How do I save uploaded file permanently in file_manged table?

Question

How do I save a uploaded file with status equal to 1 in the file_managed table, in Drupal 8?

Whenever I upload a file, it is stored in the file_managed table with status value 0.
I have used File::load( $form_state->getValue('image')) to load the file. What do I need to do next?

In Drupal 7, I would use $file->status = FILE_STATUS_PERMANENT. What is the equivalent code for Drupal 8?

class AddBannerForm extends FormBase {
  
  public function getFormId() {
    return 'add_banner_form';
  }

  public function buildForm(array $form, FormStateInterface $form_state) {
    $form['image'] = [
      '#type' => 'managed_file',
      '#title' => t('Choose Image File'),
      '#upload_location' => 'public://images/',
      '#default_value' => '',
      '#description' => t('Specify an image(s) to display.'),
      '#states' => [
        'visible' => [
          ':input[name="image_type"]' => ['value' => t('Upload New Image(s)')],
        ],
      ],
    ];

    $form['submit'] = [
      '#type' => 'submit',
      '#value' => t('Save image'),
    ];

    return $form;
  }


  public function validateForm(array &$form, FormStateInterface $form_state) {
    File::load($form_state->getValue('image'));
  }


  public function submitForm(array &$form, FormStateInterface $form_state) {

  }
}

Answer 1

Thank you @Clive & @kiamlaluno

/* Fetch the array of the file stored temporarily in database */ 
   $image = $form_state->getValue('image');

/* Load the object of the file by it's fid */ 
   $file = File::load( $image[0] );

/* Set the status flag permanent of the file object */
   $file->setPermanent();

/* Save the file in database */
   $file->save();

Answer 2

Use this code to save the image permanently in the configuration form, if you are using Drupal 8.

public function submitForm(array &$form, FormStateInterface $form_state) {
  parent::submitForm($form, $form_state);
  $image = $form_state->getValue('welcome_image');
  // Load the object of the file by its fid. 
  $file = File::load($image[0]);
  // Set the status flag permanent of the file object.
  if (!empty($file)) {
    $file->setPermanent();
    // Save the file in the database.
    $file->save();
    $file_usage = \Drupal::service('file.usage'); 
    $file_usage->add($file, 'welcome', 'welcome', \Drupal::currentUser()->id());
  }
  $config = $this->config('welcome.settings');
  $config->set('welcome_text', $form_state->getValue('welcome_text'))
    ->set('welcome_image', $form_state->getValue('welcome_image'))
    ->save();
}

Answer 3

You might also need to disable cache in your buildForm function

$form_state->disableCache();