python使用属性将自定义对象转换为json

Question

In Bottle framework or python in general, is there a way to convert a custom object to json using the properties of the object? I saw few posts which recommend to write to_json(self) kind sort of method on the custom class. Was wondering if there is any automated way of doing the same?

Coming from Java world, was hoping for Jackson type of module with XmlRootElement annotation (or decorator in python terms). But didn't find any so far.

UPDATE I do not want to use __dict__ elements. Instead want to use properties of my custom class to build the json.

Answer 1

You could use a decorator to "mark" the properties that needs to be represented. You would still need to write a to_json function, but you will only need to define it once in the base class

Here's a simple example:

import json
import inspect

def viewable(fnc):
        '''
            Decorator, mark a function as viewable and gather some metadata in the process

        '''
        def call(*pargs, **kwargs):
                return fnc(*pargs, **kwargs)
        # Mark the function as viewable
        call.is_viewable = True
        return call

class BaseJsonable(object):

    def to_json(self):
        result = {}
        for name, member in inspect.getmembers(self):
            if getattr(member, 'is_viewable', False):
                value = member()
                result[name] = getattr(value, 'to_json', value.__str__)()
        return json.dumps(result)

class Person(BaseJsonable):

    @viewable
    def name(self):
        return self._name


    @viewable
    def surname(self):
        return self._surname

    def __init__(self, name, surname):
        self._name = name
        self._surname = surname


p = Person('hello', 'world')
print p.to_json()

Prints

{"surname": "world", "name": "hello"}