API versioning with blueprints in Flask - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a Flask blueprint named 'v1'.

Flask

from flask import Blueprint

api_v1 = Blueprint('v1', __name__, url_prefix='/api/v1')

@api_v1.route('/hello')
def hello():
    return 'Hello from version 1!'

app.register_blueprint([1])

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

Aapi_v1

Bapi_v2

Capp

Dblueprint

Attempts:

3 left

💡 Hint

Common Mistakes

Using the app object instead of the blueprint in register_blueprint.

Confusing blueprint names like api_v2 instead of api_v1.

You register the blueprint object api_v1 with the Flask app to enable the routes under '/api/v1'.

2fill in blank

medium

Complete the code to create a second blueprint for API version 2 with prefix '/api/v2'.

Flask

api_v2 = Blueprint('v2', __name__, url_prefix=[1])

@api_v2.route('/hello')
def hello_v2():
    return 'Hello from version 2!'

app.register_blueprint(api_v2)

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

A'/api/v2'

B'/v2/api'

C'/api/version2'

D'/api/v1'

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong URL prefix that does not match the version.

Forgetting the quotes around the string prefix.

The URL prefix for version 2 API is '/api/v2' to keep versioning consistent.

3fill in blank

hard

Fix the error in the route decorator to correctly define a GET endpoint in the blueprint.

Flask

@api_v1.route('/status', methods=[1])
def status():
    return {'status': 'ok'}

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

A'GET'

B['POST']

C['GET']

DGET

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string without brackets like 'GET' instead of ['GET'].

Using the wrong HTTP method like 'POST' when GET is needed.

The methods argument expects a list of HTTP methods as strings, so ['GET'] is correct.

4fill in blank

hard

Fill both blanks to register blueprints for v1 and v2 with the Flask app.

Flask

app = Flask(__name__)

app.[1]_blueprint(api_v1)
app.[2]_blueprint(api_v2)

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

Aregister

Badd

Dattach

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-existent methods like add_blueprint or attach_blueprint.

Using different methods for each blueprint.

The correct method to add a blueprint to the app is register_blueprint.

5fill in blank

hard

Fill all three blanks to create a versioned API blueprint with a route that returns JSON.

Flask

from flask import Blueprint, jsonify

api_[1] = Blueprint('v[2]', __name__, url_prefix=[3])

@api_[1].route('/info')
def info():
    return jsonify({'version': 'v[2]', 'status': 'running'})

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

A1

B'/api/v1'

C2

D'/api/v2'

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing version numbers between variable names and URL prefixes.

Forgetting quotes around the URL prefix string.

The blueprint variable and name use '1' for version 1, and the URL prefix is '/api/v1'.

Practice

1. What is the main purpose of using Blueprints for API versioning in Flask?

easy

A. To store user session data securely

B. To speed up the Flask server automatically

C. To organize different API versions with separate URL prefixes

D. To create database models for each API version

Solution

1. Step 1: Understand Blueprints role in Flask

   Blueprints allow grouping routes and related code logically.

2. Step 2: Connect Blueprints to API versioning

   Using url_prefix in Blueprints lets you separate API versions by URL path.

3. Final Answer:

   To organize different API versions with separate URL prefixes -> Option C

4. Quick Check:

   Blueprints + url_prefix = versioned APIs [OK]

Hint: Blueprints + url_prefix separate API versions clearly [OK]

Common Mistakes:

• Thinking Blueprints speed up the server
• Confusing Blueprints with session management
• Assuming Blueprints create database models

2. Which of the following is the correct way to create a Blueprint for API version 1 with prefix '/api/v1'?

easy

A. bp = Blueprint('api_v1', __name__, url_prefix='/api/v1')

B. bp = Blueprint('api_v1', url_prefix='/api/v1')

C. bp = Blueprint(__name__, 'api_v1', url_prefix='/api/v1')

D. bp = Blueprint('api_v1', __name__, prefix='/api/v1')

Solution

1. Step 1: Recall Blueprint constructor parameters

   Blueprint(name, import_name, url_prefix=...)

