Learning Flask from Scratch: Template Inheritance and Variable Rendering
This article introduces the core of the Flask template system, which uses the Jinja2 engine to implement dynamic HTML rendering. Key skills include: 1. **Variable Rendering**: Embed Python variables (supporting strings, numbers, lists, dictionaries) in HTML using the `{{ variable }}` syntax. Variables are passed via `render_template` in view functions, with support for loops (`{% for %}`) and conditional checks (`{% if %}`). 2. **Template Inheritance**: Define a base template (base.html) with `{% block %}` placeholders. Child templates inherit from the base via `{% extends %}` and override content blocks to reuse common structures like navigation bars and footers, avoiding code duplication. The project structure includes app.py (main program) and a templates folder for storing templates. The article also addresses common issues and solutions, summarizing that variable rendering and template inheritance are fundamental to Flask development.
Read MoreLearn Flask Easily: Detailed Explanation of Request and Response Objects
In Flask, requests and responses are the core of web development. A request refers to data sent by a client (e.g., a browser), which can be accessed through the `request` object. Key properties include: `method` (HTTP method like GET/POST), `args` (URL parameters), `form` (form data), `cookies`, and `headers`. For example, GET requests retrieve parameters using `request.args`, while POST requests access form data via `request.form`. A response is the result returned by the application. Common methods to return responses include: returning a string, HTML (using `render_template`), JSON (using `jsonify`), redirection (using `redirect`), and custom status codes (e.g., 404). In a comprehensive example, form submissions (POST) use `request.form` to retrieve data. After validation, the application returns either a JSON or HTML response to achieve interaction. Key principles: GET is used to fetch data (parameters in the URL), while POST is for data submission (parameters in the request body). For responses, `jsonify` returns JSON, `render_template` returns HTML pages, `redirect` performs redirection, and `url_for` resolves route URLs.
Read MoreRESTful API Getting Started: Developing a Simple GET Data Interface with Flask
This article introduces the concept of RESTful APIs and implementing a GET interface with Flask. RESTful APIs are HTTP-based front-end and back-end interaction architectures centered on resources, manipulating resources through GET/POST/PUT/DELETE operations, stateless, and returning JSON data. Flask is chosen for its lightweight and flexibility, making it suitable for beginner development. Flask can be installed via `pip install flask` (virtual environment is optional). Implementation involves two steps: first, define the root path `/` to return "Hello, Flask!", with the core code being the `@app.route('/')` decorator and the `return` statement with a string; second, implement the `/users` interface to return user list JSON data, requiring the import of `jsonify` and returning the converted list. After starting the application, access `http://localhost:5000/users` through a browser, curl, or Postman for testing. Core steps include: importing Flask, initializing the application, defining route functions, returning data, and starting the service. Future extensions can include more routes or database integration.
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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