How to Use Conditional Rendering for HTML Attributes in Fat-Free Framework Templates

Описание: Learn how to correctly implement conditional rendering in Fat-Free Framework templates to dynamically set HTML attributes like 'selected' without syntax errors.
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This video is based on the question https://stackoverflow.com/q/79400169/ asked by the user 'Universe' ( https://stackoverflow.com/u/1281063/ ) and on the answer https://stackoverflow.com/a/79400315/ provided by the user 'n0nag0n' ( https://stackoverflow.com/u/721019/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

When working with the Fat-Free Framework (F3), you might want to conditionally set HTML attributes such as selected within <option> tags based on the user's data. This is a common need in forms where the displayed selection reflects user properties.

The Problem

Trying to use a ternary operator without the full syntax inside F3 template tags can cause syntax errors. For example, this snippet causes an error:

[[See Video to Reveal this Text or Code Snippet]]

The error occurs because F3 templates are essentially PHP code, and PHP requires both parts of the ternary operator:

[[See Video to Reveal this Text or Code Snippet]]

Omitting the false expression triggers a syntax error.

The Correct Solution

Add the false case (an empty string if you want nothing printed) to complete the ternary:

[[See Video to Reveal this Text or Code Snippet]]

This will render the selected attribute only if the condition matches. Otherwise, it prints nothing.

Summary

Fat-Free Framework templates interpret code as PHP.

PHP requires a complete ternary operator with both true and false parts.

To conditionally set an attribute, use the full ternary like: condition ? "selected" : "".

This approach ensures clean conditionals without syntax errors and is easy to maintain.