Drupal 8/9: Theme negotiation based on condition plugins
Sooner, the European Commission Drupal project I'm working on, will transition to a new theme. During the transition, some pages will be still displayed using the the old theme. I've looked around for a Drupal module that knows to render a certain page using a specific theme and found Switch Page Theme. The big impediment with this module is that it mainly checks the page path. And this is more or less hardcoded. There's no way to add arbitrary conditions, such as a route condition, which is the one I'm more interesting in.
As proposing a change to the existing module would have been a too disruptive and hard to address in terms of backwards compatibility issues, I've built the Theme Negotiation by Rules module, which has... [read more]