Request object properties in Flask - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to get the HTTP method of the request.

Flask

method = request.[1]

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

Amethod_method

Bmethod_type

Cmethod_name

Dmethod

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-existent property like request.method_type

Trying to call request.method as a function

The request.method property returns the HTTP method used (GET, POST, etc.).

2fill in blank

medium

Complete the code to access the query parameters from the request.

Flask

args = request.[1]

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

Aform

Bargs

Cjson

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Using request.form which is for POST form data

Using request.json which is for JSON body data

The request.args property contains the URL query parameters as a dictionary-like object.

3fill in blank

hard

Fix the error in accessing JSON data from the request.

Flask

data = request.[1]()

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

Aget_json

Bjsonify

Cjson_data

Djson

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to access request.json as a method

Using request.json_data which does not exist

The correct method to parse JSON body data is request.get_json().

4fill in blank

hard

Fill both blanks to get a form value safely with a default.

Flask

username = request.[1].get('[2]', 'guest')

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

Aform

Bargs

Cemail

Dusername

Attempts:

3 left

💡 Hint

Common Mistakes

Using request.args for form data

Using wrong key names that don't match the form field

Use request.form.get('username', 'guest') to get the form field 'username' with a default value.

5fill in blank

hard

Fill all three blanks to check if the request method is POST and get JSON data.

Flask

if request.[1] == '[2]':
    data = request.[3]()

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

Amethod

BPOST

Cget_json

Dargs

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing method to lowercase 'post'

Using request.json as a method instead of get_json()

Check request.method == 'POST' and then get JSON data with request.get_json().

Practice

1. What does request.method in Flask represent?

easy

A. The client's IP address

B. The URL path requested by the client

C. The response status code

D. The HTTP method used by the client (GET, POST, etc.)

Solution

1. Step 1: Understand the role of request.method

   This property tells you which HTTP method the client used to send the request, such as GET or POST.

2. Step 2: Differentiate from other request properties

   It is not the URL path, IP address, or response code, which are accessed differently.

3. Final Answer:

   The HTTP method used by the client (GET, POST, etc.) -> Option D

4. Quick Check:

   request.method = HTTP method [OK]

Hint: Remember: method means GET, POST, PUT, DELETE [OK]

Common Mistakes:

• Confusing method with URL or path
• Thinking method is client IP
• Mixing method with response status

2. Which of the following is the correct way to access query parameters from a Flask request object?

easy

A. request.args.get('param')

B. request.form['param']

C. request.cookies['param']

D. request.headers['param']

Solution

1. Step 1: Identify how query parameters are accessed

   Query parameters are part of the URL after the question mark and are accessed via request.args.

2. Step 2: Use the correct method to get a parameter

   Using request.args.get('param') safely retrieves the value or returns None if missing.

3. Final Answer:

   request.args.get('param') -> Option A

4. Quick Check:

   Query params = request.args.get() [OK]

Hint: Query params use request.args.get('name') [OK]

Common Mistakes:

• Using request.form for query parameters
• Trying to get query params from cookies or headers
• Using request.args['param'] without .get() risking KeyError

3. Given this Flask route code snippet, what will be printed if a client sends a POST request with form data {'username': 'alice'}?

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

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

medium

A. User: alice, Method: POST

B. User: None, Method: GET

C. User: alice, Method: GET

D. User: None, Method: POST

Solution

1. Step 1: Understand the request method and form data

   The client sends a POST request with form data containing 'username' = 'alice'.

2. Step 2: Check how data is accessed in the code

   The code uses request.form.get('username') which retrieves 'alice', and request.method which is 'POST'.

3. Final Answer:

   User: alice, Method: POST -> Option A

4. Quick Check:

   Form data and method match output [OK]

Hint: Form data is in request.form; method is request.method [OK]

Common Mistakes:

• Assuming method is GET when POST was sent
• Using request.args instead of request.form for POST data
• Expecting None for existing form data

4. What is wrong with this Flask code snippet if it raises a KeyError when accessing request.form['email']?

@app.route('/submit', methods=['POST'])
def submit():
    email = request.form['email']
    return f"Email: {email}"

medium

A. Flask requires request.args for form data

B. The route should accept GET method instead of POST

C. The form data might not include 'email', causing KeyError

D. request.form cannot be accessed directly

Solution

1. Step 1: Understand why KeyError occurs

   Accessing request.form['email'] raises KeyError if 'email' is missing in the form data.

2. Step 2: Suggest safer access method

   Use request.form.get('email') to avoid KeyError and get None if missing.

3. Final Answer:

   The form data might not include 'email', causing KeyError -> Option C

4. Quick Check:

   Missing key in form causes KeyError [OK]

Hint: Use .get() to avoid KeyError on missing form keys [OK]

Common Mistakes:

• Assuming form always has the key
• Confusing form data with query parameters
• Thinking request.form is inaccessible

5. You want to check if a client sent a cookie named session_id in a Flask route. Which code snippet correctly checks for it and returns its value or 'No session' if missing? A)

sid = request.cookies['session_id']
return sid if sid else 'No session'

B)

sid = request.cookies.get('session_id')
return sid or 'No session'

C)

sid = request.form.get('session_id')
return sid or 'No session'

D)

sid = request.args.get('session_id')
return sid or 'No session'

hard

A. Access cookie directly with [] and check truthiness

B. Use .get() on cookies and return fallback if missing

C. Check form data for cookie value

D. Check query parameters for cookie value

Solution

1. Step 1: Identify how to safely access cookies

   Cookies are accessed via request.cookies. Using .get() avoids KeyError if cookie is missing.

2. Step 2: Return cookie value or fallback

   Using sid or 'No session' returns the cookie value if present, else the fallback string.

3. Final Answer:

   Use .get() on cookies and return fallback if missing -> Option B

4. Quick Check:

   Cookies use request.cookies.get() safely [OK]

Hint: Use request.cookies.get('name') to avoid errors [OK]

Common Mistakes:

• Accessing cookies with [] risking KeyError
• Looking for cookies in form or args
• Not providing fallback for missing cookie