Python 中 json 加載中的單引號和雙引號

Question

我注意到單引號導致simplejson的loads函數失敗：

>>> import simplejson as json
>>> json.loads("\"foo\"")
'foo'
>>> json.loads("\'foo\'")
Traceback (most recent call last):
...
ValueError: No JSON object could be decoded

我正在將文本文件中的foo = ["a", "b", "c"]解析為 Python 中的列表，並且還想接受foo = ['a', 'b', 'c'] . simplejson便於將foo自動生成列表。

如何在不破壞輸入的情況下讓loads接受單引號，或自動用雙引號替換單引號？ 謝謝。

Answer 1

使用適當的工具來完成這項工作，您不是在解析 JSON 而是 Python，因此請改用ast.literal_eval() ：

>>> import ast
>>> ast.literal_eval('["a", "b", "c"]')
['a', 'b', 'c']
>>> ast.literal_eval("['a', 'b', 'c']")
['a', 'b', 'c']
>>> ast.literal_eval('["mixed", \'quoting\', """styles"""]')
['mixed', 'quoting', 'styles']

• JSON 文檔總是對字符串使用雙引號，對\\uhhhh十六進制轉義語法使用 UTF-16，對鍵值對使用{...}對象，鍵總是字符串，序列總是[...]列表，並使用null ， true和false值; 注意小寫的布爾值。 數字有整數和浮點形式。

• 在 Python 中，字符串表示可以使用單引號和雙引號，Unicode 轉義使用\\uhhhh \\Uhhhhhhhh和\\Uhhhhhhhh形式（沒有 UTF-16 代理對），具有{...}顯示語法的字典可以具有許多不同類型的鍵，而不僅僅是字符串, 序列可以是列表 ( [...] )，但也可以使用元組 ( (...) )，或者您仍然可以使用其他容器類型。 Python 有None 、 True和False （標題大寫！），數字有整數、浮點數和復數形式。

當解碼碰巧成功但數據被錯誤解釋時，將一個與另一個混淆可能導致解析錯誤或微妙的問題，例如使用轉義的非 BMP 代碼點，例如表情符號。 確保使用正確的方法來解碼它們！ 並且在大多數情況下，當您確實擁有 Python 語法數據時，有人實際上使用了錯誤的編碼方法，並且只是意外地生成了 Python 表示。 在這種情況下，查看源是否需要修復； 通常輸出是通過使用str(object)產生的，其中json.dumps(obj)應該被使用。

Answer 2

當我想自己解決這個問題時，我從這個 StackOverflow 問題開始。

使用ast.literal_eval()的解決方案不適用於我的所有情況，因為文本偶爾也有布爾常量 true/false，它們不被識別為 Python 標記（大寫）。

為了自己解決這個問題，我編寫了一個自定義的 JSONDecoder ，它插入到標准的 json Python 包中。

pip install git+https://github.com/jpz/tolerantjsondecoder.git

也許這對下一個人有用。

另外，要注意的是，在我完成這個之后，我后來發現了demjson庫，它似乎是一個更完整的解決方案，但是我沒有對其進行評估。

Answer 3

Demjson 可以完成您的工作，但它非常慢，我的意思是與 simplejson 相比非常慢。 我不推薦它用於生產環境。

ast.literal_eval() 和 yaml 也不適用於所有 json，因此您需要更穩定的解決方案，例如 simplejson。

如果您稍微調整 simplejson，那么它就可以完成您的工作。 我自己已經完成並分享了這段代碼。

我分2點說

1) 從 github 下載 simplejson 並將其添加到您的項目中。 2）現在simplejson有decoder.py python文件。 用此代碼替換該文件代碼

"""Implementation of JSONDecoder
"""
from __future__ import absolute_import
import re
import sys
import struct
from .compat import u, text_type, binary_type, PY3, unichr
from .scanner import make_scanner, JSONDecodeError

def _import_c_scanstring():
    try:
        from ._speedups import scanstring
        return scanstring
    except ImportError:
        return None
c_scanstring = _import_c_scanstring()

