Yii Framework

Appearance

Upgrading from Version 2.0 ​

Informanion

If you haven't used Yii2, you can skip this section and get directly to "getting started" section.

While sharing some common ideas and values, Yii 3 is conceptually different from Yii 2. There is no easy upgrade path, so first check maintenance policy and end of life dates for Yii 2 and consider starting new projects on Yii 3 while keeping existing ones on Yii 2.

PHP requirements ​

Yii3 requires PHP 8.0 or above. As a result, there are language features used that weren't used in Yii 2:

Preliminary refactoring ​

It's a good idea to refactor your Yii 2 project before porting it to Yii 3. That would both make porting easier and benefit the project in question while it's not moved to Yii 3 yet.

Use DI instead of service locator ​

Since Yii 3 is forcing you to inject dependencies, it's a good idea to prepare and switch from using service locator (Yii::$app->) to DI container.

If usage of DI container is problematic for whatever reason, consider moving all calls to Yii::$app-> to controller actions and widgets and passing dependencies manually from a controller to what needs them.

See Dependency injection and container for an explanation of the idea.

Introduce repositories for getting data ​

Since Active Record isn't the only way to work with a database in Yii 3, consider introducing repositories that would hide details of getting data and gather them in a single place you can later re-do:

php
class PostRepository
{
    public function getArchive()
    {
        // ...
    }
    
    public function getTop10ForFrontPage()
    {
        // ...
    }

}

Separate domain layer from infrastructure ​

In case you have a rich complicated domain, it's a good idea to separate it from infrastructure provided by framework that's all the business logic has to go to framework-independent classes.

Move more into components ​

Yii 3 services are conceptually similar to Yii 2 components, so it's a good idea to move reusable parts of your application into components.