A relative route is a route without a leading slash, such as "view", "post/view".
- If the route is an empty string, the current [[\yii\web\Controller::route|route]] will be used;
- If the route contains no slashes at all, it is considered to be an action ID
of the current controller and will be prepended with [[\yii\web\Controller::uniqueId]];
- If the route has no leading slash, it is considered to be a route relative
to the current module and will be prepended with the module's uniqueId.
Starting from version 2.0.2, a route can also be specified as an alias. In this case, the alias
will be converted into the actual route first before conducting the above transformation steps.