prefix_url - Twig Function

Historically, Contao made use of the <base href="…"> HTML tag so that all relative URLs are always relative to this base. In Contao 5 however, we are moving away from that and instead always output path absolute URLs. In order to make sure though that any relative link that might have been input in the back end somewhere will continue to work even without the base tag, the prefix_url helper function exists, which will automatically prepend the base path of the request for any relative URL.

{# Make sure the "userGeneratedUrl" is always path absolute #}
<a href="{{ prefix_url(userGeneratedUrl|insert_tag) }}">

Arguments

• url: The relative URL to be prefixed with the requests’s base path, if applicable.