# NOTE (3.1.0): JSONDecodeError may still be imported from this module for
# compatibility, but it was never in the __all__
__all__ = ['JSONDecoder']

FLAGS = re.VERBOSE | re.MULTILINE | re.DOTALL

def _floatconstants():
    if sys.version_info < (2, 6):
        _BYTES = '7FF80000000000007FF0000000000000'.decode('hex')
        nan, inf = struct.unpack('>dd', _BYTES)
    else:
        nan = float('nan')
        inf = float('inf')
    return nan, inf, -inf

NaN, PosInf, NegInf = _floatconstants()

_CONSTANTS = {
    '-Infinity': NegInf,
    'Infinity': PosInf,
    'NaN': NaN,
}

STRINGCHUNK = re.compile(r'(.*?)(["\\\x00-\x1f])', FLAGS)

# Changed Code Here. Added These Two Lines

STRINGCHUNKUNQUOTED = re.compile(r'(.*?)([:\\\x00-\x1f])', FLAGS)
STRINGCHUNKSINGLEQUOTED = re.compile(r"(.*?)(['\\\x00-\x1f])", FLAGS)

BACKSLASH = {
    '"': u('"'), '\\': u('\u005c'), '/': u('/'),
    'b': u('\b'), 'f': u('\f'), 'n': u('\n'), 'r': u('\r'), 't': u('\t'),
}
# Changed Code Here.
SINGLE_QUOTE_BACKSLASH = {
    "'": u("'"), '\\': u('\u005c'), '/': u('/'),
    'b': u('\b'), 'f': u('\f'), 'n': u('\n'), 'r': u('\r'), 't': u('\t'),
}

DEFAULT_ENCODING = "utf-8"

# Changed Code Here.
def parse_single_quoted_string(s, end, encoding=None, strict=True):
    return py_scanstring(s, end, encoding, strict, SINGLE_QUOTE_BACKSLASH, STRINGCHUNKSINGLEQUOTED.match)


def py_scanstring(s, end, encoding=None, strict=True,
        _b=BACKSLASH, _m=STRINGCHUNK.match, _join=u('').join,
        _PY3=PY3, _maxunicode=sys.maxunicode):
    """Scan the string s for a JSON string. End is the index of the
    character in s after the quote that started the JSON string.
    Unescapes all valid JSON string escape sequences and raises ValueError
    on attempt to decode an invalid string. If strict is False then literal
    control characters are allowed in the string.

    Returns a tuple of the decoded string and the index of the character in s
    after the end quote."""
    if encoding is None:
        encoding = DEFAULT_ENCODING
    chunks = []
    _append = chunks.append
    begin = end - 1
    while 1:
        chunk = _m(s, end)
        if chunk is None:
            raise JSONDecodeError(
                "Unterminated string starting at", s, begin)
        end = chunk.end()
        content, terminator = chunk.groups()
        # Content is contains zero or more unescaped string characters
        if content:
            if not _PY3 and not isinstance(content, text_type):
                content = text_type(content, encoding)
            _append(content)
        # Terminator is the end of string, a literal control character,
        # or a backslash denoting that an escape sequence follows

