Python JSON Operations

This post will demonstrate how to work with json data in python. The full python documentation can be found here.

Basic Operations

Reading JSON Data

To retrieve data written to a json file:

def getJsonData(fileName: str):
    inputFile = open(fileName, 'r')
    jsonData = json.loads(inputFile.read())
    inputFile.close()

    return jsonData

This returns a dict made up of the json data.

Writing JSON Data

To transform a dict into a json string, then write it to an output file:

def writeJsonToFile(outputData: dict, fileName: str) -> None:
    jsonString = json.dumps(outputData, sort_keys=True, indent=4)

    with open(fileName, "w") as outputFile:
        outputFile.write(jsonString)

Transforming an object to a json string

If you try to write an object to json using the method above, you will get an error. To fix this, just add a simple part to writeJsonToFile():

def writeJsonToFile(outputData: dict, fileName: str) -> None:
    jsonString = json.dumps(object, indent=4, sort_keys=True, default=lambda o: getattr(o, '__dict__', str(o)))

    with open(fileName, "w") as outputFile:
        outputFile.write(jsonString)