Symfony2 and Twig - Check if an asset exists

Question

I have a symfony2 project using twig templates.

I am displaying some images and would like to display the image only if the specific asset exists.

I have this:

{% if asset('bundles/sciforumversion2/images/logos/'~conf.img) %}
    <img style="width: 60px; float:right; margin-right: 15px;" src="{{ asset('bundles/sciforumversion2/images/logos/')}}{{ conf.img }}"/>
{% endif %}

But the if condition is always true.

Any idea please? Thank you.

Solution 1

If you want to check if an asset exists, you can create a Twig extension to implement the function.

PHP In your Twig\Extension directory, create AssetExistsExtension.php with the following content:

<?php

namespace Fuz\TestBundle\Twig\Extension;

use Symfony\Component\HttpKernel\KernelInterface;

class AssetExistsExtension extends \Twig_Extension
{

    private $kernel;

    public function __construct(KernelInterface $kernel)
    {
        $this->kernel = $kernel;
    }

    public function getFunctions()
    {
        return array(
                'asset_exists' => new \Twig_Function_Method($this, 'asset_exists'),
        );
    }

    public function asset_exists($path)
    {
        $webRoot = realpath($this->kernel->getRootDir() . '/../web/');
        $toCheck = realpath($webRoot . $path);

        // check if the file exists
        if (!is_file($toCheck))
        {
            return false;
        }

        // check if file is well contained in web/ directory (prevents ../ in paths)
        if (strncmp($webRoot, $toCheck, strlen($webRoot)) !== 0)
        { 
            return false;
        }

        return true;
    }

    public function getName()
    {
        return 'asset_exists';
    }

}

YML And here is the configuration, to put in your services.yml file.

parameters:
    (...)
    fuz_tools.twig.asset_exists_extension.class: Fuz\TestBundle\Twig\Extension\Asset@ExistsExtension

services:
    (...)
    fuz_tools.twig.asset_exists_extension:
        class: '%fuz_tools.twig.asset_exists_extension.class%'
        arguments: ['@kernel']
        tags:
          - { name: twig.extension }

Twig To use this extension, on a twig file, use:

{% if asset_exists('bundles/fuztest/images/test.png') %}

Note: do not forget to replace namespaces to match with your project.

Solution 2

There's a typo in your code:

fuz_tools.twig.asset_exists_extension.class: Fuz\TestBundle\Twig\Extension\AssetsExistsExtension

should be

fuz_tools.twig.asset_exists_extension.class: Fuz\TestBundle\Twig\Extension\AssetExistsExtension

Comments

[Milos Cuculovic]

Thank you Sybio. This could work but I found another way, which works in my case. For each conference object, I have the image object, if the image is set, the image object will be null for a specific conference, so I can test it this way. But you answer is more complete and I will accept it. Thanks again.

[Alain Tiemblo]

-1,Your answer gives a way to check if a file exists, not specifically an asset.

[Alain Tiemblo]

My point is, you could inject kernel in your extension and use a proper method to check if an asset exists, I'll write my answer this will be better to explain.

[Barno]

I have add / in assets_exists TEST IMAGE => {% if asset_exists('/bundles/fuztest/images/test.png') %} YES ! asset_exists {% else %}NO asset_exists :({% endif %}

[esteemed.squire]

@Alain Tiemblo I've tried your solution and I'm looking for .jpg files if it exists to list out a <div> to display the image if not, don't display the image. I am using the following: {% if asset_exists('/images/.jpeg') %} and nothing is found even though the posts being listed have .jpeg files to them. Is using .jpeg the proper way to look for this? The images are in web/images

[Alain Tiemblo]

This Twig function checks if a real path exists. This mean, asset_exists('/images/some_image.jpg') will return true if some_image.jpg exists. You currently can't put a joker in the file name, but that's quite simple to implement. Replace if (!is_file($toCheck)) by if (count(glob($toCheck)) == 0). Then, use asset_exists('/image/*.jpeg').

[Sam]

You don't need to inject the whole kernel here - just the %kernel.root_dir% parameter.

[Alain Tiemblo]

Ohh yeah, you're right. This answer is a bit old, I'll update it when I'll have time. Thanks!

[Sam]

I took out the "well contained" check - realpath resolves symlinks, so in development (where I use assets:install --symlink), $toCheck was always outside the web-root by this stage (i.e. pointing to the original file under src).