Listener

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The listener layout is used when it is necessary to change the displayed data, in accordance with the selected user settings.

For example, we have a screen on which there are two fields for entering numbers. We need to display the third field, the value of which will be the sum of the other two:

namespace App\Orchid\Screens;

use Orchid\Screen\Action;
use Orchid\Screen\Fields\Input;
use Orchid\Support\Facades\Layout;
use Orchid\Screen\Screen;

class PlatformScreen extends Screen
{
    /**
     * Query data.
     *
     * @return array
     */
    public function query(): array
    {
        return [];
    }

    /**
     * Display header name.
     *
     * @return string
     */
    public function name(): ?string
    {
        return 'Dashboard';
    }

    /**
     * Button commands.
     *
     * @return Action[]
     */
    public function commandBar(): array
    {
        return [];
    }

    /**
     * Views.
     *
     * @return Layout[]
     */
    public function layout(): array
    {
        return [
            Layout::rows([
                Input::make('a')
                    ->title('First argument')
                    ->type('number'),

                Input::make('b')
                    ->title('Second argument')
                    ->type('number'),
            ]),
        ];
    }
}

To create a listener layout, run the artisan command:

php artisan orchid:listener AmountListener

In the directory app/Orchid/Layouts a new class will be created with the name AmountListener:

namespace App\Orchid\Layouts;

use Orchid\Screen\Fields\Input;
use Orchid\Support\Facades\Layout;
use Orchid\Screen\Layouts\Listener;

class AmountListener extends Listener
{
    /**
     * List of field names for which values will be listened.
     *
     * @var string[]
     */
    protected $targets = [];

    /**
     * What screen method should be called
     * as a source for an asynchronous request.
     *
     * The name of the method must
     * begin with the prefix "async"
     *
     * @var string
     */
    protected $asyncMethod = '';

    /**
     * @return Layout[]
     */
    protected function layouts(): array
    {
        return [
            Layout::rows([
                Input::make('a')
                    ->title('First argument')
                    ->type('number'),

                Input::make('b')
                    ->title('Second argument')
                    ->type('number'),
            ]),
        ];
    }
}

The targets property specifies the names of the fields, when changed, the required action will be performed. For our example, these are the fields with the names a and b:

/**
 * List of field names for which values will be listened.
 *
 * @var string[]
 */
protected $targets = [
    'a',
    'b',
];

Note. Multiple choice fields such as <select name="users[]"> need to indicate that they are an array by ending the target value with a dot, such as "users."

The asyncMethod property must specify the method that will be called when the fields are changed. This method must be implemented on the screen. Add it with the name asyncSum:

namespace App\Orchid\Screens;

use App\Orchid\Layouts\AmountListener;
use Orchid\Screen\Action;
use Orchid\Screen\Fields\Input;
use Orchid\Support\Facades\Layout;
use Orchid\Screen\Screen;

class PlatformScreen extends Screen
{
    /**
     * Query data.
     *
     * @return array
     */
    public function query(): array
    {
        return [];
    }

    /**
     * Display header name.
     *
     * @return string
     */
    public function name(): ?string
    {
        return 'Dashboard';
    }

    /**
     * Button commands.
     *
     * @return Action[]
     */
    public function commandBar(): array
    {
        return [];
    }

    /**
     * @param int|null $a
     * @param int|null $b
     *
     * @return string[]
     */
    public function asyncSum(int $a = null, int $b = null)
    {
        return [
            'a' => $a,
            'b' => $b,
            'sum' => $a + $b,
        ];
    }

    /**
     * Views.
     *
     * @return Layout[]
     */
    public function layout(): array
    {
        return [
            AmountListener::class,
        ];
    }
}

Please note. Such a function is a substitute for the query for the required layouts, and the async prefix is required.

And indicate its name:

/**
 * What screen method should be called
 * as a source for an asynchronous request.
 *
 * The name of the method must
 * begin with the prefix "async"
 *
 * @var string
 */
protected $asyncMethod = 'asyncSum';

It remains only to determine what will be shown in this layer. The full class will look like this:

namespace App\Orchid\Layouts;

use Orchid\Screen\Fields\Input;
use Orchid\Support\Facades\Layout;
use Orchid\Screen\Layouts\Listener;

class AmountListener extends Listener
{
    /**
     * List of field names for which values will be listened.
     *
     * @var string[]
     */
    protected $targets = [
        'a',
        'b',
    ];

    /**
     * What screen method should be called
     * as a source for an asynchronous request.
     *
     * The name of the method must
     * begin with the prefix "async"
     *
     * @var string
     */
    protected $asyncMethod = 'asyncSum';

    /**
     * @return Layout[]
     */
    protected function layouts(): array
    {
        return [
            Layout::rows([
                Input::make('a')
                    ->title('First argument')
                    ->type('number'),

                Input::make('b')
                    ->title('Second argument')
                    ->type('number'),

                Input::make('sum')
                    ->readonly()
                    ->canSee($this->query->has('sum')),
            ]),
        ];
    }
}

Now, when changing the values of the input fields, the sum field will change automatically.