obj, **kwargs):
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"""Serialize ``obj`` to a JSON formatted ``str`` by using the application's
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configured encoder (:attr:`~flask.Flask.json_encoder`) if there is an
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application on the stack.
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This function can return ``unicode`` strings or ascii-only bytestrings by
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default which coerce into unicode strings automatically. That behavior by
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default is controlled by the ``JSON_AS_ASCII`` configuration variable
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and can be overriden by the simplejson ``ensure_ascii`` parameter.
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"""
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_dump_arg_defaults(kwargs)
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encoding = kwargs.pop('encoding', None)
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rv = _json.dumps(obj, **kwargs)
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if encoding is not None and isinstance(rv, text_type):
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rv = rv.encode(encoding)
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return rv
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def dump(obj, fp, **kwargs):
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"""Like :func:`dumps` but writes into a file object."""
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_dump_arg_defaults(kwargs)
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encoding = kwargs.pop('encoding', None)
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if encoding is not None:
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fp = _wrap_writer_for_text(fp, encoding)
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_json.dump(obj, fp, **kwargs)
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def loads(s, **kwargs):
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"""Unserialize a JSON object from a string ``s`` by using the application's
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configured decoder (:attr:`~flask.Flask.json_decoder`) if there is an
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application on the stack.
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"""
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_load_arg_defaults(kwargs)
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if isinstance(s, bytes):
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s = s.decode(kwargs.pop('encoding', None) or 'utf-8')
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return _json.loads(s, **kwargs)
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def load(fp, **kwargs):
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"""Like :func:`loads` but reads from a file object.
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"""
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_load_arg_defaults(kwargs)
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if not PY2:
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fp = _wrap_reader_for_text(fp, kwargs.pop('encoding', None) or 'utf-8')
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return _json.load(fp, **kwargs)
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def htmlsafe_dumps(obj, **kwargs):
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"""Works exactly like :func:`dumps` but is safe for use in ``<script>``
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tags. It accepts the same arguments and returns a JSON string. Note that
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this is available in templates through the ``|tojson`` filter which will
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also mark the result as safe. Due to how this function escapes certain
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characters this is safe even if used outside of ``<script>`` tags.
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The following characters are escaped in strings:
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- ``<``
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- ``>``
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- ``&``
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- ``'``
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This makes it safe to embed such strings in any place in HTML with the
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notable exception of double quoted attributes. In that case single
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quote your attributes or HTML escape it in addition.
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.. versionchanged:: 0.10
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This function's return value is now always safe for HTML usage, even
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if outside of script tags or if used in XHTML. This rule does not
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hold true when using this function in HTML attributes that are double
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quoted. Always single quote attributes if you use the ``|tojson``
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filter. Alternatively use ``|tojson|forceescape``.
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"""
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rv = dumps(obj, **kwargs) \
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.replace(u'<', u'\\u003c') \
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.replace(u'>', u'\\u003e') \
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.replace(u'&', u'\\u0026') \
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.replace(u"'", u'\\u0027')
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if not _slash_escape:
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rv = rv.replace('\\/', '/')
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return rv
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def htmlsafe_dump(obj, fp, **kwargs):
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"""Like :func:`htmlsafe_dumps` but writes into a file object."""
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fp.write(unicode(htmlsafe_dumps(obj, **kwargs)))
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def jsonify(*args, **kwargs):
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"""Creates a :class:`~flask.Response` with the JSON representation of
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the given arguments with an `application/json` mimetype. The arguments
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to this function are the same as to the :class:`dict` constructor.
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Example usage::
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from flask import jsonify
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@app.route('/_get_current_user')
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def get_current_user():
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return jsonify(username=g.user.username,
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email=g.user.email,
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id=g.user.id)
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This will send a JSON response like this to the browser::
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{
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"username": "admin",
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"email": "admin@localhost",
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"id": 42
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}
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For security reasons only objects are supported toplevel. For more
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information about this, have a look at :ref:`json-security`.
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This function's response will be pretty printed if it was not requested
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with ``X-Requested-With: XMLHttpRequest`` to simplify debugging unless
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the ``JSONIFY_PRETTYPRINT_REGULAR`` config parameter is set to false.
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.. versionadded:: 0.2
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"""
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indent = None
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if current_app.config['JSONIFY_PRETTYPRINT_REGULAR'] \
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and not request.is_xhr:
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indent = 2
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return current_app.response_class(dumps(dict(*args, **kwargs),
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indent=indent),
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mimetype='application/json')
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def tojson_filter(obj, **kwargs):
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return Markup(htmlsafe_dumps(obj, **kwargs))
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