In a nutshell, the task at hand is to mark (or render) a model attribute in the typical "_form.php" view file with the 'required' red asterisk while this attribute is not marked as required in the model's rule() method.
If you're interested only in the solution, jump ahead to the 'solution' section below.
There are scenarios when you work with DVCS (like Mercurial or Git) and CDbMessageSource. To my experience keeping the development database and production database in sync can be very time consuming. Plus, when working in a team, you never know when the database was updated.
I assume you are familiar with accessControl standard filter. It allows you to separate privileges to run some action from action code itself. There is however one problem with most common usage - you cannot use bizRules, at least based on some parameters passed to 'checkAccess' just because it is hard to pass them in accessRules() result.
This tutorial is not about allowing users to sign into your application by using any of the OAuth providers available with the official yii2-authclient extension, it is about how to interact with your Twitter account, the one you set for your Yii2 app to promote your site, using the Single Access Token technique.
I found a standard Yii app's protected folder structure nearly perfect. With a few simple moves and a little bit change to the code, I managed to bring it to the level, which I found as fully perfect. I want to share my point of view, in case someone would like to use this structure as well.