Drupal - How to set admin theme for a route?
You're looking for the _admin_route option:
aggregator.feed_add:
path: '/aggregator/sources/add'
defaults:
_controller: '\Drupal\aggregator\Controller\AggregatorController::feedAdd'
_title: 'Add feed'
requirements:
_permission: 'administer news feeds'
options:
_admin_route: TRUE
module.myroute:
path: '/path/path2'
defaults:
_controller: 'Drupal\module\Controller\MyController::add'
_title: 'Add element'
options:
_admin_route: 'TRUE'
You need to use ' ' around TRUE, if not, you will get 'InvalidArgumentException: Routing requirement for "options" must be a string'