        # Changed Code Here.

        if not is_not_quote(terminator):
            break
        elif terminator != '\\':
            if strict:
                msg = "Invalid control character %r at"
                raise JSONDecodeError(msg, s, end)
            else:
                _append(terminator)
                continue
        try:
            esc = s[end]
        except IndexError:
            raise JSONDecodeError(
                "Unterminated string starting at", s, begin)
        # If not a unicode escape sequence, must be in the lookup table
        if esc != 'u':
            try:
                char = _b[esc]
            except KeyError:
                msg = "Invalid \\X escape sequence %r"
                raise JSONDecodeError(msg, s, end)
            end += 1
        else:
            # Unicode escape sequence
            msg = "Invalid \\uXXXX escape sequence"
            esc = s[end + 1:end + 5]
            escX = esc[1:2]
            if len(esc) != 4 or escX == 'x' or escX == 'X':
                raise JSONDecodeError(msg, s, end - 1)
            try:
                uni = int(esc, 16)
            except ValueError:
                raise JSONDecodeError(msg, s, end - 1)
            end += 5
            # Check for surrogate pair on UCS-4 systems
            # Note that this will join high/low surrogate pairs
            # but will also pass unpaired surrogates through
            if (_maxunicode > 65535 and
                uni & 0xfc00 == 0xd800 and
                s[end:end + 2] == '\\u'):
                esc2 = s[end + 2:end + 6]
                escX = esc2[1:2]
                if len(esc2) == 4 and not (escX == 'x' or escX == 'X'):
                    try:
                        uni2 = int(esc2, 16)
                    except ValueError:
                        raise JSONDecodeError(msg, s, end)
                    if uni2 & 0xfc00 == 0xdc00:
                        uni = 0x10000 + (((uni - 0xd800) << 10) |
                                         (uni2 - 0xdc00))
                        end += 6
            char = unichr(uni)
        # Append the unescaped character
        _append(char)
    return _join(chunks), end


# Use speedup if available
scanstring = c_scanstring or py_scanstring

WHITESPACE = re.compile(r'[ \t\n\r]*', FLAGS)
WHITESPACE_STR = ' \t\n\r'

# Changed Code Here.
UNQUOTEDDICT = {'/': '/', '\\': '\\', ';': ';', '#': '#',
            '=': '=', '{': '{', '}': '}', '[': '[', ']': ']',
            ':': ':', ',': ',', ' ': ' ', '\t': '\t',
            '\f': '\f', '\r': '\r', '\n': '\n'}

# Changed Code Here.
QUOTE_DICT = {'"': '"', "'": "'"}

# Changed Code Here.
def is_literal(char):
    return not UNQUOTEDDICT.get(char, None)

# Changed Code Here.
def is_not_quote(char):
    return not QUOTE_DICT.get(char, None)


# Changed Code Here.
def nexUnquotedKey(s, end):
    chunk = STRINGCHUNKUNQUOTED.match(s,end)
    for i in range(chunk.end()):
        index = i+end
        if not is_literal(s[index]):
            return s[end:index], index




def JSONObject(state, encoding, strict, scan_once, object_hook,
        object_pairs_hook, memo=None,
        _w=WHITESPACE.match, _ws=WHITESPACE_STR):
    (s, end) = state
    # Backwards compatibility
    if memo is None:
        memo = {}
    memo_get = memo.setdefault
    pairs = []
    # Use a slice to prevent IndexError from being raised, the following
    # check will raise a more specific ValueError if the string is empty
    nextchar = s[end:end + 1]
    # Normally we expect nextchar == '"'

    literal_check = False

    # Changed Code Here.
    if is_not_quote(nextchar):
        if nextchar in _ws:
            end = _w(s, end).end()
            nextchar = s[end:end + 1]
        # Trivial empty object
        literal_check = is_literal(nextchar)
        if nextchar == '}':
            if object_pairs_hook is not None:
                result = object_pairs_hook(pairs)
                return result, end + 1
            pairs = {}
            if object_hook is not None:
                pairs = object_hook(pairs)
            return pairs, end + 1
        elif nextchar != '"' and not literal_check:  # Changed Code Here.
            raise JSONDecodeError(
                "Expecting property name enclosed in double quotes",
                s, end)

    # Changed Code Here.
    if not literal_check:
        end += 1

    while True:
        if literal_check:
            key, end = nexUnquotedKey(s,end)
        else:
            # Changed Code Here.
            if nextchar == "'":
                key, end = scanstring(s, end, encoding, strict, SINGLE_QUOTE_BACKSLASH, STRINGCHUNKSINGLEQUOTED.match)
            else:
                key, end = scanstring(s, end, encoding, strict)

        key = memo_get(key, key)

