如何使一个Python类序列化?
class FileItem:
def __init__(self, fname):
self.fname = fname
尝试序列化为JSON:
>>> import json
>>> x = FileItem('/foo/bar')
>>> json.dumps(x)
TypeError: Object of type 'FileItem' is not JSON serializable
如何使一个Python类序列化?
class FileItem:
def __init__(self, fname):
self.fname = fname
尝试序列化为JSON:
>>> import json
>>> x = FileItem('/foo/bar')
>>> json.dumps(x)
TypeError: Object of type 'FileItem' is not JSON serializable
当前回答
这是我的3美分… 这演示了一个树状python对象的显式json序列化。 注意:如果你真的想要这样的代码,你可以使用twisted FilePath类。
import json, sys, os
class File:
def __init__(self, path):
self.path = path
def isdir(self):
return os.path.isdir(self.path)
def isfile(self):
return os.path.isfile(self.path)
def children(self):
return [File(os.path.join(self.path, f))
for f in os.listdir(self.path)]
def getsize(self):
return os.path.getsize(self.path)
def getModificationTime(self):
return os.path.getmtime(self.path)
def _default(o):
d = {}
d['path'] = o.path
d['isFile'] = o.isfile()
d['isDir'] = o.isdir()
d['mtime'] = int(o.getModificationTime())
d['size'] = o.getsize() if o.isfile() else 0
if o.isdir(): d['children'] = o.children()
return d
folder = os.path.abspath('.')
json.dump(File(folder), sys.stdout, default=_default)
其他回答
我喜欢Onur的答案,但会扩展到包括一个可选的toJSON()方法,用于对象序列化自己:
def dumper(obj):
try:
return obj.toJSON()
except:
return obj.__dict__
print json.dumps(some_big_object, default=dumper, indent=2)
我最喜欢Lost Koder的方法。当我试图序列化成员/方法不可序列化的更复杂的对象时,我遇到了问题。这是我的实现,工作在更多的对象:
class Serializer(object):
@staticmethod
def serialize(obj):
def check(o):
for k, v in o.__dict__.items():
try:
_ = json.dumps(v)
o.__dict__[k] = v
except TypeError:
o.__dict__[k] = str(v)
return o
return json.dumps(check(obj).__dict__, indent=2)
基于Quinten Cabo的回答:
def sterilize(obj):
"""Make an object more ameniable to dumping as json
"""
if type(obj) in (str, float, int, bool, type(None)):
return obj
elif isinstance(obj, dict):
return {k: sterilize(v) for k, v in obj.items()}
list_ret = []
dict_ret = {}
for a in dir(obj):
if a == '__iter__' and callable(obj.__iter__):
list_ret.extend([sterilize(v) for v in obj])
elif a == '__dict__':
dict_ret.update({k: sterilize(v) for k, v in obj.__dict__.items() if k not in ['__module__', '__dict__', '__weakref__', '__doc__']})
elif a not in ['__doc__', '__module__']:
aval = getattr(obj, a)
if type(aval) in (str, float, int, bool, type(None)):
dict_ret[a] = aval
elif a != '__class__' and a != '__objclass__' and isinstance(aval, type):
dict_ret[a] = sterilize(aval)
if len(list_ret) == 0:
if len(dict_ret) == 0:
return repr(obj)
return dict_ret
else:
if len(dict_ret) == 0:
return list_ret
return (list_ret, dict_ret)
区别在于
Works for any iterable instead of just list and tuple (it works for NumPy arrays, etc.) Works for dynamic types (ones that contain a __dict__). Includes native types float and None so they don't get converted to string. Classes that have __dict__ and members will mostly work (if the __dict__ and member names collide, you will only get one - likely the member) Classes that are lists and have members will look like a tuple of the list and a dictionary Python3 (that isinstance() call may be the only thing that needs changing)
如果你正在使用Python3.5+,你可以使用jsons。(PyPi: https://pypi.org/project/jsons/)它将把你的对象(及其所有属性递归地)转换为字典。
import jsons
a_dict = jsons.dump(your_object)
或者如果你想要一个字符串:
a_str = jsons.dumps(your_object)
或者你的类实现了jsons。JsonSerializable:
a_dict = your_object.json
正如在许多其他答案中提到的,您可以将函数传递给json。转储将不是默认支持的类型之一的对象转换为受支持的类型。令人惊讶的是,他们都没有提到最简单的情况,即使用内置函数vars将对象转换为包含其所有属性的dict:
json.dumps(obj, default=vars)
注意,这只涵盖了基本的情况,如果你需要对某些类型进行更具体的序列化(例如排除某些属性或没有__dict__属性的对象),你需要使用自定义函数或JSONEncoder,如其他答案中所述。