Apply Filter Twig Extension Bundle Laravel Package

Getting Started

Minimal Setup

1. Installation:

   composer require danilovl/apply-filter-twig-extension-bundle
   

   Ensure Danilovl\ApplyFilterTwigExtensionBundle\ApplyFilterTwigExtensionBundle::class is registered in config/bundles.php.

2. First Use Case: Apply a built-in PHP filter dynamically in Twig:

   {{ apply_filter('upper', 'hello') }}  {# Outputs: HELLO #}
   

   Test with common filters like lower, trim, ucfirst, or json_encode.

Where to Look First

• Tests: The tests/ directory contains practical examples of filter usage.
• Bundle Docs: Check src/DependencyInjection/ for configuration options (if any).
• Twig Docs: Review Symfony’s Twig documentation for supported filters.

Implementation Patterns

Dynamic Filter Application

Use apply_filter to chain or conditionally apply filters:

{% set text = '  hello world  ' %}
{{ apply_filter('trim', apply_filter('lower', text)) }}  {# Outputs: hello world #}

Conditional Filter Logic

Leverage Twig’s control structures:

{% set filter = isAdmin ? 'upper' : 'lower' %}
{{ apply_filter(filter, 'test') }}

Custom Filter Integration

Extend the bundle by registering custom PHP filters in your Twig environment:

// src/Twig/AppExtension.php
use Twig\Extension\AbstractExtension;
use Twig\TwigFunction;

class AppExtension extends AbstractExtension
{
    public function getFunctions(): array
    {
        return [
            new TwigFunction('custom_filter', [$this, 'customFilter']),
        ];
    }

    public function customFilter(string $input): string
    {
        return strrev($input); // Example: reverse string
    }
}

Then use it in Twig:

{{ apply_filter('custom_filter', 'hello') }}  {# Outputs: olleh #}

Performance Considerations

• Cache Filters: Precompute filter results in PHP when possible to avoid repeated Twig evaluations.
• Avoid Overuse: Dynamic filters can impact rendering speed if overused in loops.

Gotchas and Tips

Pitfalls

1. Filter Availability:

   • Only PHP’s built-in filters (e.g., strtolower, json_encode) work by default.
   • Custom filters require manual registration (see Custom Filter Integration above).
   • Debug Tip: Use {{ dump(apply_filter('filter_name', var)) }} to verify filter behavior.

2. Error Handling:

   • Invalid filter names throw Twig\Error\RuntimeError. Validate dynamically passed filter names in PHP:

     if (!function_exists($filterName)) {
         throw new \RuntimeException("Filter '$filterName' not found.");
     }
     

3. Security:

   • Sanitize dynamic filter inputs to prevent arbitrary code execution:

     {% set allowedFilters = ['upper', 'lower', 'trim'] %}
     {% if filterName in allowedFilters %}
         {{ apply_filter(filterName, text) }}
     {% endif %}
     

Debugging Tips

• Check Filter Names: Ensure filter names match PHP’s exact function names (e.g., strtoupper vs. upper).
• Twig Profiler: Use Symfony’s Twig profiler to inspect filter execution time:

  // config/packages/twig.yaml
  twig:
      debug: '%kernel.debug%'
      profiler: '%kernel.debug%'
  

Extension Points

1. Override Default Filters: Subclass the bundle’s extension to modify or replace filters:

   // src/Twig/ApplyFilterExtension.php
   use Danilovl\ApplyFilterTwigExtensionBundle\Twig\ApplyFilterExtension as BaseExtension;
   
   class ApplyFilterExtension extends BaseExtension
   {
       protected function getFilters(): array
       {
           return array_merge(parent::getFilters(), [
               'custom' => [$this, 'customFilter'],
           ]);
       }
   }
   

2. Add Filter Arguments: Extend the bundle to support filter arguments (e.g., apply_filter('substr', 'hello', 1, 2)):

   // Custom extension logic
   public function applyFilter(string $filter, mixed $var, array $args = []): mixed
   {
       if (is_callable($filter)) {
           return call_user_func_array($filter, array_merge([$var], $args));
       }
       // Fallback to default behavior
   }
   

Configuration Quirks

• No Config File: The bundle has no config/packages/ file, meaning all behavior is runtime-driven.
• Bundle Auto-Registration: Works with Symfony Flex; no manual AppKernel registration needed.