Custom status codes in Flask - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the HTTP status code returned by this Flask route?

Consider this Flask route that returns a custom status code.

What status code will the client receive when accessing this route?

Flask

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

@app.route('/custom')
def custom_status():
    return jsonify(message='Hello'), 202

# Assume app is running and /custom is accessed

A 202

B 404

C 200

D 500

💡 Hint

Look at the second value returned by the route function.

The route returns a tuple with the JSON response and the status code 202, so the client receives HTTP 202 Accepted.

📝 Syntax

intermediate

Which option correctly sets a custom status code in Flask?

You want to return a JSON response with a custom status code 418.
Which code snippet correctly does this?

A return jsonify(error='I am a teapot'), status=418

B return jsonify(error='I am a teapot', status=418)

C return jsonify(error='I am a teapot'), 418

D return jsonify(error='I am a teapot').status_code = 418

💡 Hint

Flask routes can return a tuple with response and status code.

Option C returns a tuple (response, status_code) which Flask understands. Other options either misuse parameters or syntax.

🔧 Debug

advanced

Why does this Flask route always return status 200 instead of 404?

Examine the code below:

```python @app.route('/item/') def get_item(id): item = find_item(id) if not item: return {'error': 'Not found'}, 404 return item ```
Despite returning 404 in the code, the client always receives 200. Why?

A The function returns a dict directly which Flask converts to 200, ignoring the tuple in the if block.

B The find_item function always returns a valid item, so 404 is never reached.

C Flask requires Response objects, not dicts, to set status codes.

D The route decorator is missing a methods argument, causing default 200.

💡 Hint

Check what the return type is in each branch.

Returning a dict directly sets status 200. The 404 tuple is only returned if item is None. If item is a dict, Flask returns 200 by default.

❓ state_output

advanced

What is the response status code after calling this Flask route twice?

Given this Flask app snippet:

```python from flask import Flask, jsonify app = Flask(__name__) counter = 0 @app.route('/count') def count(): global counter counter += 1 if counter > 1: return jsonify(message='Too many requests'), 429 return jsonify(message='First request'), 200 ```
What status code does the client receive on the second call to /count?

A 200

B 429

C 500

D 404

💡 Hint

Look at how the counter variable changes with each call.

On the first call, counter is 1, so status 200 is returned. On the second call, counter is 2, triggering status 429.

🧠 Conceptual

expert

Which statement about custom HTTP status codes in Flask is true?

Select the correct statement about using custom HTTP status codes in Flask responses.

A Flask automatically converts unknown status codes to 200 OK.

B Flask only supports standard HTTP status codes; custom codes cause errors.

C Custom status codes must be registered in Flask before use or they will raise exceptions.

D You can return any integer as a status code, but some clients may not recognize non-standard codes.

💡 Hint

Think about HTTP protocol and client behavior.

Flask allows any integer as status code, but clients may not handle unknown codes properly. Flask does not restrict codes or require registration.