Easiest way to serialize a simple class object with simplejson?

Question

I\'m trying to serialize a list of python objects with JSON (using simplejson) and am getting the error that the object \"is not JSON serializable\".

The class is a

Answer 1

I have a similar problem but the json.dump function is not called by me. So, to make MyClass JSON serializable without giving a custom encoder to json.dump you have to Monkey patch the json encoder.

First create your encoder in your module my_module:

import json

class JSONEncoder(json.JSONEncoder):
    """To make MyClass JSON serializable you have to Monkey patch the json
    encoder with the following code:
    >>> import json
    >>> import my_module
    >>> json.JSONEncoder.default = my_module.JSONEncoder.default
    """
    def default(self, o):
        """For JSON serialization."""
        if isinstance(o, MyClass):
            return o.__repr__()
        else:
            return super(self,o)

class MyClass:
    def __repr__(self):
        return "my class representation"

Then as it is described in the comment, monkey patch the json encoder:

import json
import my_module
json.JSONEncoder.default = my_module.JSONEncoder.default

Now, even an call of json.dump in an external library (where you cannot change the cls parameter) will work for your my_module.MyClass objects.