It seems many people is trying to make Wordpress and Yii work together. I got stuck with the same problem, but now I think I have achieved doing it, after a lot of hard thinking and many work hours spent.
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)
This is a reference to be used for Model rule validation and is compiled from the Yii documentation and code. The purpose is to have all the information gathered in one place instead of scattered. This reference is not an intro.
See The Definitive Guide to Yii, Declaring Validation Rules for a tutorial.
In this mini howto I would like to show how to add a required captcha field in the login form, after a defined number of unsuccessfull attempts.
To do this, I will use the blog demo that you have in default Yii download package (path/to/yii/demos/blog).
I have seen a couple of articles about how to integrate external libraries to debug our PHP code (i.e. firePHP) but after you read this article you will realize that there is no need for such libraries when using Yii.