Response object creation in Flask - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Flask response code?

Consider this Flask route code. What will the client receive as the response body?

Flask

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

@app.route('/')
def home():
    return Response('Hello World', status=200, mimetype='text/plain')

A A JSON response with body 'Hello World' and status 200

B A plain text response with body 'Hello World' and status 200

C An HTML response with body 'Hello World' and status 404

D A plain text response with empty body and status 200

💡 Hint

Check the mimetype and status parameters in the Response constructor.

The Response object is created with the string 'Hello World', status 200, and mimetype 'text/plain'. This means the client receives plain text with that exact body and status code.

📝 Syntax

intermediate

Which option correctly creates a JSON response in Flask?

You want to return a JSON response with data {'success': True} and status 201. Which code snippet is correct?

A return Response(json.dumps({'success': True}), status=201, mimetype='application/json')

B return Response(json.dumps({'success': True}), status=201)

C return Response({'success': True}, status=201)

D return Response({'success': True}, status=201, mimetype='application/json')

💡 Hint

Remember that Response expects a string or bytes for the body, not a dict.

Option A correctly converts the dictionary to a JSON string using json.dumps and sets the mimetype to 'application/json'. Option A passes a dict directly causing a TypeError. Option A misses mimetype and passes dict. Option A passes JSON string but misses mimetype, so content type is default.

🔧 Debug

advanced

Why does this Flask response raise a TypeError?

Examine the code below. Why does it raise a TypeError when the route is accessed?

Flask

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

@app.route('/data')
def data():
    return Response({'key': 'value'}, status=200, mimetype='application/json')

A The mimetype 'application/json' is invalid and causes TypeError

B Status code 200 is not allowed with Response and causes TypeError

C Response body must be a string or bytes, not a dict, causing TypeError

D Flask requires jsonify() to create any Response, else TypeError occurs

💡 Hint

Check the type of the first argument passed to Response.

Response expects the body to be a string or bytes. Passing a dict directly causes a TypeError because Flask cannot convert it automatically.

❓ state_output

advanced

What is the status code of this Flask response?

Given this Flask route, what status code will the client receive?

Flask

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

@app.route('/custom')
def custom():
    resp = Response('Done')
    resp.status_code = 202
    return resp

A 202

B 500

C 200

D None

💡 Hint

Look at how the status_code attribute is set before returning the response.

The Response object is created with default status 200, but then status_code is changed to 202 before returning. So the client receives status 202.

🧠 Conceptual

expert

Which statement about Flask Response objects is true?

Select the one true statement about creating Response objects in Flask.

A Setting the status code after returning the Response object changes the response sent to client.

B Response objects can be created with any data type as body; Flask converts it automatically.

C You must always use Flask's jsonify() to create a Response; Response() cannot handle JSON strings.

D Response objects require the body to be bytes or string; passing other types causes errors.

💡 Hint

Think about what types Response accepts for its body parameter.

Flask Response expects the body to be a string or bytes. Passing other types like dict causes errors. jsonify() is a helper but not mandatory. Status code must be set before returning the Response object.