There is an issue on Yii2 to redirecting / urls to /frontend/web.
In other words we need a way to hidden /frontend/web from addresses.
We will do this without changing Apache configuration and creating virtual host or setting document root (It's good for share hostings that we have not access to apache.conf)
There are a few issues with the other solutions I originally used that I found from other wikis. I address the issues I had in this much simpler and shorter way. I am also going to explain what is going into way more detail than others to help people understand what's going on.
With the adoption of PJax on Yii2 things have change quite a bit with GridView when it comes to work with them in AJAX mode. It will probably be confusing at the beginning, but then you will soon realize how powerful the new approach is.
If you are coming over to Yii 2 from Yii 1.x, you may have already read this useful wiki for creating dependent dropdowns.
You can use a similar approach in Yii 2 to do the same. But if you are looking at a prebuilt solution that helps you manage it easier, read along.