Control Flow
Explore how to apply control flow statements like loops and conditionals within Jinja2 templates in Flask. Learn to render dynamic collections and conditionally format output while keeping business logic separate from presentation for clean, maintainable web interfaces.
In previous lessons, we learned how to bind variables to our templates, but we were limited to rendering individual items by their index. Real-world applications require us to process dynamic collections, such as lists of users or inventory items, and display them according to specific logical rules. By implementing control flow directly within our Jinja2 templates, we keep our presentation layer responsive to the data provided by our Flask view functions, allowing us to build complex, data-driven interfaces.
Introduction to template logic
Template logic allows us to perform basic programming tasks, like loops and branches, directly inside our HTML files. It is important to distinguish this from backend business logic; while we perform data fetching, filtering, and sorting in our Python ...