如何使Python类可序列化?
How to make a Python class serializable?
一个简单的类:
class FileItem: def __init__(self, fname): self.fname = fname我应该怎么做才能获得以下输出:
What should I do to be able to get output of:
>>> import json >>> my_file = FileItem('/foo/bar') >>> json.dumps(my_file) TypeError: Object of type 'FileItem' is not JSON serializable没有错误
推荐答案您对预期的输出有想法吗?例如这样可以吗?
Do you have an idea about the expected output? For e.g. will this do?
>>> f = FileItem("/foo/bar") >>> magic(f) '{"fname": "/foo/bar"}'在这种情况下,您只能调用json.dumps(f.__dict__).
In that case you can merely call json.dumps(f.__dict__).
如果您想要更多的自定义输出,则必须子类化 ,并实现自己的自定义序列化.
If you want more customized output then you will have to subclass JSONEncoder and implement your own custom serialization.
有关一个简单的示例,请参见下文.
For a trivial example, see below.
>>> from json import JSONEncoder >>> class MyEncoder(JSONEncoder): def default(self, o): return o.__dict__ >>> MyEncoder().encode(f) '{"fname": "/foo/bar"}'然后将此类传递给 json.dumps() 方法为cls kwarg:
Then you pass this class into the json.dumps() method as cls kwarg:
json.dumps(cls=MyEncoder)如果您还想解码,则必须向object_hook rel ="noreferrer"> JSONDecoder 类.例如
If you also want to decode then you'll have to supply a custom object_hook to the JSONDecoder class. For e.g.
>>> def from_json(json_object): if 'fname' in json_object: return FileItem(json_object['fname']) >>> f = JSONDecoder(object_hook = from_json).decode('{"fname": "/foo/bar"}') >>> f <__main__.FileItem object at 0x9337fac> >>>更多推荐
如何使可序列化的JSON类
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