HTTP methods (GET, POST, PUT, DELETE) in Flask - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Flask route when accessed with a GET request?

Consider this Flask route:

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

@app.route('/data', methods=['GET', 'POST'])
def data():
    if request.method == 'POST':
        return 'Posted Data'
    else:
        return 'Got Data'

What will the server respond with when a GET request is sent to /data?

Flask

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

@app.route('/data', methods=['GET', 'POST'])
def data():
    if request.method == 'POST':
        return 'Posted Data'
    else:
        return 'Got Data'

A The response will be 'Posted Data'

B The response will be 'Got Data'

C The server will return a 405 Method Not Allowed error

D The server will return a 404 Not Found error

💡 Hint

Think about which method triggers which return statement.

The route accepts both GET and POST. When the method is GET, the else branch runs, returning 'Got Data'.

📝 Syntax

intermediate

Which Flask route definition correctly handles PUT requests?

Choose the correct Flask route decorator to handle PUT requests on the path /update.

A @app.route('/update', methods=['PUT'])

B @app.route('/update', methods='PUT')

C @app.route('/update', method='PUT')

D @app.route('/update', methods=['put'])

💡 Hint

Check the spelling and type of the methods argument.

The methods argument must be a list of uppercase HTTP method strings. Option A is correct.

🔧 Debug

advanced

What error does this Flask route raise when accessed with DELETE?

Given this Flask route:

@app.route('/item', methods=['GET', 'POST'])
def item():
    return 'Item endpoint'

What happens if a client sends a DELETE request to /item?

Flask

@app.route('/item', methods=['GET', 'POST'])
def item():
    return 'Item endpoint'

A The server returns a 404 Not Found error

B The server raises a TypeError

C The server returns 'Item endpoint'

D The server returns a 405 Method Not Allowed error

💡 Hint

Check which methods are allowed by the route.

The route only allows GET and POST. DELETE is not allowed, so Flask returns a 405 error.

❓ state_output

advanced

What is the final value of the list after these HTTP requests?

Consider this Flask app snippet:

from flask import Flask, request
app = Flask(__name__)
items = []

@app.route('/add', methods=['POST'])
def add():
    items.append(request.json.get('item'))
    return 'Added'

If the client sends these requests in order:

1. POST to /add with JSON {"item": "apple"}
2. POST to /add with JSON {"item": "banana"}
3. GET to /add

What is the value of items after these requests?

Flask

from flask import Flask, request
app = Flask(__name__)
items = []

@app.route('/add', methods=['POST'])
def add():
    items.append(request.json.get('item'))
    return 'Added'

A ['apple', 'banana']

B ['apple']

C []

D ['banana']

💡 Hint

Remember that GET requests to this route are not handled.

Both POST requests add items to the list. The GET request does nothing to the list because it is not handled.

🧠 Conceptual

expert

Which HTTP method is idempotent and safe according to REST principles?

In REST API design, which HTTP method is considered both idempotent and safe?

A PUT

B POST

C GET

D DELETE

💡 Hint

Safe means it does not change server state. Idempotent means multiple identical requests have the same effect as one.

GET requests do not change data (safe) and can be repeated without side effects (idempotent). POST is not idempotent or safe. PUT and DELETE are idempotent but not safe.