How to extend json.JSONEncoder class? I want to encode other Python data types to JSON.

If you encode your own data types to JSON strings, you need to extend the json.JSONEncoder class and override the default() function.

The following Python example shows you how to extend json.JSONEncoder class to encode "complex" data type into JSON format:

C:\fyicenter>type MyJSONEncoder.py
# MyJSONEncoder.py
# Copyright (c) FYIcenter.com 

import json
class MyJSONEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, complex):
            return {'r': obj.real, 'i': obj.imag}
        return json.JSONEncoder.default(self, obj)

encoder = MyJSONEncoder(indent=4)
i = 2
f = 2.1
c = 2 + 1j
o = {'int': i, 'float': f, 'complex': c}
j = encoder.encode(o)
print(j)

C:\fyicenter>python MyJSONEncoder.py
{
    "int": 2,
    "float": 2.1,
    "complex": {
        "r": 2.0,
        "i": 1.0
    }
}

⇒ json.loads() - Loading JSON into Object

⇐ What Is json.JSONEncoder Class

⇑ 'json' Module - JSON Encoder and Decoder

⇑⇑ Python Tutorials