除了使用外部库(例如 jsonpickle,虽然我没有尝试过),是否有一种方法可以让 Python 的 json
模块将具有循环引用的字典(或列表等)进行转储(只是删除引用)?
我只想使用 json 更轻松地查看一些调试输出。
除了使用外部库(例如 jsonpickle,虽然我没有尝试过),是否有一种方法可以让 Python 的 json
模块将具有循环引用的字典(或列表等)进行转储(只是删除引用)?
我只想使用 json 更轻松地查看一些调试输出。
好的,避免使用除标准模块以外的任何东西,这里有一个解决方案,它利用repr
来处理循环引用。编辑:最新版本请参见多用途函数,可将任何Python对象以大部分可读的方式转储(也称为dump)
# MAGIC-NUMBER: max length is just some guess at a reasonable size, e.g. 80 cols by 100 lines
def dump(value, msg='DUMP', max_length=80 * 100, stdout=False, pick=None):
"""
Write as verbose of a description of the value as possible to logging.DEBUG.
See https://dev59.com/9obca4cB1Zd3GeqPZLN6
:param value: The item of interest.
:type value: object
:param msg: Prefix for the logged item (default='DUMP')
:type msg: basestring
:param max_length: Longest allowed string length (set to None for unlimited)
:type max_length: int
:param stdout: If true, print instead of logging (default=False)
:type stdout: bool
:param pick: If specified, dump only values for these keys of the item
(value must be a dict or allow __dict__ access).
The name comes from http://underscorejs.org/#pick.
:type pick: iterable of basestring
:return: True if message dumped
:rtype: bool
"""
if not logging.getLogger().isEnabledFor(logging.DEBUG) and not stdout:
return
if pick:
d = value if isinstance(value, dict) else value.__dict__
filtered = {
property_name: d[property_name]
for property_name in pick
if property_name in d
}
value = filtered
kwargs = dict(indent=2, sort_keys=True)
try:
import json
info = json.dumps(value, **kwargs)
except:
# JSON doesn't like circular references :/
try:
string_repr = repr(value)
# Replace python primitives, single-quotes, unicode, etc
string_repr = string_repr\
.replace('None', 'null')\
.replace('True', 'true')\
.replace('False', 'false')\
.replace("u'", "'")\
.replace("'", '"')
# Replace object and function repr's like <MyObject ...>
string_repr = re.sub(r':(\s+)(<[^>]+>)', r':\1"\2"', string_repr)
# Replace tuples with lists, very naively
string_repr = string_repr.replace('(', '[').replace(')', ']')
info = json.dumps(json.loads(string_repr), **kwargs)
except:
from pprint import pformat
info = pformat(value, indent=2)
def _out(formatted_string, *format_args):
"""Format the string and output it to the correct location."""
if stdout:
print(formatted_string % format_args)
else:
logging.debug(formatted_string, *format_args)
if max_length is None or len(info) <= max_length:
_out('%s: %s', msg, info)
return True
else:
_out(
'Did not dump "%s" due to length restriction. Increase max_length if desired.', msg
)
return False
except:
,那样会捕获系统异常。 - Falmarri