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
下面是一个简单功能的简单解决方案:
.toJSON()方法
实现一个序列化器方法,而不是一个JSON可序列化类:
import json
class Object:
def toJSON(self):
return json.dumps(self, default=lambda o: o.__dict__,
sort_keys=True, indent=4)
所以你只需调用它来序列化:
me = Object()
me.name = "Onur"
me.age = 35
me.dog = Object()
me.dog.name = "Apollo"
print(me.toJSON())
将输出:
{
"age": 35,
"dog": {
"name": "Apollo"
},
"name": "Onur"
}
另一种选择是将JSON转储打包到它自己的类中:
import json
class FileItem:
def __init__(self, fname):
self.fname = fname
def __repr__(self):
return json.dumps(self.__dict__)
或者,更好的是,从JsonSerializable类继承FileItem类:
import json
class JsonSerializable(object):
def toJson(self):
return json.dumps(self.__dict__)
def __repr__(self):
return self.toJson()
class FileItem(JsonSerializable):
def __init__(self, fname):
self.fname = fname
测试:
>>> f = FileItem('/foo/bar')
>>> f.toJson()
'{"fname": "/foo/bar"}'
>>> f
'{"fname": "/foo/bar"}'
>>> str(f) # string coercion
'{"fname": "/foo/bar"}'
import json
class Foo(object):
def __init__(self):
self.bar = 'baz'
self._qux = 'flub'
def somemethod(self):
pass
def default(instance):
return {k: v
for k, v in vars(instance).items()
if not str(k).startswith('_')}
json_foo = json.dumps(Foo(), default=default)
assert '{"bar": "baz"}' == json_foo
print(json_foo)
要添加另一个选项:您可以使用attrs包和asdict方法。
class ObjectEncoder(JSONEncoder):
def default(self, o):
return attr.asdict(o)
json.dumps(objects, cls=ObjectEncoder)
然后再转换回去
def from_json(o):
if '_obj_name' in o:
type_ = o['_obj_name']
del o['_obj_name']
return globals()[type_](**o)
else:
return o
data = JSONDecoder(object_hook=from_json).decode(data)
类看起来像这样
@attr.s
class Foo(object):
x = attr.ib()
_obj_name = attr.ib(init=False, default='Foo')
首先,我们需要使我们的对象符合JSON,这样我们就可以使用标准JSON模块转储它。我是这样做的:
def serialize(o):
if isinstance(o, dict):
return {k:serialize(v) for k,v in o.items()}
if isinstance(o, list):
return [serialize(e) for e in o]
if isinstance(o, bytes):
return o.decode("utf-8")
return o