Yii3 - How to start

Comparing #43 with #44

Revision #44 was created by rackycz rackycz on Apr 1, 2026, 8:55:48 PM.

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First of all, learn what [PHP Standards Recommendations](https://en.wikipedia.org/wiki/PHP_Standard_Recommendation) by [Framework Interoperability Group (FIG)](https://www.php-fig.org/psr) are. It will help you understand why so many "weird" PSR imports are in the Yii3 code. In short: These interfaces help authors of different frameworks to write compatible classes so they can be reused in any other framework following these principles.

## Dependency injection + container
Check [this YouTube video](https://www.youtube.com/watch?v=TqMXzEK0nsA) for explanation


 
## 135 packages by Yii
 
 
The Yii team split the functionalities into 135 packages which you should check in advance to know what is available. Their are listed [here](https://www.yiiframework.com/status/3.0) or the same is also [here](https://www.yiiframework.com/doc/api/3.0).
 
 
For example [log in](https://github.com/yiisoft/user) and [RBAC](https://github.com/yiisoft/rbac), which can be stored in [DB](https://github.com/yiisoft/rbac-db) or in [PHP files](https://github.com/yiisoft/rbac-php/). And many more like "active-record" (which is now finished),"form-model" or "boostrap5".
 
 
## invoke()
The `__invoke()` public method is called when you call the **instance** as a method. (Therefore the constructor was already executed)

```php
$obj = new MyObj(); // Now the __construct() is executed.
$obj(); // Now the __invoke() is executed (The instance is needed!)
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