python - 自定义 simplejson 输出

Question

我使用 simplejson 转换 python dicts，但我想为一些定义的键自定义输出。

例如，我想要 key callback和 scope始终使用 呈现没有周围的报价 所以javascript可以解释数据而不是将其作为字符串读取。

示例所需的输出:

"data":{
    "name":"Julien"
    ,"callback":function() {alert('hello, world');}
    ,"params":{
       "target":"div2"
       ,"scope":this
     }
}

注意 callback和 scope键的值中没有周围的引号。

我试过创建一个自定义类和子类 JSONencoder ，但没有运气。

class JsonSpecialKey(object):
    def __init__(self, data):
        self.data = data

class JsonSpecialEncoder(simplejson.JSONEncoder):
     def default(self, obj):
        if isinstance (obj, JsonSpecialKey):
            # how to remove quotes ??
            return obj.data
        return simplejson.JSONEncoder.default(self, obj)

d = {'testKey':JsonSpecialKey('function() {alert(123);}')}
print simplejson.dumps(d, cls=JsonSpecialEncoder, ensure_ascii=False, indent=4)

我知道生成的 JSON 在 JSON 建议中可能无效，但它对某些 JS 应用程序很重要。

我已经尝试了一些正则表达式的解决方法，但是对于多行和带有数据的内联函数来说变得越来越复杂。

谢谢 !

Answer 1

我通过修改json代码成功

import json
from json.encoder import encode_basestring_ascii ,encode_basestring,FLOAT_REPR,INFINITY,c_make_encoder
class JsonSpecialKey(object):
    def __init__(self, data):
        self.data = data
def _make_iterencode(markers, _default, _encoder, _indent, _floatstr,
        _key_separator, _item_separator, _sort_keys, _skipkeys, _one_shot,
        ## HACK: hand-optimized bytecode; turn globals into locals
        ValueError=ValueError,
        dict=dict,
        float=float,
        id=id,
        int=int,
        isinstance=isinstance,
        list=list,
        str=str,
        tuple=tuple,
    ):

    if _indent is not None and not isinstance(_indent, str):
        _indent = ' ' * _indent

    def _iterencode_list(lst, _current_indent_level):
        if not lst:
            yield '[]'
            return
        if markers is not None:
            markerid = id(lst)
            if markerid in markers:
                raise ValueError("Circular reference detected")
            markers[markerid] = lst
        buf = '['
        if _indent is not None:
            _current_indent_level += 1
            newline_indent = '\n' + _indent * _current_indent_level
            separator = _item_separator + newline_indent
            buf += newline_indent
        else:
            newline_indent = None
            separator = _item_separator
        first = True
        for value in lst:
            if first:
                first = False
            else:
                buf = separator
            if isinstance(value, str):
                yield buf + _encoder(value)
            elif value is None:
                yield buf + 'null'
            elif value is True:
                yield buf + 'true'
            elif value is False:
                yield buf + 'false'
            elif isinstance(value, int):
                yield buf + str(value)
            elif isinstance(value, float):
                yield buf + _floatstr(value)
            elif isinstance(value, JsonSpecialKey):
                yield buf + value.data

            else:
                yield buf
                if isinstance(value, (list, tuple)):
                    chunks = _iterencode_list(value, _current_indent_level)
                elif isinstance(value, dict):
                    chunks = _iterencode_dict(value, _current_indent_level)
                else:
                    chunks = _iterencode(value, _current_indent_level)
                for chunk in chunks:
                    yield chunk
        if newline_indent is not None:
            _current_indent_level -= 1
            yield '\n' + _indent * _current_indent_level
        yield ']'
        if markers is not None:
            del markers[markerid]

