如何将 namedtuple 序列化为JSON并保留字段名？
将 namedtuple 序列化为 JSON 时，只有值被序列化，字段名称会丢失。我希望在进行 JSON 序列化时也能够保留字段名，因此我执行了以下操作：
class foobar(namedtuple('f', 'foo, bar')):
__slots__ = ()
def __iter__(self):
yield self._asdict()
上述内容在序列化成JSON后符合我的预期，并在我使用时（如属性访问等）与namedtuple一样工作，除了在迭代时出现非元组结果的情况（对于我的用例来说没问题）。
有没有将字段名保留转换为JSON的“正确方法”？
NamedTuple的任何私有或内部特性，因为它们以前已经发生过变化，并且将来还会再次变化。例如，如果你的NamedTuple是一个平面值对象，你只关心将其序列化而不关心它嵌套到另一个对象中的情况，那么你可以避免使用__dict__被删除或_as_dict()改变所带来的麻烦，只需做类似以下的事情（是Python 3，因为这个答案是针对现在的）：from typing import NamedTuple
class ApiListRequest(NamedTuple):
group: str="default"
filter: str="*"
def to_dict(self):
return {
'group': self.group,
'filter': self.filter,
}
def to_json(self):
return json.dumps(self.to_dict())
dumps的default可调用kwarg，以便在可能的情况下执行to_dict()调用，但由于NamedTuple可以转换为列表，因此未被调用。_asdict是namedtuple公共API的一部分。它们解释了下划线的原因。除了继承自元组的方法外，命名元组还支持三个额外的方法和两个属性。为了避免与字段名称发生冲突，方法和属性名称以下划线开头。 - quant_dev我知道这是一个非常旧的线程，但对于这个问题，我想到的一个解决办法是使用类似的自定义方法来修补或覆盖函数json.encoder._make_iterencode，并在其中扩展以单独处理命名元组。我不确定这是否是一个好的做法，或者是否有一种更安全的标准方法来进行修补：
def _make_iterencode(markers, _default, _encoder, _indent, _floatstr,
_key_separator, _item_separator, _sort_keys, _skipkeys, _one_shot,
ValueError=ValueError,
dict=dict,
float=float,
id=id,
int=int,
isinstance=isinstance,
list=list,
str=str,
tuple=tuple,
_intstr=int.__repr__,
):
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):
# Subclasses of int/float may override __repr__, but we still
# want to encode them as integers/floats in JSON. One example
# within the standard library is IntEnum.
yield buf + _intstr(value)
elif isinstance(value, float):
# see comment above for int
yield buf + _floatstr(value)
else:
yield buf
# EDIT
##################
if isinstance(value, tuple) and hasattr(value, '_asdict'):
value = value._asdict()
chunks = _iterencode_dict(value, _current_indent_level)
##################
elif 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)
yield from chunks
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())
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):
# see comment for int/float in _make_iterencode
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):
# see comment for int/float in _make_iterencode
key = _intstr(key)
elif _skipkeys:
continue
else:
raise TypeError(f'keys must be str, int, float, bool or None, '
f'not {key.__class__.__name__}')
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):
# see comment for int/float in _make_iterencode
yield _intstr(value)
elif isinstance(value, float):
# see comment for int/float in _make_iterencode
yield _floatstr(value)
else:
# EDIT
###############
if isinstance(value, tuple) and hasattr(value, '_asdict'):
value = value._asdict()
chunks = _iterencode_dict(value, _current_indent_level)
###############
elif 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)
yield from chunks
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):
# see comment for int/float in _make_iterencode
yield _intstr(o)
elif isinstance(o, float):
# see comment for int/float in _make_iterencode
yield _floatstr(o)
# EDIT
##################
elif isinstance(o, tuple) and hasattr(o, '_asdict'):
o = o._asdict()
yield from _iterencode_dict(o, _current_indent_level)
##################
elif isinstance(o, (list, tuple)):
yield from _iterencode_list(o, _current_indent_level)
elif isinstance(o, dict):
yield from _iterencode_dict(o, _current_indent_level)
else:
if markers is not None:
markerid = id(o)
if markerid in markers:
raise ValueError("Circular reference detected")
markers[markerid] = o
o = _default(o)
yield from _iterencode(o, _current_indent_level)
if markers is not None:
del markers[markerid]
return _iterencode
# alters the json lib
json.encoder._make_iterencode = _make_iterencode