Request object properties in Flask - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What does request.args contain in Flask?

Consider a Flask route that handles a URL like /search?query=flask&sort=asc. What does request.args represent?

Flask

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

@app.route('/search')
def search():
    return str(request.args)

A The raw bytes of the request body

B The JSON body of the request parsed as a dictionary

C The form data submitted via POST method

D A dictionary-like object containing the URL query parameters {'query': 'flask', 'sort': 'asc'}

💡 Hint

Think about what appears after the question mark in a URL.

request.args holds the query parameters from the URL as a dictionary-like object. It does not contain form data or JSON body.

❓ state_output

intermediate

What is the output of request.method for a POST request?

Given a Flask route that accepts both GET and POST, what will request.method return when the client sends a POST request?

Flask

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

@app.route('/submit', methods=['GET', 'POST'])
def submit():
    return request.method

A 'post'

B 'GET'

C 'POST'

D None

💡 Hint

HTTP methods are uppercase strings in Flask's request.method.

request.method returns the HTTP method used for the request as an uppercase string, so for POST requests it returns 'POST'.

📝 Syntax

advanced

Which option correctly accesses JSON data from a Flask request?

Assuming a client sends JSON data {"name": "Alice"} in a POST request, which code correctly extracts the value of name?

Flask

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

@app.route('/json', methods=['POST'])
def json_route():
    # Extract name from JSON here
    pass

A name = request.get_json()['name']

B name = request.json['name']

C name = request.data['name']

D name = request.form['name']

💡 Hint

Use the method that parses JSON safely from the request body.

request.get_json() parses the JSON body and returns a dictionary. request.json is a property but can be None if content type is wrong. request.data is raw bytes, and request.form is for form data.

🔧 Debug

advanced

Why does accessing request.form['username'] raise a KeyError?

A Flask route expects form data with a field username. The code request.form['username'] raises a KeyError. What is the most likely reason?

Flask

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

@app.route('/login', methods=['POST'])
def login():
    user = request.form['username']
    return f"Hello {user}"

A The client did not send form data with a 'username' field

B The request method is GET, so form data is empty

C request.form only works with JSON data

D Flask requires special headers to access form data

💡 Hint

Think about what happens if the expected form field is missing.

If the client does not send a form field named 'username', accessing it with request.form['username'] raises a KeyError. Using request.form.get('username') avoids this error.

🧠 Conceptual

expert

Which request property provides the raw bytes of the request body?

In Flask, you want to access the raw bytes sent in the request body regardless of content type. Which request property gives you this?

A request.args

B request.data

C request.form

D request.json

💡 Hint

Think about the raw content before parsing.

request.data contains the raw bytes of the request body. request.form is parsed form data, request.json is parsed JSON, and request.args is query parameters.