    def _iterencode_dict(dct, _current_indent_level):
        if not dct:
            yield '{}'
            return
        if markers is not None:
            markerid = id(dct)
            if markerid in markers:
                raise ValueError("Circular reference detected")
            markers[markerid] = dct
        yield '{'
        if _indent is not None:
            _current_indent_level += 1
            newline_indent = '\n' + _indent * _current_indent_level
            item_separator = _item_separator + newline_indent
            yield newline_indent
        else:
            newline_indent = None
            item_separator = _item_separator
        first = True
        if _sort_keys:
            items = sorted(dct.items(), key=lambda kv: kv[0])
        else:
            items = dct.items()
        for key, value in items:
            if isinstance(key, str):
                pass
            # JavaScript is weakly typed for these, so it makes sense to
            # also allow them.  Many encoders seem to do something like this.
            elif isinstance(key, float):
                key = _floatstr(key)
            elif key is True:
                key = 'true'
            elif key is False:
                key = 'false'
            elif key is None:
                key = 'null'
            elif isinstance(key, int):
                key = str(key)
            elif _skipkeys:
                continue
            else:
                raise TypeError("key " + repr(key) + " is not a string")
            if first:
                first = False
            else:
                yield item_separator
            yield _encoder(key)
            yield _key_separator
            if isinstance(value, str):
                yield _encoder(value)
            elif value is None:
                yield 'null'
            elif value is True:
                yield 'true'
            elif value is False:
                yield 'false'
            elif isinstance(value, int):
                yield str(value)
            elif isinstance(value, float):
                yield _floatstr(value)
            elif isinstance(value, JsonSpecialKey):
                yield value.data
            else:
                if isinstance(value, (list, tuple)):
                    chunks = _iterencode_list(value, _current_indent_level)
                elif isinstance(value, dict):
                    chunks = _iterencode_dict(value, _current_indent_level)
                else:
                    chunks = _iterencode(value, _current_indent_level)
                for chunk in chunks:
                    yield chunk
        if newline_indent is not None:
            _current_indent_level -= 1
            yield '\n' + _indent * _current_indent_level
        yield '}'
        if markers is not None:
            del markers[markerid]

    def _iterencode(o, _current_indent_level):
        if isinstance(o, str):
            yield _encoder(o)
        elif o is None:
            yield 'null'
        elif o is True:
            yield 'true'
        elif o is False:
            yield 'false'
        elif isinstance(o, int):
            yield str(o)
        elif isinstance(o, float):
            yield _floatstr(o)
        elif isinstance(o, JsonSpecialKey):
            yield o.data
        elif isinstance(o, (list, tuple)):
            for chunk in _iterencode_list(o, _current_indent_level):
                yield chunk
        elif isinstance(o, dict):
            for chunk in _iterencode_dict(o, _current_indent_level):
                yield chunk
        else:
            if markers is not None:
                markerid = id(o)
                if markerid in markers:
                    raise ValueError("Circular reference detected")
                markers[markerid] = o
            o = _default(o)
            for chunk in _iterencode(o, _current_indent_level):
                yield chunk
            if markers is not None:
                del markers[markerid]
    return _iterencode
class JsonSpecialEncoder(json.JSONEncoder):


     def iterencode(self, o, _one_shot=False):
        """Encode the given object and yield each string
        representation as available.

        For example::

            for chunk in JSONEncoder().iterencode(bigobject):
                mysocket.write(chunk)

        """
        if self.check_circular:
            markers = {}
        else:
            markers = None
        if self.ensure_ascii:
            _encoder = encode_basestring_ascii
        else:
            _encoder = encode_basestring
        def floatstr(o, allow_nan=self.allow_nan,
                _repr=FLOAT_REPR, _inf=INFINITY, _neginf=-INFINITY):
            # Check for specials.  Note that this type of test is processor
            # and/or platform-specific, so do tests which don't depend on the
            # internals.

            if o != o:
                text = 'NaN'
            elif o == _inf:
                text = 'Infinity'
            elif o == _neginf:
                text = '-Infinity'
            else:
                return _repr(o)

            if not allow_nan:
                raise ValueError(
                    "Out of range float values are not JSON compliant: " +
                    repr(o))

            return text



        _iterencode = _make_iterencode(
            markers, self.default, _encoder, self.indent, floatstr,
            self.key_separator, self.item_separator, self.sort_keys,
            self.skipkeys, _one_shot)
        return _iterencode(o, 0)
d = {'testKey':JsonSpecialKey('function() {alert(123);}')}
print (json.dumps(d, cls=JsonSpecialEncoder, ensure_ascii=False, indent=4))

编辑:我修改的代码的精度

来自 json.encode我拿了函数_make_iterencode
添加类似的东西

       elif isinstance(value, JsonSpecialKey):
            yield buf + value.data

在三个地方

来自 JsonEncoder我采取的方法iterencode但我只是强制了 _iterencode成为我的自定义函数 _make_iterencode

 _iterencode = _make_iterencode(
        markers, self.default, _encoder, self.indent, floatstr,
        self.key_separator, self.item_separator, self.sort_keys,
        self.skipkeys, _one_shot)

我希望很清楚