        # To skip some function call overhead we optimize the fast paths where
        # the JSON key separator is ": " or just ":".
        if s[end:end + 1] != ':':
            end = _w(s, end).end()
            if s[end:end + 1] != ':':
                raise JSONDecodeError("Expecting ':' delimiter", s, end)

        end += 1

        try:
            if s[end] in _ws:
                end += 1
                if s[end] in _ws:
                    end = _w(s, end + 1).end()
        except IndexError:
            pass

        value, end = scan_once(s, end)
        pairs.append((key, value))

        try:
            nextchar = s[end]
            if nextchar in _ws:
                end = _w(s, end + 1).end()
                nextchar = s[end]
        except IndexError:
            nextchar = ''
        end += 1

        if nextchar == '}':
            break
        elif nextchar != ',':
            raise JSONDecodeError("Expecting ',' delimiter or '}'", s, end - 1)

        try:
            nextchar = s[end]
            if nextchar in _ws:
                end += 1
                nextchar = s[end]
                if nextchar in _ws:
                    end = _w(s, end + 1).end()
                    nextchar = s[end]
        except IndexError:
            nextchar = ''

        # Changed Code Here.
        if not literal_check:
            end += 1
            # Changed Code Here.
            if is_not_quote(nextchar):
                raise JSONDecodeError(
                    "Expecting property name enclosed in double quotes",
                    s, end - 1)

    if object_pairs_hook is not None:
        result = object_pairs_hook(pairs)
        return result, end
    pairs = dict(pairs)
    if object_hook is not None:
        pairs = object_hook(pairs)
    return pairs, end

def JSONArray(state, scan_once, _w=WHITESPACE.match, _ws=WHITESPACE_STR):
    (s, end) = state
    values = []
    nextchar = s[end:end + 1]
    if nextchar in _ws:
        end = _w(s, end + 1).end()
        nextchar = s[end:end + 1]
    # Look-ahead for trivial empty array
    if nextchar == ']':
        return values, end + 1
    elif nextchar == '':
        raise JSONDecodeError("Expecting value or ']'", s, end)
    _append = values.append
    while True:
        value, end = scan_once(s, end)
        _append(value)
        nextchar = s[end:end + 1]
        if nextchar in _ws:
            end = _w(s, end + 1).end()
            nextchar = s[end:end + 1]
        end += 1
        if nextchar == ']':
            break
        elif nextchar != ',':
            raise JSONDecodeError("Expecting ',' delimiter or ']'", s, end - 1)

        try:
            if s[end] in _ws:
                end += 1
                if s[end] in _ws:
                    end = _w(s, end + 1).end()
        except IndexError:
            pass

    return values, end

class JSONDecoder(object):
    """Simple JSON <http://json.org> decoder

    Performs the following translations in decoding by default:

    +---------------+-------------------+
    | JSON          | Python            |
    +===============+===================+
    | object        | dict              |
    +---------------+-------------------+
    | array         | list              |
    +---------------+-------------------+
    | string        | str, unicode      |
    +---------------+-------------------+
    | number (int)  | int, long         |
    +---------------+-------------------+
    | number (real) | float             |
    +---------------+-------------------+
    | true          | True              |
    +---------------+-------------------+
    | false         | False             |
    +---------------+-------------------+
    | null          | None              |
    +---------------+-------------------+

    It also understands ``NaN``, ``Infinity``, and ``-Infinity`` as
    their corresponding ``float`` values, which is outside the JSON spec.

    """

    def __init__(self, encoding=None, object_hook=None, parse_float=None,
            parse_int=None, parse_constant=None, strict=True,
            object_pairs_hook=None):
        """
        *encoding* determines the encoding used to interpret any
        :class:`str` objects decoded by this instance (``'utf-8'`` by
        default).  It has no effect when decoding :class:`unicode` objects.

