Why middleware extends functionality in Flask - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add middleware that logs each request in Flask.

Flask

from flask import Flask, request

app = Flask(__name__)

@app.before_request
def [1]():
    print(f"Request to: {request.path}")

@app.route('/')
def home():
    return 'Hello!'

Drag options to blanks, or click blank then click option'

Ahandle_request

Bbefore_request

Clog_request

Dprocess_request

Attempts:

3 left

💡 Hint

Common Mistakes

Using a function name that doesn't describe its purpose

Not using the @app.before_request decorator

The function decorated with @app.before_request runs before each request. Naming it log_request makes its purpose clear.

2fill in blank

medium

Complete the code to create middleware that modifies the response headers.

Flask

from flask import Flask, Response

app = Flask(__name__)

@app.after_request
def add_header(response: Response):
    response.headers['X-Custom-Header'] = [1]
    return response

@app.route('/')
def home():
    return 'Hello!'

Drag options to blanks, or click blank then click option'

A'Middleware-Active'

B'Active-Middleware'

C'Custom-Header'

D'Header-Set'

Attempts:

3 left

💡 Hint

Common Mistakes

Using a header value that doesn't clearly indicate middleware

Forgetting to return the response object

The middleware adds a custom header with the value 'Middleware-Active' to the response headers.

3fill in blank

hard

Fix the error in the middleware function that blocks requests to '/secret'.

Flask

from flask import Flask, request, abort

app = Flask(__name__)

@app.before_request
def block_secret():
    if request.path == [1]:
        abort(403)

@app.route('/secret')
def secret():
    return 'Top secret!'

Drag options to blanks, or click blank then click option'

A'/secret'

B'secret/'

C'/Secret'

D'secret'

Attempts:

3 left

💡 Hint

Common Mistakes

Using a path without the leading slash

Using incorrect casing in the path string

The path must exactly match '/secret' to block access properly.

4fill in blank

hard

Fill both blanks to create middleware that measures request processing time and adds it to response headers.

Flask

import time
from flask import Flask, g, request

app = Flask(__name__)

@app.before_request
def start_timer():
    g.start = [1]

@app.after_request
def add_duration(response):
    duration = time.time() - g.start
    response.headers['X-Duration'] = str(duration) + [2]
    return response

Drag options to blanks, or click blank then click option'

Atime.time()

B' seconds'

C' ms'

Dtime.perf_counter()

Attempts:

3 left

💡 Hint

Common Mistakes

Using time.perf_counter() which is more precise but less common here

Forgetting to convert duration to string before concatenation

The middleware uses time.time() to record the start time and adds the duration in seconds as a string with ' seconds' suffix to the response header.

5fill in blank

hard

Fill all three blanks to create middleware that modifies request data and response data.

Flask

from flask import Flask, request, jsonify

app = Flask(__name__)

@app.before_request
def modify_request():
    if request.is_json:
        data = request.get_json()
        data[[1]] = [2]
        request.json = data

@app.after_request
def modify_response(response):
    if response.is_json:
        json_data = response.get_json()
        json_data[[3]] = 'modified by middleware'
        response.set_data(jsonify(json_data).get_data())
    return response

Drag options to blanks, or click blank then click option'

A'middleware_flag'

BTrue

C'middleware_status'

D'status'

Attempts:

3 left

💡 Hint

Common Mistakes

Using keys that don't match between request and response

Not updating the response data properly after modification

The middleware adds a 'middleware_flag' with value True to the request JSON, and adds 'middleware_status' to the response JSON to show it was modified.