I was wondering how to set-up the application parameters in the back-end to use them all around the application without the need of using the database and I came up with this solution, I hope it helps somebody else.
After a lot of research, everything I found on adding date range searching to a CGridView advanced search form seemed to involve adding two new public variables (e.g. $date_from, $date_to), 'safe' rules for the new variables, and a rather chunky if/elseif/else check in the search() method. This probably isn't a hassle for most, but because many of the tables in my database contain two or three and sometimes four date columns (e.g. date_created, date_modified, date_deleted etc.), it meant I was having to add up to eight public variables, the corresponding safe rules, and modifying the search() criteria for each date attribute. So, I set about creating a better way and I thought I'd share my work with the community.
Sometimes the active form we wish to use to edit/add a new element on our database is too small and we believe that is much better to use an AJAX'ed dialog/slide form rather than reloading the page to just display one or two fields.
One of the common requests I see in the forum is how to implement RBAC. While you can implement Yii 2's built-in RBAC, that might be too much for developers who are just starting with Yii 2 or have simpler needs. Sometimes you are looking for a fast solution and just want two flavors, user and admin. And even if you will eventually need more, you can use these methods as a starting point for developing your own features or move on to Yii 2's RBAC.