> For the complete documentation index, see [llms.txt](https://wplake.gitbook.io/advanced-views/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wplake.gitbook.io/advanced-views/layouts/code-fields/layout-controller.md).

# Layout Controller

In Advanced Views, the Layout Controller is a special PHP class allowing you to control the related [*Layout*](/advanced-views/getting-started/first-layout.md) behavior.

Using the Layout Controller, you can do the following:

1. Add extra variables to the *Layout* template
2. Define [Layout Ajax actions](/advanced-views/layouts/component-options/ajax-actions.md)
3. Define [Layout Rest Api actions](/advanced-views/layouts/component-options/rest-api-actions.md)

{% hint style="info" %}
If you opted for [vanilla PHP templates](/advanced-views/features/smart-templates/php-templates.md) or [Blade templates](/advanced-views/features/smart-templates/blade-templates.md), you can also load extra fields right inside the template. However, loading extra fields via the Controller is beneficial for advanced cases, as it splits responsibilities and provides access to the PHP-DI instance.  
{% endhint %}

## 1. How to use Layout Controller

Go to **Edit** your *Layout*.

Switch to the *Template* tab.

Scroll down until you see the *PHP Controller* field.

Add your PHP code.

Click on the **Update** button to save your *Layout*.

## 2. Layout Controller methods

The field with the snippet can be found in the **Template tab** of your *Layout*.

The snippet is a PHP code, which must return an instance of the `Layout_Controller_Base` class. 

* using the `get_variables()` method you can pass custom variables to the *Layout* template 
* using the `get_ajax_response()` method you define the Ajax callback for the block. [Read more](broken://pages/GmCOejBZuu1WvZmZpvlf) 
* using the `get_rest_api_response()` method you define the Rest api callback
* using the `get_object_id()` method you can get the id of the displaying object
* using the `get_custom_arguments()` method you can access the [custom arguments passed to the shortcode](https://docs.advanced-views.com/shortcode-attributes/common-arguments#id-4.-custom-arguments). The field is available in the both methods above.
* using the `get_default_variables()` method you can access to the default twig variables (that filled out automatically by the plugin)
* using the `get_container()` method you can access the PHP-DI Container (see the related chapter of this page) 

{% code overflow="wrap" %}

```php
<?php

declare(strict_types=1);

use Org\Wplake\Advanced_Views\Bridge\Controllers\Layout\Layout_Controller_Base;

return new class extends Layout_Controller_Base {
    /**
     * @return array<string,mixed>
     */
    public function get_variables(): array
    {
        return [
            // "custom_variable" => get_post_meta($this->get_object_id(), "your_field", true),
            // "another_var" => $this->get_custom_arguments()["another"] ?? "",
        ];
    }
    /**
     * @return array<string,mixed>
     */
    public function get_variables_for_validation(): array
    {
        // it's better to return dummy data here [ "custom_variable" => "dummy string", ]
        return $this->get_variables();
    }
    /**
     * @return array<string,mixed>
     */
    public function get_ajax_response(): array
	{
	    // $message = $this->get_container()->get(MyClass::class)->myMethod();
		return [
			// "message" => $message,
		];
	}
	/**
     * @return array<string,mixed>
     */
    public function get_rest_api_response(WP_REST_Request $request): array
	{
	    // $input = $request->get_json_params();
	    // $message = $this->get_container()->get(MyClass::class)->myMethod();
		return [
			// "message" => $message,
		];
	}
};

```

{% endcode %}

{% hint style="info" %}
Tip: if you pass custom variables using the `get_variables()` method, we recommend to change the `get_variables_for_validation()` method and return dummy data there.

Advanced Views has the built-in automatic template validation, which is called on the Publish or Update action. There is no sense to return real data in this case, and it's better to return dummy data, to avoid potential issues with missing functions.

For example, if you use WP functions inside, they may be front-end only, and aren't available in the wp-admin area, which will lead to the failed validation.&#x20;
{% endhint %}

## 3. PHP-DI support

[PHP-DI](https://php-di.org/) is a well-known dependency injection container. If you haven't used it, we recommend checking it out and harnessing its capabilities.

Advanced Views supports PHP-DI out-of-the-box. To simplify access to your theme's PHP class instances inside the Custom\_Data instances, you can employ the PHP-DI container. To do this, you need to define the container in your theme using the [`advanced_views/container`](broken://pages/17mz5ByUlebQDwXg78tS#container-pro) hook. Then, you can access it using the `get_container()` method in any method of the Custom\_Data class.

#### Example

A simple example is below:

#### 1. Define a container in your theme:&#x20;

```php
<?php

use DI\Container;

$container = new Container();

add_filter( 'advanced_views/container', function () use ( $container ) {
	return $container;
} );
```

#### 3. Request Container inside the Controller:

```php
<?php

declare(strict_types=1);

use Org\Wplake\Advanced_Views\Bridge\Controllers\Layout\Layout_Controller_Base;
use MyTheme\MyClass;

return new class() extends Layout_Controller_Base {
    /**
     * @return array<string,mixed>
     */
    public function get_variables(): array {
       $container = $this->get_container();
       $my_class = $container?->get( MyClass::class );

       return array(
          'my_var_with_complex_calculation' => $my_class?->get_var(),
       );
    }
};
```

If you're unfamiliar with [PHP-DI concepts](https://php-di.org/doc/understanding-di.html), the benefits of the code above may be unclear to you. We could replace `$container->get` with `new MyClass()` and it would work perfectly. However, the container is a powerful tool, especially for more complex cases.&#x20;

You won't see a significant benefit if your `MyClass` has no dependencies. But let's say the class has 2-3 constructor arguments (e.g., a logger and a theme object). To get the `MyClass` instance, you would need to create those instances initially. Furthermore, one of those arguments may have its own arguments, and your creation code will turn into a multi-line creation.

{% hint style="info" %}
With PHP-DI, you don't need to worry about the constructor, as PHP-DI will use [PHP's reflection feature](https://www.php.net/manual/en/intro.reflection.php) to get the necessary instances and pass them to the constructor on the fly.
{% endhint %}

An additional benefit is that the `->get` method, [unlike](https://php-di.org/doc/container.html) `->make`, creates the instance only once, reusing it for other calls. This way, you get a smart 'global' variables pool, allowing you to handle dependencies easily and efficiently.&#x20;

{% hint style="info" %}
Unlike the [singleton pattern](https://en.wikipedia.org/wiki/Singleton_pattern), which is [considered an anti-pattern](https://medium.com/@razu.dev/singleton-the-anti-pattern-18fb2bd102c2), it doesn't turn your code into single-instance classes. You still define constructors, clearly specifying class dependencies, while avoiding the hassle of manual creation.
{% endhint %}

Additionally, PHP-DI supports and encourages the use of interfaces, so you can call&#x20;

`->get(MapInterface::class)->calculate()` in your code, while defining which exact class should be used for each interface in the container configuration.