Flask project structure conventions - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import Flask and create an app instance.

Flask

from flask import [1]
app = [1](__name__)

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

AFlask

BApp

CFlaskApp

Dflask

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase 'flask' instead of 'Flask'.

Trying to create app with a wrong class name.

You import the Flask class from the flask package and create an app instance by calling Flask(__name__).

2fill in blank

medium

Complete the code to define a route for the home page.

Flask

@app.[1]('/')
def home():
    return 'Hello, Flask!'

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

Apath

Burl

Croute

Dendpoint

Attempts:

3 left

💡 Hint

Common Mistakes

Using '@app.url' or '@app.path' which do not exist.

Missing the decorator entirely.

The @app.route decorator defines the URL route for the function below it.

3fill in blank

hard

Fix the error in the app run command to enable debug mode.

Flask

if __name__ == '__main__':
    app.run(debug=[1])

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

A'True'

B1

Ctrue

DTrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'True' as a string instead of the boolean True.

Using lowercase 'true' which is not valid in Python.

The debug parameter expects a boolean value True without quotes.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension mapping endpoints to their view function names.

Flask

routes = {endpoint: func[1] for endpoint, func in app.[2].items()}

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

A.__name__

Bview_functions

C.__doc__

D.__str__

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect attributes that do not exist on app.

Trying to call methods instead of accessing attributes.

app.view_functions is a dictionary mapping endpoint names (which correspond to URL rules) to view functions. Iterate with .items() and use func.__name__ for the function name.

5fill in blank

hard

Fill all three blanks to create a Flask blueprint and register it.

Flask

from flask import Blueprint

bp = Blueprint('[1]', __name__, url_prefix='[2]')

app.[3](bp)

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

Aauth

B/auth

Cregister_blueprint

Droute

Attempts:

3 left

💡 Hint

Common Mistakes

Using '@app.route' instead of 'register_blueprint'.

Missing the slash in the URL prefix.

Using the wrong blueprint name.

Blueprints are created with a name like 'auth' and a URL prefix like '/auth'. They are registered on the app with app.register_blueprint(bp).

Practice

1. Which folder is conventionally used to store HTML files in a Flask project?

easy

A. templates

B. static

C. app

D. config

Solution

1. Step 1: Understand Flask folder roles

   Flask uses a folder named templates to hold HTML files for rendering views.

2. Step 2: Identify correct folder for HTML

   Since HTML files are templates, they belong in the templates folder, not static or others.

3. Final Answer:

   templates -> Option A

4. Quick Check:

   HTML files go in templates [OK]

Hint: HTML files live in templates folder by Flask convention [OK]

Common Mistakes:

• Confusing static folder for HTML files
• Putting HTML files directly in app folder
• Using config folder for templates

2. Which file is used to initialize a Flask app package inside the app folder?

easy

A. run.py

B. config.py

C. __init__.py

D. app.py

Solution

1. Step 1: Recognize Python package initialization

   Python packages use __init__.py to initialize modules and setup code.

2. Step 2: Apply to Flask app folder

   In Flask, the app folder is a package, so __init__.py initializes the Flask app instance.

3. Final Answer:

   __init__.py -> Option C

4. Quick Check:

   __init__.py initializes app package [OK]

Hint: Use __init__.py to initialize app package in Flask [OK]

Common Mistakes:

• Using run.py to initialize app package
• Confusing config.py with initialization
• Naming app.py as initializer

3. Given this Flask project structure:

myproject/
 ├── app/
 │    ├── __init__.py
 │    ├── routes.py
 │    ├── templates/
 │    │    └── home.html
 │    └── static/
 │         └── style.css
 ├── config.py
 └── run.py

Which file is typically used to start the Flask application?

medium

A. config.py

B. app/__init__.py

C. app/routes.py

D. run.py

Solution

1. Step 1: Identify the purpose of run.py

   In Flask projects, run.py is commonly used as the entry point to start the app server.

2. Step 2: Differentiate from other files

   config.py holds settings, __init__.py initializes app, and routes.py defines routes, but none start the server directly.

3. Final Answer:

   run.py -> Option D

4. Quick Check:

   run.py starts Flask app [OK]

Hint: run.py usually starts the Flask app server [OK]

Common Mistakes:

• Trying to run config.py to start app
• Running __init__.py directly
• Running routes.py as main file

4. You have this run.py file:

from app import app

if __name__ == '__main__':
    app.run(debug=true)

But running python run.py gives an ImportError: cannot import name 'app'. What is the likely cause?

medium

A. run.py is missing the Flask import statement

B. The 'app' variable is not defined in app/__init__.py

C. The templates folder is missing

D. Debug mode cannot be set in run.py

Solution

1. Step 1: Understand the import error

   The error means app is not found inside the app package's __init__.py.

2. Step 2: Check app/__init__.py for app variable

   Usually, app = Flask(__name__) is defined in __init__.py. If missing, import fails.

3. Final Answer:

   The 'app' variable is not defined in app/__init__.py -> Option B

4. Quick Check:

   app must be defined in __init__.py [OK]

Hint: Ensure app variable is defined in __init__.py before importing [OK]

Common Mistakes:

• Assuming missing Flask import causes this error
• Thinking templates folder affects imports
• Believing debug mode setting causes import error

5. You want to organize a Flask project with multiple blueprints for different features. Which structure best supports this while following Flask conventions?

hard

A. myproject/
├── app/
│ ├── __init__.py
│ ├── auth/
│ │ ├── __init__.py
│ │ └── routes.py
│ ├── blog/
│ │ ├── __init__.py
│ │ └── routes.py
│ ├── templates/
│ └── static/
├── config.py
└── run.py

B. myproject/
├── auth/
│ ├── __init__.py
│ └── routes.py
├── blog/
│ ├── __init__.py
│ └── routes.py
├── templates/
├── static/
├── config.py
└── run.py

C. myproject/
├── app.py
├── auth_routes.py
├── blog_routes.py
├── templates/
├── static/
├── config.py
└── run.py

D. myproject/
├── app/
│ ├── routes.py
│ ├── templates/
│ └── static/
├── auth.py
├── blog.py
├── config.py
└── run.py

Solution

1. Step 1: Understand blueprint organization

   Blueprints are best organized as sub-packages inside the main app package, each with its own __init__.py and routes.

2. Step 2: Evaluate options for Flask conventions

   myproject/
    ├── app/
    │    ├── __init__.py
    │    ├── auth/
    │    │    ├── __init__.py
    │    │    └── routes.py
    │    ├── blog/
    │    │    ├── __init__.py
    │    │    └── routes.py
    │    ├── templates/
    │    └── static/
    ├── config.py
    └── run.py

   places blueprints inside app/ folder as sub-packages, keeping templates and static centralized, which is recommended.

3. Final Answer:

   Option A structure best supports multiple blueprints with Flask conventions -> Option A

4. Quick Check:

   Blueprints as sub-packages inside app folder [OK]

Hint: Put blueprints as subfolders inside app with __init__.py [OK]

Common Mistakes:

• Placing blueprints outside app folder
• Using single file for all routes
• Not including __init__.py in blueprint folders