dynamo_json.py

import json


def _marshall(value):
    if isinstance(value, str):
        return {"S": value}
    elif isinstance(value, bool):
        return {"BOOL": value}
    elif isinstance(value, float) or isinstance(value, int):
        return {"N": str(value)}
    elif value is None:
        return {"NULL": True}
    elif isinstance(value, list):
        return {"L": [_marshall(v) for v in value]}
    elif isinstance(value, dict):
        return {"M": {k1: _marshall(v1) for k1, v1 in value.items()}}
    else:
        raise Exception("Don't know how to marshall type: " + str(type(value)))


def marshall(value):
    return {k: _marshall(v) for k, v in value.items()}


def _unmarshall(value):
    if "S" in value:
        return str(value["S"])
    elif "BOOL" in value:
        return value["BOOL"]
    elif "N" in value:
        return float(value["N"]) if ("." in value["N"] or "e" in value["N"]) else int(value["N"])
    elif "NULL" in value:
        return None
    elif "L" in value:
        return [_unmarshall(v) for v in value["L"]]
    elif "M" in value:
        return {k: _unmarshall(v) for k, v in value["M"].items()}
    else:
        raise Exception("No known data type descriptor found. Maybe this is already JSON?", value)


def unmarshall(value):
    return {k: _unmarshall(v) for k, v in value.items()}