Issue #3231861 by Lendude, GuyPaddock: PHP errors when overriding the query settings

   */

  public function submitOptionsForm(&$form, FormStateInterface $form_state) {

    $element = ['#parents' => ['query', 'options', 'query_tags']];

    $value = explode(',', NestedArray::getValue($form_state->getValues(), $element['#parents']));

    $value = array_filter(array_map('trim', $value));

    $value = NestedArray::getValue($form_state->getValues(), $element['#parents']);

    // When toggling a display to override defaults or vice-versa the submit

    // handler gets invoked twice, and we don't want to bash the values from the

    // original call.

    if (is_array($value)) {

      return;

    }

    $value = array_filter(array_map('trim', explode(',', $value)));

    $form_state->setValueForElement($element, $value);

  }

<?php

namespace Drupal\Tests\views\Functional\Plugin;

use Drupal\Tests\views\Functional\ViewTestBase;

/**

 * Tests setting the query options.

 *

 * @group views

 */

class QueryOptionsTest extends ViewTestBase {

  /**

   * Views used by this test.

   *

   * @var array

   */

  public static $testViews = ['test_view'];

  /**

   * Modules to enable.

   *

   * @var array

   */

  protected static $modules = ['node', 'views_ui'];

  /**

   * {@inheritdoc}

   */

  protected $defaultTheme = 'stark';

  /**

   * Test that query overrides are stored.

   */

  public function testStoreQuerySettingsOverride() {

    // Show the default display so the override selection is shown.

    \Drupal::configFactory()->getEditable('views.settings')->set('ui.show.default_display', TRUE)->save();

    $admin_user = $this->drupalCreateUser([

      'administer views',

      'administer site configuration',

    ]);

    $this->drupalLogin($admin_user);

    $edit = [];

    $this->drupalGet('admin/structure/views/view/test_view/edit');

    $this->submitForm($edit, 'Add Page');

    $this->drupalGet('admin/structure/views/nojs/display/test_view/page_1/query');

    $this->assertSession()->checkboxNotChecked('query[options][distinct]');

    $edit = [

      'override[dropdown]' => 'page_1',

      'query[options][distinct]' => 1,

    ];

    $this->submitForm($edit, 'Apply');

    $this->drupalGet('admin/structure/views/nojs/display/test_view/page_1/query');

    $this->assertSession()->checkboxChecked('query[options][distinct]');

    $edit = [

      'query[options][query_comment]' => 'comment',

      'query[options][query_tags]' => 'query_tag, another_tag',

    ];

    $this->submitForm($edit, 'Apply');

    $this->drupalGet('admin/structure/views/nojs/display/test_view/page_1/query');

    $this->assertSession()->checkboxChecked('query[options][distinct]');

    $this->assertSession()->fieldValueEquals('query[options][query_comment]', 'comment');

    $this->assertSession()->fieldValueEquals('query[options][query_tags]', 'query_tag, another_tag');

  }

}