How to recursively enrich json object with custom field using python jsons

Question

I'm using jsons library and would like to add a custom serializer that for a given type adds a certain field.

Naive example:

def adjust(obj):
    if isinstance(obj, MyFoo):
        json = jsons.dump(obj)
        json['foo'] = "bar"
        return json
jsons.set_serializer(lambda obj, **_: adjust(obj), MyFoo)
json = jsons.dump(data, ensure_ascii=True)

This doesn't work because it goes into infinite recursion. I tried playing with forks but couldn't make it work.

What is important, MyFoo might appear inside other MyFoos and so the serializer must work on all levels.

Out of more than 50 existing questions tagged [tag:python-jsons], this was the **only one** that was actually about the `jsons` library, which is what the tag is presumably intended for. I retagged all the others. — Karl Knechtel, Apr 01 '23 at 08:15

score 0 · Answer 1 · answered Mar 22 '23 at 06:01

I managed to solve it. The trick was to use jsons.default_object_serializer

def adjust(obj):
    if isinstance(obj, MyFoo):
        json = jsons.default_object_serializer(obj)
        json['foo'] = "bar"
        return json
jsons.set_serializer(lambda obj, **_: adjust(obj), MyFoo)
json = jsons.dump(data, ensure_ascii=True)

How to recursively enrich json object with custom field using python jsons

1 Answers1