"""Utilities to manipulate JSON objects. """ #----------------------------------------------------------------------------- # Copyright (C) 2010-2011 The IPython Development Team # # Distributed under the terms of the BSD License. The full license is in # the file COPYING.txt, distributed as part of this software. #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Imports #----------------------------------------------------------------------------- # stdlib import math import re import types from datetime import datetime try: # base64.encodestring is deprecated in Python 3.x from base64 import encodebytes except ImportError: # Python 2.x from base64 import encodestring as encodebytes from IPython.utils import py3compat from IPython.utils.py3compat import string_types, unicode_type from IPython.utils.encoding import DEFAULT_ENCODING next_attr_name = '__next__' if py3compat.PY3 else 'next' #----------------------------------------------------------------------------- # Globals and constants #----------------------------------------------------------------------------- # timestamp formats ISO8601="%Y-%m-%dT%H:%M:%S.%f" ISO8601_PAT=re.compile(r"^(\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d+)Z?([\+\-]\d{2}:?\d{2})?$") #----------------------------------------------------------------------------- # Classes and functions #----------------------------------------------------------------------------- def rekey(dikt): """Rekey a dict that has been forced to use str keys where there should be ints by json.""" for k in dikt.iterkeys(): if isinstance(k, string_types): ik=fk=None try: ik = int(k) except ValueError: try: fk = float(k) except ValueError: continue if ik is not None: nk = ik else: nk = fk if nk in dikt: raise KeyError("already have key %r"%nk) dikt[nk] = dikt.pop(k) return dikt def extract_dates(obj): """extract ISO8601 dates from unpacked JSON""" if isinstance(obj, dict): obj = dict(obj) # don't clobber for k,v in obj.iteritems(): obj[k] = extract_dates(v) elif isinstance(obj, (list, tuple)): obj = [ extract_dates(o) for o in obj ] elif isinstance(obj, string_types): m = ISO8601_PAT.match(obj) if m: # FIXME: add actual timezone support # this just drops the timezone info notz = m.groups()[0] obj = datetime.strptime(notz, ISO8601) return obj def squash_dates(obj): """squash datetime objects into ISO8601 strings""" if isinstance(obj, dict): obj = dict(obj) # don't clobber for k,v in obj.iteritems(): obj[k] = squash_dates(v) elif isinstance(obj, (list, tuple)): obj = [ squash_dates(o) for o in obj ] elif isinstance(obj, datetime): obj = obj.isoformat() return obj def date_default(obj): """default function for packing datetime objects in JSON.""" if isinstance(obj, datetime): return obj.isoformat() else: raise TypeError("%r is not JSON serializable"%obj) # constants for identifying png/jpeg data PNG = b'\x89PNG\r\n\x1a\n' # front of PNG base64-encoded PNG64 = b'iVBORw0KG' JPEG = b'\xff\xd8' # front of JPEG base64-encoded JPEG64 = b'/9' def encode_images(format_dict): """b64-encodes images in a displaypub format dict Perhaps this should be handled in json_clean itself? Parameters ---------- format_dict : dict A dictionary of display data keyed by mime-type Returns ------- format_dict : dict A copy of the same dictionary, but binary image data ('image/png' or 'image/jpeg') is base64-encoded. """ encoded = format_dict.copy() pngdata = format_dict.get('image/png') if isinstance(pngdata, bytes): # make sure we don't double-encode if not pngdata.startswith(PNG64): pngdata = encodebytes(pngdata) encoded['image/png'] = pngdata.decode('ascii') jpegdata = format_dict.get('image/jpeg') if isinstance(jpegdata, bytes): # make sure we don't double-encode if not jpegdata.startswith(JPEG64): jpegdata = encodebytes(jpegdata) encoded['image/jpeg'] = jpegdata.decode('ascii') return encoded def json_clean(obj): """Clean an object to ensure it's safe to encode in JSON. Atomic, immutable objects are returned unmodified. Sets and tuples are converted to lists, lists are copied and dicts are also copied. Note: dicts whose keys could cause collisions upon encoding (such as a dict with both the number 1 and the string '1' as keys) will cause a ValueError to be raised. Parameters ---------- obj : any python object Returns ------- out : object A version of the input which will not cause an encoding error when encoded as JSON. Note that this function does not *encode* its inputs, it simply sanitizes it so that there will be no encoding errors later. Examples -------- >>> json_clean(4) 4 >>> json_clean(range(10)) [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] >>> sorted(json_clean(dict(x=1, y=2)).items()) [('x', 1), ('y', 2)] >>> sorted(json_clean(dict(x=1, y=2, z=[1,2,3])).items()) [('x', 1), ('y', 2), ('z', [1, 2, 3])] >>> json_clean(True) True """ # types that are 'atomic' and ok in json as-is. bool doesn't need to be # listed explicitly because bools pass as int instances atomic_ok = (unicode_type, int, types.NoneType) # containers that we need to convert into lists container_to_list = (tuple, set, types.GeneratorType) if isinstance(obj, float): # cast out-of-range floats to their reprs if math.isnan(obj) or math.isinf(obj): return repr(obj) return obj if isinstance(obj, atomic_ok): return obj if isinstance(obj, bytes): return obj.decode(DEFAULT_ENCODING, 'replace') if isinstance(obj, container_to_list) or ( hasattr(obj, '__iter__') and hasattr(obj, next_attr_name)): obj = list(obj) if isinstance(obj, list): return [json_clean(x) for x in obj] if isinstance(obj, dict): # First, validate that the dict won't lose data in conversion due to # key collisions after stringification. This can happen with keys like # True and 'true' or 1 and '1', which collide in JSON. nkeys = len(obj) nkeys_collapsed = len(set(map(str, obj))) if nkeys != nkeys_collapsed: raise ValueError('dict can not be safely converted to JSON: ' 'key collision would lead to dropped values') # If all OK, proceed by making the new dict that will be json-safe out = {} for k,v in obj.iteritems(): out[str(k)] = json_clean(v) return out # If we get here, we don't know how to handle the object, so we just get # its repr and return that. This will catch lambdas, open sockets, class # objects, and any other complicated contraption that json can't encode return repr(obj)