Jinja2 Template Engine: Dynamically Rendering Data in Web Pages with Flask (with Examples)

This article introduces the role of template engines in web development and the application of Jinja2 in Flask. Template engines solve the cumbersome problem of splicing backend data with frontend HTML, allowing developers to focus on separating data logic from page structure. Jinja2 is Flask's default template engine, with a concise syntax that supports variable substitution, conditional judgment, loops, filters, and other features. The basic process of using Jinja2 involves: first installing Flask, creating an application and defining routes, preparing backend data (such as user information and article lists), and rendering the template through render_template. Template files should be placed in the 'templates' folder, where data is embedded using {{ variables }}, conditional logic and loops are implemented with {% if %} and {% for %}, and filters are applied using the | operator to process data. Template inheritance, through base.html and child templates, promotes code reusability by reusing page structures. The core syntax of Jinja2 includes variable substitution, conditional judgment, loop traversal, and filters, while template inheritance further optimizes project structure. Mastering Jinja2 enables efficient implementation of dynamic page rendering and is a key tool for connecting data and interfaces in web development.