2. Step 2: Identify correct syntax

   bp = Blueprint('api_v1', __name__, url_prefix='/api/v1') uses correct order and url_prefix keyword.

3. Final Answer:

   bp = Blueprint('api_v1', __name__, url_prefix='/api/v1') -> Option A

4. Quick Check:

   Blueprint(name, __name__, url_prefix=...) correct [OK]

Hint: Blueprint needs name, __name__, and url_prefix keyword [OK]

Common Mistakes:

• Omitting __name__ parameter
• Using 'prefix' instead of 'url_prefix'
• Swapping parameter order incorrectly

3. Given this Flask app code, what URL will return 'Hello from v2!'?

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

bp_v1 = Blueprint('v1', __name__, url_prefix='/api/v1')
@bp_v1.route('/hello')
def hello_v1():
    return 'Hello from v1!'

bp_v2 = Blueprint('v2', __name__, url_prefix='/api/v2')
@bp_v2.route('/hello')
def hello_v2():
    return 'Hello from v2!'

app.register_blueprint(bp_v1)
app.register_blueprint(bp_v2)

medium

A. /api/v2/hello

B. /hello

C. /v2/hello

D. /api/v1/hello

Solution

1. Step 1: Check Blueprint url_prefix for v2

   Blueprint 'v2' uses url_prefix='/api/v2'.

2. Step 2: Check route path inside v2 Blueprint

   Route is '/hello', so full path is '/api/v2/hello'.

3. Final Answer:

   /api/v2/hello -> Option A

4. Quick Check:

   Blueprint prefix + route = full URL [OK]

Hint: Combine url_prefix and route path for full URL [OK]

Common Mistakes:

• Ignoring url_prefix and using only route path
• Confusing v1 and v2 prefixes
• Assuming route is registered at root '/'

4. What is wrong with this Flask code for versioned API Blueprints?

bp_v1 = Blueprint('v1', __name__, url_prefix='/api/v1')
@bp_v1.route('/data')
def data_v1():
    return 'Data v1'

app.register_blueprint(bp_v1)

bp_v2 = Blueprint('v2', __name__, url_prefix='/api/v2')
@bp_v1.route('/data')
def data_v2():
    return 'Data v2'

app.register_blueprint(bp_v2)

medium

A. Functions cannot return strings directly

B. Blueprints cannot have the same route path

C. url_prefix should be set on app, not Blueprint

D. The second route decorator uses bp_v1 instead of bp_v2

Solution

1. Step 1: Identify route decorators and Blueprints

   The second route uses @bp_v1.route but should use @bp_v2.route.

2. Step 2: Understand impact of wrong decorator

   This causes the second function to register on the first Blueprint, not the second.

3. Final Answer:

   The second route decorator uses bp_v1 instead of bp_v2 -> Option D

4. Quick Check:

   Route decorator must match Blueprint instance [OK]

Hint: Match route decorator to correct Blueprint instance [OK]

Common Mistakes:

• Using wrong Blueprint for route decorator
• Thinking url_prefix belongs on app
• Believing functions can't return strings

5. You want to add a new API version 3 with a Blueprint and share a common route '/status' that returns different messages per version. Which approach correctly implements this in Flask?

hard

A. Define '/status' route only once on app without Blueprints and check version from headers

B. Create separate Blueprints for v1, v2, v3 each with url_prefix and define '/status' route inside each Blueprint

C. Create one Blueprint with url_prefix='/api' and use if-else inside '/status' route to check version

D. Use Flask extensions to automatically version APIs without Blueprints

Solution

1. Step 1: Understand version separation with Blueprints

   Each API version should have its own Blueprint with distinct url_prefix.

2. Step 2: Define '/status' route separately in each Blueprint

   This allows each version to return its own message cleanly and maintainably.

3. Final Answer:

   Create separate Blueprints for v1, v2, v3 each with url_prefix and define '/status' route inside each Blueprint -> Option B

4. Quick Check:

   Separate Blueprints per version = clean versioning [OK]

Hint: Use separate Blueprints per version for clean route separation [OK]

Common Mistakes:

• Trying to handle versions inside one route with if-else
• Defining routes only once without version separation
• Relying on extensions without understanding Blueprints