        Note that currently only encodings that are a superset of ASCII work,
        strings of other encodings should be passed in as :class:`unicode`.

        *object_hook*, if specified, will be called with the result of every
        JSON object decoded and its return value will be used in place of the
        given :class:`dict`.  This can be used to provide custom
        deserializations (e.g. to support JSON-RPC class hinting).

        *object_pairs_hook* is an optional function that will be called with
        the result of any object literal decode with an ordered list of pairs.
        The return value of *object_pairs_hook* will be used instead of the
        :class:`dict`.  This feature can be used to implement custom decoders
        that rely on the order that the key and value pairs are decoded (for
        example, :func:`collections.OrderedDict` will remember the order of
        insertion). If *object_hook* is also defined, the *object_pairs_hook*
        takes priority.

        *parse_float*, if specified, will be called with the string of every
        JSON float to be decoded.  By default, this is equivalent to
        ``float(num_str)``. This can be used to use another datatype or parser
        for JSON floats (e.g. :class:`decimal.Decimal`).

        *parse_int*, if specified, will be called with the string of every
        JSON int to be decoded.  By default, this is equivalent to
        ``int(num_str)``.  This can be used to use another datatype or parser
        for JSON integers (e.g. :class:`float`).

        *parse_constant*, if specified, will be called with one of the
        following strings: ``'-Infinity'``, ``'Infinity'``, ``'NaN'``.  This
        can be used to raise an exception if invalid JSON numbers are
        encountered.

        *strict* controls the parser's behavior when it encounters an
        invalid control character in a string. The default setting of
        ``True`` means that unescaped control characters are parse errors, if
        ``False`` then control characters will be allowed in strings.

        """
        if encoding is None:
            encoding = DEFAULT_ENCODING
        self.encoding = encoding
        self.object_hook = object_hook
        self.object_pairs_hook = object_pairs_hook
        self.parse_float = parse_float or float
        self.parse_int = parse_int or int
        self.parse_constant = parse_constant or _CONSTANTS.__getitem__
        self.strict = strict
        self.parse_object = JSONObject
        self.parse_array = JSONArray
        self.parse_string = scanstring
        self.parse_single_quoted_string = parse_single_quoted_string  # Changed Code Here.
        self.memo = {}
        self.scan_once = make_scanner(self)

    def decode(self, s, _w=WHITESPACE.match, _PY3=PY3):
        """Return the Python representation of ``s`` (a ``str`` or ``unicode``
        instance containing a JSON document)

        """
        if _PY3 and isinstance(s, binary_type):
            s = s.decode(self.encoding)
        obj, end = self.raw_decode(s)
        end = _w(s, end).end()
        if end != len(s):
            raise JSONDecodeError("Extra data", s, end, len(s))
        return obj

    def raw_decode(self, s, idx=0, _w=WHITESPACE.match, _PY3=PY3):
        """Decode a JSON document from ``s`` (a ``str`` or ``unicode``
        beginning with a JSON document) and return a 2-tuple of the Python
        representation and the index in ``s`` where the document ended.
        Optionally, ``idx`` can be used to specify an offset in ``s`` where
        the JSON document begins.

        This can be used to decode a JSON document from a string that may
        have extraneous data at the end.

