JSON (JavaScript Object Notation) is a lightweight text format used to represent data. It’s widely used in REST APIs, configuration files, and databases such as MongoDB.

Running the script

Save the code into a file called json_example.py and run it with:

python json_example.py

JSON structure

JSON works with objects {} and arrays []. Values can be strings, numbers, booleans, null, objects, or arrays. Example:

[
  {
    "nombre_alumno": "Nil",
    "apellido1": "Medrano",
    "fecha_entrada": "2024-01-26",
    "completa": true,
    "notas": [10, 10, 10, 10, 9, 10, 10],
    "observaciones": "Sample observation 1"
  }
]

Reading JSON from a file

Using Python’s json module:

import json

with open("insert.json", "r", encoding="utf-8") as f:
    data = json.load(f)

for student in data:
    print(student["nombre_alumno"], student["notas"])

Writing JSON to a file

nuevo_dato = {"nombre": "Ana", "nota": 8}
data.append(nuevo_dato)

with open("salida.json", "w", encoding="utf-8") as f:
    json.dump(data, f, indent=2, ensure_ascii=False)

Converting strings to JSON and back

json.loads() converts a string into a dictionary/list. json.dumps() does the opposite. This is useful when you receive JSON over the network (for example, from an API).