Cache busting strategies in Flask - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a version query parameter for cache busting in a Flask template URL.

Flask

url_for('static', filename='style.css') + '?v=[1]'

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

Aversion

Bcache

Crandom

Dtimestamp

Attempts:

3 left

💡 Hint

Common Mistakes

Using a fixed string that never changes, so cache is not busted.

Forgetting to add the query parameter at all.

Using a timestamp as a query parameter helps browsers load the latest file version by changing the URL when the file updates.

2fill in blank

medium

Complete the Flask route to send a static file with a cache-busting header.

Flask

from flask import send_from_directory, make_response

@app.route('/static/<path:filename>')
def static_files(filename):
    response = make_response(send_from_directory('static', filename))
    response.headers['Cache-Control'] = '[1]'
    return response

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

Ano-cache, no-store, must-revalidate

Bmax-age=3600

Cpublic, max-age=86400

Dprivate, max-age=0

Attempts:

3 left

💡 Hint

Common Mistakes

Using a long max-age which allows caching.

Not setting Cache-Control header at all.

Setting 'no-cache, no-store, must-revalidate' tells browsers not to cache the file, ensuring fresh content.

3fill in blank

hard

Fix the error in the Flask template to append a file hash for cache busting.

Flask

<link rel="stylesheet" href="{{ url_for('static', filename='style.css') }}?v=[1]">

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

Ahash

Bhash_file

Cget_hash()

Dfile_hash

Attempts:

3 left

💡 Hint

Common Mistakes

Using a function call inside the template variable.

Using a variable name not passed from the view.

The variable 'hash' should be passed from the Flask view to the template to append the file's hash for cache busting.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps filenames to their cache-busted URLs using a version number.

Flask

cache_busted_urls = {file: url_for('static', filename=file) + '?v=' + [1] for file in files if file.[2]('.css')}

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

Aversion

Bendswith

Cstartswith

Din

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'startswith' instead of 'endswith' for file extension.

Not appending the version parameter.

The dictionary comprehension appends the version to URLs only for files ending with '.css'.

5fill in blank

hard

Fill all three blanks to create a Flask function that returns a static file URL with a timestamp cache buster and sets a no-cache header.

Flask

from flask import url_for, make_response, send_from_directory
import time

def get_static_file(filename):
    url = url_for('static', filename=filename) + '?v=' + str([1])
    response = make_response(send_from_directory('static', filename))
    response.headers['Cache-Control'] = '[2]'
    return response, url

current_time = [3]

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

Atime.time()

Bno-cache, no-store, must-revalidate

Cint(time.time())

Dmax-age=3600

Attempts:

3 left

💡 Hint

Common Mistakes

Using float timestamp which may cause URL issues.

Setting Cache-Control to allow caching.

The function uses the current integer timestamp for cache busting and sets headers to prevent caching.