To extend the functionality of you web application relative to your requirements you are supposed to use existing yii core libraries or use external libraries. There are some steps to ensure security, uniqueness, modularity, performance and to avoid rework in future.
Sometime its very important to perform many actions/operation with limited time frame for friendly use, select2 provides a lot of such functionality , I just extend it tags functionality to provide a quick use for developer to save time, as I spent much time on it.
If you have read this wiki you would be aware of the yii2-detail-view extension and how it offers you an easy way to EDIT and VIEW your model data, toggle these modes, and other features. You can read the extension documentation and/or view a demo of this extension, to understand usage.
You have a multilingual application, and you want the URL of a page to be different for different languages, to account for SEO. The URL for the contact page for example should look like http://something.com/en/contact in english, and http://something.com/de/contact in german. This tutorial describes how to make it happen.
Note that currently selected language is always a part of the URL, and thus available to the application through $_GET. You don't have to use sessions variables to keep track of the language if you don't want to.
You would find having such a need in most Yii Projects. Your database needs a specific format to store date fields, while you may want to display it in different formats to the users on forms and other views.
The yii2-field-range extension enables you to easily setup ActiveField range fields with Bootstrap styling. You basically can setup two attributes joined together like a single field with combined validation error block.
I have had to do this a couple of times now so I figured I would share it with the community. I am going to keep this short because I really hope that you are familiar with jQueryUI's Sortable class before starting this tutorial.