Accessing JSON data in Flask - Cheat Sheet & Quick Revision

Recall & Review

beginner

What Flask method do you use to get JSON data sent in a POST request?

You use request.get_json() to access JSON data sent in a POST request in Flask.

beginner

How do you import the object needed to access JSON data in Flask?

You import <code>request</code> from <code>flask</code> like this: <code>from flask import request</code>.

beginner

What type of data does request.get_json() return?

It returns a Python dictionary representing the JSON data sent by the client.

intermediate

What happens if the incoming request does not contain valid JSON and you call request.get_json()?

By default, it returns None if the JSON is missing or invalid.

intermediate

How can you safely access a key from JSON data in Flask to avoid errors if the key is missing?

Use the dictionary .get() method on the JSON data, like data.get('key'), which returns None if the key is missing.

Which Flask object do you use to access JSON data sent by a client?

A request

B response

C jsonify

D session

The request object holds data sent by the client, including JSON.

What does request.get_json() return if the request has no JSON data?

A An error is raised

B An empty dictionary {}

C None

D A string with raw data

By default, request.get_json() returns None if no JSON is present.

How do you import the request object in Flask?

A import request

B import flask.request

C from flask.request import *

D from flask import request

You import request from the flask module using from flask import request.

If you want to safely get a value from JSON data without risking a KeyError, what should you do?

A Use data['key']

B Use data.get('key')

C Use data.key

D Use data.fetch('key')

Using data.get('key') returns None if the key is missing, avoiding errors.

Which HTTP method usually carries JSON data that you want to access with request.get_json()?

A POST

B HEAD

C DELETE

D GET

JSON data is commonly sent in the body of POST requests.

Explain how to access JSON data sent by a client in a Flask route.

Think about the Flask object that holds request data and the method to parse JSON.

Describe what happens if you call request.get_json() but the client sends no JSON data.

Consider the default behavior of get_json when JSON is missing.