Flask Templating (Jinja2)

The front-end begins with the server. Jinja2 provides the power to build dynamic, reusable HTML.

Pattern & Inheritance

• Base Layout: Use base.html for common headers, footers, and styles.
• Block Inheritance: Use {% block content %} to allow child templates to inject their specific content.

Reusability

• Macros: Like functions for HTML (e.g., a reusable button or form field).
• Includes: Component-level reusability for navigation bars or sidebars.

Logic & Context

• Control Flow: {% if user.is_authenticated %}, {% for item in items %}.
• Filters: Formatting data directly in the template (e.g., {{ date|format_date }}).

Best Practices

• Never Render Raw HTML: Ensure variables are escaped to prevent XSS.
• Logic Placement: Keep complex calculations in Python, and only use templating for display logic.