Twig check if file exists
You can create your own function or test and just pass the arguments to the PHP function.
$test = new Twig_SimpleTest('ondisk', function ($file) { return file_exists($file);});And then in your template:
{% if filename is ondisk %} blah{% endif %}Unfortunately is exists sounds weird in English. Perhaps a function would make more sense.
Creating a custom function is just fine if you really need to make the validation on template side. But Twig is not meant to be used that way.
You can just make the valitadion php side and pass a flag to your template:
PHP
$filename = '/path/to/foo.txt';$file_exists = file_exists($filename);// ...$app->render( 'yourTemplate', array( 'file_exists' => $file_exists ));TWIG
{% if file_exists %} do stuff{% endif %}Disclaimer: I don't know the exact way to render a twig template using Slim (Symfony2 guy here), but it's same logic.