python 2.7：TypeError：<__ main __。nested_object对象位于0x…>不能序列化JSON

Question

I'm trying to run the json.dumps method on a nested class/object and it fails on TypeError: <__main__.nested_object object at 0x...> is not JSON serializable

What should I change in my class so I could call json.dumps method with input parameters of an implementation of JSONEncoder?

Here is a very simple code that simulate the problem:

class leaf_object(object):
    def __init__(self, s):
        self.value = s

class nested_object(object):
    def __init__(self, a, b_list):
        self.a = a
        self.b_list = b_list

if __name__ == "__main__":
    obj = nested_object('a1', [leaf_object('a1.1'),leaf_object('a1.2')])
    import json
    print(json.dumps(obj))

Answer 1

You can use subclass JSONEncoder and implement your own custom serialization.so use this code :

from json import JSONEncoder

class leaf_object(object):
    def __init__(self, s):
        self.value = s

class nested_object(object):
    def __init__(self, a, b_list):
        self.a = a
        self.b_list = b_list

class MyEncoder(JSONEncoder):
    def default(self, o):
        return o.__dict__
if __name__ == "__main__":
    obj = nested_object('a1', [leaf_object('a1.1'),leaf_object('a1.2')])
    obj=MyEncoder().encode(obj)
    import json
    print(json.dumps(obj))

this is the result:

"{\"a\": \"a1\", \"b_list\": [{\"value\": \"a1.1\"}, {\"value\": \"a1.2\"}]}"