Issue #3285560 by Anybody, thomas.frobieter: Add a "Create Slideshow"-Link to...

    }

  }

}

/**

 * Implements hook_field_widget_media_library_widget_form_alter().

 *

 * Adds a "Create new Slideshow" button beneath "Select slideshow" media library

 * widget button. This is a *workaround* to provide a link for slideshow creation

 * as "Slideshow" is a custom media source, which doesn't provide a create itself.

 */

function drowl_media_field_widget_media_library_widget_form_alter(&$element, \Drupal\Core\Form\FormStateInterface $form_state, $context) {

  if (!empty($element['#target_bundles']) && in_array("slideshow", $element['#target_bundles'])) {

    // Change the regular "Add"-label, so its clear to the user that this means

    // "Reference to existing Slideshows"

    $element["open_button"]["#value"] = t('Select Slideshow');

    // Add further "Create Slideshow"-Button, opens the Slideshow create form in a new tab

    $element['#field_suffix']['empty_selection'] = [

      '#type' => 'link',

      '#title' => t('Create new Slideshow'),

      '#url' => \Drupal\Core\Url::fromRoute('entity.media.add_form', ['media_type' => 'slideshow']),

      '#attributes' => [

        'target' => '_blank',

        'class' => ['button', 'primary'],

        // Preparation to open the dialog in a modal, but as we can not

        // simply set the created slideshow, we didn't proceed here yet:

        // 'class' => ['button', 'primary', 'use-ajax'],

        // 'data-dialog-type' => 'modal',

        // 'data-dialog-options' => '{width: 90%, height: 80%}',

      ],

      '#weight' => 99,

    ];

  }

}