How to return a json object from a Python function?

Returning a JSON object from a Python function involves converting Python data (like dictionaries or lists) into a JSON-formatted string or response, depending on the use case. For example, if you're working with APIs, you might return a JSON response using frameworks like Flask. Let's explore several efficient methods to return a JSON object from a Python function.

Using json.dumps()

This is the most basic and widely-used way to convert a Python dictionary to a JSON string using Python’s built-in json module. It doesn't require any third-party packages or frameworks.

import json
def fun():
    d = {
        "language": "Python",
        "company": "GeeksForGeeks",
        "Itemid": 1,
        "price": 0.00
    }
    return json.dumps(d)
print(fun())

{"language": "Python", "company": "GeeksForGeeks", "Itemid": 1, "price": 0.0}

Explanation: fun() function creates a dictionary with details like language, company, item ID and price, then uses json.dumps() to convert it into a JSON string. print(fun()) calls the function and prints the JSON output to the console.

Using orjson

orjson is a high-performance JSON library for Python. It is faster and more efficient than the standard json module, especially when working with large data or requiring faster serialization.

import orjson
def fun():
    d = {
        "language": "Python",
        "company": "GeeksForGeeks",
        "Itemid": 1,
        "price": 0.00
    }
    return orjson.dumps(d).decode()
print(fun())

Output

{"language":"Python","company":"GeeksForGeeks","Itemid":1,"price":0.0}

Explanation: fun() function creates a dictionary with details like language, company, item ID and price, then uses orjson.dumps() to convert it into a JSON string. Since orjson returns bytes, .decode() is used to convert it to a string.

Using jsonify()

jsonify() is part of Flask and is used to create a proper HTTP JSON response. It is the best choice when you're building a web API or returning JSON data from a Flask route.

from flask import Flask, jsonify
app = Flask(__name__)

def fun():
    d = {"language": "Python"}
    return jsonify(d)

with app.app_context():
    response = fun()
    print(response.get_data(as_text=True))

Output

{"language":"Python"}

Explanation: fun() function creates a dictionary and uses jsonify() to convert it into a JSON response. Since jsonify() requires a Flask context, app.app_context() is used. The response is then printed using response.get_data(as_text=True).