JSON

Reading and writing JSON files

The json module allows reading and writing JSON files using json.load() and json.dump().

JSON objects are mapped to dict, while JSON arrays are converted into list. Other native types, such as strings, integers, floats, and booleans, are also directly supported.

Example writing a dict to a JSON file:

import json

data = {'name': 'Daniel', 'age': 24}
with open('data.json', 'w') as file:
    json.dump(data, file)

Example reading a JSON file into a dict:

with open('data.json', 'r') as file:
    loaded_data = json.load(file)
print(loaded_data)

Output:

{'name': 'Daniel', 'age': 24}

Parsing JSON data

To parse a JSON string into a Python object, use json.loads().

Example:

json_string = '{"name": "Daniel", "age": 24}'
parsed_data = json.loads(json_string)
print(parsed_data['name'])

Output:

Daniel

Handling complex data structures in JSON

For custom objects, define a function for serialization.

Example:

class City:
    def __init__(self, name, temperature):
        self.name = name
        self.temperature = temperature

def city_to_dict(city):
    return {'name': city.name, 'temperature': city.temperature}

city = City('Madrid', 45)
json_data = json.dumps(city, default=city_to_dict)
print(json_data)

Output:

{'name': 'Madrid', 'temperature': 45}

Last modified: 17 March 2025