Flask Introduction: Mastering Routes and View Functions from Scratch
This article is an introductory guide to Flask routes and view functions. First, install Flask using `pip install flask`. A basic example (code in `app.py`) demonstrates the first application: create a `Flask` instance, define the root route with `@app.route('/')`, and have the view function `index()` return "Hello, Flask!". After running, access `http://127.0.0.1:5000/` to view the result. Routes map URLs to view functions, categorized into two types: static routes (e.g., `/about` bound to the `about()` function) and dynamic routes (using `<parameter_name>`, e.g., `/user/<username>`, supporting type constraints like `int:post_id`). View functions process requests: they can return strings, HTML, and support HTTP methods (e.g., GET/POST) via the `methods` parameter. To return JSON, use `jsonify`. Start the development server with `app.run(debug=True)` for easier debugging. Key points: Route definition mapping, dynamic parameter handling for variable paths, view functions processing requests and returning responses (text, HTML, JSON, etc.), and specifying HTTP methods through `methods`. Mastering these enables building simple web applications, with subsequent topics to explore templates and static files.
Read MoreStep-by-Step Guide: Flask Routes and View Functions, Build Your First Web Page in 10 Minutes
Flask is a lightweight Python Web framework, simple and flexible, suitable for beginners, and supports extensibility as needed. Installation requires Python 3.6+, and can be done via `pip install flask`. To verify, use `flask --version`. The core of a basic application: Import the Flask class and instantiate an `app` object; define the root route with `@app.route('/')`, binding to the view function `home()`, which returns content (e.g., "Hello, Flask!"); `app.run()` starts the development server (default port 5000). For advanced support, dynamic routing is available, such as `/user/<username>`, where the view function receives parameters to implement personalized responses, supporting types like `int` and `float`. Core concepts: Routes bind URLs to functions, view functions handle requests and return content, and `app.run()` starts the service. Key techniques: `if __name__ == '__main__'` ensures the service starts when the script is run directly, and dynamic routing enhances page flexibility.
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