Redirect and abort functions in Flask - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the function that sends users to a different page.

Flask

from flask import [1]

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

Arender_template

Babort

Credirect

Drequest

Attempts:

3 left

💡 Hint

Common Mistakes

Importing 'abort' instead of 'redirect'.

Confusing 'render_template' with 'redirect'.

The redirect function is used to send users to a different URL in Flask.

2fill in blank

medium

Complete the code to stop the request and return a 404 error.

Flask

from flask import [1]

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

Aabort

Bredirect

Curl_for

Dflash

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'redirect' to handle errors.

Trying to return error codes manually without 'abort'.

The abort function stops the request and returns an HTTP error code like 404.

3fill in blank

hard

Fix the error in this code that tries to redirect to the home page.

Flask

return [1]('/')

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

Aabort

Bredirect

Crender_template

Durl_for

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'abort' instead of 'redirect'.

Using 'render_template' which only renders a page without redirecting.

The redirect function is used to send the user to a different URL, like the home page.

4fill in blank

hard

Fill both blanks to abort with a 403 Forbidden error and a custom message.

Flask

return [1]([2], description='Access denied')

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

Aabort

Bredirect

C403

D404

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'redirect' instead of 'abort'.

Using the wrong error code like 404.

Use abort with the error code 403 to stop the request and show 'Forbidden'.

5fill in blank

hard

Fill all three blanks to redirect to the 'login' page using url_for inside redirect.

Flask

return [1]([2]('[3]'))

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

Aredirect

Burl_for

Clogin

Dabort

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'abort' instead of 'redirect'.

Not using 'url_for' to build the URL.

Use redirect with url_for to send users to the 'login' page.

Practice

1. What does the redirect function do in a Flask application?

easy

A. Sends the user to a different URL

B. Stops the request and shows an error code

C. Returns a JSON response

D. Renders an HTML template

Solution

1. Step 1: Understand the purpose of redirect

   The redirect function is used to send the user to a different URL in the browser.

2. Step 2: Compare with other functions

   Unlike abort which stops the request with an error, redirect changes the page location.

3. Final Answer:

   Sends the user to a different URL -> Option A

4. Quick Check:

   redirect = Send user to new URL [OK]

Hint: Redirect sends users to new pages, abort shows errors [OK]

Common Mistakes:

• Confusing redirect with abort
• Thinking redirect stops the request
• Assuming redirect returns HTML directly

2. Which of the following is the correct way to import and use abort in Flask?

easy

A. import flask.abort; abort(404)

B. import abort from flask; abort(404)

C. from flask import abort; abort['404']

D. from flask import abort; abort(404)

Solution

1. Step 1: Check correct import syntax

   In Flask, functions like abort are imported using from flask import abort.

2. Step 2: Check correct usage

   The abort function is called with parentheses and an integer status code, e.g., abort(404).

3. Final Answer:

   from flask import abort; abort(404) -> Option D

4. Quick Check:

   Correct import and call syntax = from flask import abort; abort(404) [OK]

Hint: Use 'from flask import abort' and call abort(code) [OK]

Common Mistakes:

• Using wrong import syntax
• Calling abort with brackets instead of parentheses
• Trying to import abort with 'import abort from flask'

3. What will be the output when this Flask route is accessed?

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

@app.route('/')
def home():
    return redirect('/welcome')

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

medium

A. Shows a 404 error

B. Displays 'Hello, welcome!' in the browser

C. Returns a JSON response with 'Hello, welcome!'

D. Causes a server crash

Solution

1. Step 1: Analyze the '/' route

   The '/' route calls redirect('/welcome'), sending the browser to '/welcome'.

2. Step 2: Analyze the '/welcome' route

   The '/welcome' route returns the string 'Hello, welcome!'. So the browser shows this text.

3. Final Answer:

   Displays 'Hello, welcome!' in the browser -> Option B

4. Quick Check:

   Redirect leads to '/welcome' which returns greeting [OK]

Hint: Redirect sends user to new route which returns the message [OK]

Common Mistakes:

• Thinking redirect returns text directly
• Expecting JSON instead of plain text
• Assuming redirect causes error or crash

4. Identify the error in this Flask code snippet:

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

@app.route('/secret')
def secret():
    abort(403)
    return 'You should not see this'

medium

A. The return statement after abort is unreachable

B. abort must be called with a string, not a number

C. abort cannot be used inside route functions

D. Missing parentheses in abort call

Solution

1. Step 1: Understand abort behavior

   The abort(403) immediately stops the request and sends a 403 error response.

2. Step 2: Check code after abort

   The return statement after abort is never reached, so it is unreachable code.

3. Final Answer:

   The return statement after abort is unreachable -> Option A

4. Quick Check:

   Code after abort is ignored [OK]

Hint: Code after abort() won't run; it's unreachable [OK]

Common Mistakes:

• Thinking abort needs string argument
• Believing abort can't be used in routes
• Forgetting abort stops execution immediately

5. You want to redirect users to a login page if they are not authenticated, otherwise show their dashboard. Which Flask code snippet correctly uses redirect and abort to handle this?

hard

A. if not user_authenticated:
abort(401)
else:
return redirect('/dashboard')

B. if user_authenticated:
return redirect('/login')
else:
abort(200)

C. if not user_authenticated:
return redirect('/login')
else:
return 'Welcome to your dashboard!'

D. if user_authenticated:
abort(404)
else:
return redirect('/login')

Solution

1. Step 1: Understand user authentication logic

   If the user is not authenticated, they should be sent to the login page using redirect('/login').

2. Step 2: Handle authenticated users

   If authenticated, show the dashboard message directly with a return string.

3. Step 3: Check abort usage

   Using abort for normal redirects or success codes is incorrect; abort is for errors.

4. Final Answer:

   if not user_authenticated: return redirect('/login') else: return 'Welcome to your dashboard!' -> Option C

5. Quick Check:

   Redirect unauthenticated, show dashboard if authenticated [OK]

Hint: Redirect unauthenticated users, return dashboard text if authenticated [OK]

Common Mistakes:

• Using abort for normal redirects
• Aborting with success codes like 200
• Redirecting authenticated users to login