        """
        if idx < 0:
            # Ensure that raw_decode bails on negative indexes, the regex
            # would otherwise mask this behavior. #98
            raise JSONDecodeError('Expecting value', s, idx)
        if _PY3 and not isinstance(s, text_type):
            raise TypeError("Input string must be text, not bytes")
        # strip UTF-8 bom
        if len(s) > idx:
            ord0 = ord(s[idx])
            if ord0 == 0xfeff:
                idx += 1
            elif ord0 == 0xef and s[idx:idx + 3] == '\xef\xbb\xbf':
                idx += 3
        return self.scan_once(s, idx=_w(s, idx).end())

2) simplejson 有scanner.py python 文件。 用此代碼替換該文件代碼

 """JSON token scanner
"""
import re
from .errors import JSONDecodeError
def _import_c_make_scanner():
    try:
        from ._speedups import make_scanner
        return make_scanner
    except ImportError:
        return None
c_make_scanner = _import_c_make_scanner()

__all__ = ['make_scanner', 'JSONDecodeError']

NUMBER_RE = re.compile(
    r'(-?(?:0|[1-9]\d*))(\.\d+)?([eE][-+]?\d+)?',
    (re.VERBOSE | re.MULTILINE | re.DOTALL))


def py_make_scanner(context):
    parse_object = context.parse_object
    parse_array = context.parse_array
    parse_string = context.parse_string
    parse_single_quoted_string = context.parse_single_quoted_string  # Changed Code Here.
    match_number = NUMBER_RE.match
    encoding = context.encoding
    strict = context.strict
    parse_float = context.parse_float
    parse_int = context.parse_int
    parse_constant = context.parse_constant
    object_hook = context.object_hook
    object_pairs_hook = context.object_pairs_hook
    memo = context.memo

    def _scan_once(string, idx):
        errmsg = 'Expecting value'
        try:
            nextchar = string[idx]
        except IndexError:
            raise JSONDecodeError(errmsg, string, idx)

        if nextchar == '"':
            return parse_string(string, idx + 1, encoding, strict)
        elif nextchar == "'":
            return parse_single_quoted_string(string, idx + 1, encoding, strict)  # Changed Code Here.
        elif nextchar == '{':
            return parse_object((string, idx + 1), encoding, strict,
                _scan_once, object_hook, object_pairs_hook, memo)
        elif nextchar == '[':
            return parse_array((string, idx + 1), _scan_once)
        elif nextchar == 'n' and string[idx:idx + 4] == 'null':
            return None, idx + 4
        elif nextchar == 't' and string[idx:idx + 4] == 'true':
            return True, idx + 4
        elif nextchar == 'f' and string[idx:idx + 5] == 'false':
            return False, idx + 5

        m = match_number(string, idx)
        if m is not None:
            integer, frac, exp = m.groups()
            if frac or exp:
                res = parse_float(integer + (frac or '') + (exp or ''))
            else:
                res = parse_int(integer)
            return res, m.end()
        elif nextchar == 'N' and string[idx:idx + 3] == 'NaN':
            return parse_constant('NaN'), idx + 3
        elif nextchar == 'I' and string[idx:idx + 8] == 'Infinity':
            return parse_constant('Infinity'), idx + 8
        elif nextchar == '-' and string[idx:idx + 9] == '-Infinity':
            return parse_constant('-Infinity'), idx + 9
        else:
            raise JSONDecodeError(errmsg, string, idx)

    def scan_once(string, idx):
        if idx < 0:
            # Ensure the same behavior as the C speedup, otherwise
            # this would work for *some* negative string indices due
            # to the behavior of __getitem__ for strings. #98
            raise JSONDecodeError('Expecting value', string, idx)
        try:
            return _scan_once(string, idx)
        finally:
            memo.clear()

    return scan_once

make_scanner = c_make_scanner or py_make_scanner

現在你已經准備好了。 Simplejson 是我用過的最快、最穩定的庫。

我在 simplejson 中更改了幾行代碼，現在這個很棒的庫適用於

• 未加引號的 json 鍵和單引號的 json 字符串和鍵

我只更改了 python 代碼。 因此，如果您使用 C 擴展來加速提升，那么此代碼將不起作用。

無論我在哪里進行更改，我都會在此處添加注釋 # 更改代碼

我之前錯誤地以訪客用戶身份回答，現在我無法登錄編輯該答案，所以我在新線程中發布。