Easy Trick to Show Translation only if it Exists in Symfony

I had a problem. I needed to show a translated piece of text based on a route parameter. For instance, I wanted route /category/symfony to show a translated description of symfony.

What I tried was to create translations like this

category:
symfony: Symfony is a framework and...

Now the problem I had is that I don't want to write descriptions to all of the categories. For instance, if I tried to access route /category/twig I would only see category.twig because the translation is missing.

I was a bit surprised that I couldn't find a way to show an empty string if the translation key is not defined. I came up with a simple solution like this inside the twig template

{# Set the translation key #}
{% set translationKey = "category." ~ category %}
{% if (translationKey | trans) != translationKey %}
<p>{{ translationKey | trans }}</p>
{% endif %}

That does the trick. This piece of code will show the translation only if the trans filter returns something else than the translation key itself. Probably not the most elegant solution but it works for this use case.