Flask is a lightweight, flexible Python web framework known for its simplicity and ease of use. It’s classified as a microframework because it doesn’t enforce strict project structure or provide many built-in features. This allows developers to customize the application to their specific needs.
Core Components
- WSGI Application: Flask applications are WSGI (Web Server Gateway Interface) compliant, enabling them to work with various web servers.
- Routing: Defines URL patterns and maps them to Python functions (views).
- Templating: Uses Jinja2 template engine to create dynamic HTML content.
- Request and Response Objects: Handles incoming requests and generates responses.
Basic Structure
A simple Flask application typically consists of:
- Import Flask:
- Python
from flask import Flask
- Create an app instance:
- Python
app = Flask(__name__)
- Define routes and views:
- Python
@app.route('/') def index():return 'Hello, World!'
- Python
- Run the application:
- Python
if __name__ == '__main__':app.run(debug=True)
Key Features
- Flexibility: Can be easily extended with additional libraries and components.
- Simplicity: Minimalistic core with a straightforward API.
- Performance: Efficient for small to medium-sized applications.
- Community: Strong community support and extensive documentation.
Flask is ideal for building RESTful APIs, small web applications, and prototypes. Its flexibility makes it a popular choice for developers who prefer a minimalist approach.
Introduction to Flask
Why use Flask?
For small to medium-sized projects, APIs, and rapid prototyping.
What is the core of a Flask application?
A WSGI application instance.
How do I define a route in Flask?
Use the @app.route() decorator.
What is a view function in Flask?
A Python function that handles incoming requests and returns a response.
How do I pass URL parameters?
Use <variable_name> in the route definition.
How do I render a template in Flask?
Use the render_template() function.
How do I pass data to a template?
Pass a dictionary as the render_template() function’s kwargs.
Can I use Flask for large-scale applications?
While possible, Flask is better suited for smaller projects. For larger applications, consider Django.
How do I handle errors in Flask?
Use error handlers with @app.errorhandler().