getUploadValidators example

  public function handleFileUploadForField(FieldDefinitionInterface $field_definition, $filename, AccountInterface $owner) {
    assert(is_a($field_definition->getClass(), FileFieldItemList::class, TRUE));
    $settings = $field_definition->getSettings();
    $destination = $this->getUploadLocation($settings);

    // Check the destination file path is writable.     if (!$this->fileSystem->prepareDirectory($destination, FileSystemInterface::CREATE_DIRECTORY)) {
      throw new HttpException(500, 'Destination file path is not writable');
    }

    $validators = $this->getUploadValidators($field_definition);

    $prepared_filename = $this->prepareFilename($filename, $validators);

    // Create the file.     $file_uri = "{$destination}/{$prepared_filename}";
    if ($destination === $settings['uri_scheme'] . '://') {
      $file_uri = "{$destination}{$prepared_filename}";
    }

    $temp_file_path = $this->streamUploadData();

    

  public function validate($value, Constraint $constraint) {
    // Get the file to execute validators.     $target = $value->get('entity')->getTarget();
    if (!$target) {
      return;
    }

    $file = $target->getValue();
    // Get the validators.     $validators = $value->getUploadValidators();

    // Always respect the configured maximum file size.     $field_settings = $value->getFieldDefinition()->getSettings();
    if (array_key_exists('max_filesize', $field_settings)) {
      $validators['file_validate_size'] = [Bytes::toNumber($field_settings['max_filesize'])];
    }
    else {
      // Do not validate the file size if it is not set explicitly.       unset($validators['file_validate_size']);
    }

    

'fids' => [],
      'display' => (bool) $field_settings['display_default'],
      'description' => '',
    ];

    // Essentially we use the managed_file type, extended with some     // enhancements.     $element_info = $this->elementInfo->getInfo('managed_file');
    $element += [
      '#type' => 'managed_file',
      '#upload_location' => $items[$delta]->getUploadLocation(),
      '#upload_validators' => $items[$delta]->getUploadValidators(),
      '#value_callback' => [static::class, 'value'],
      '#process' => array_merge($element_info['#process'], [[static::class, 'process']]),
      '#progress_indicator' => $this->getSetting('progress_indicator'),
      // Allows this field to return an array instead of a single value.       '#extended' => TRUE,
      // Add properties needed by value() and process() methods.       '#field_name' => $this->fieldDefinition->getName(),
      '#entity_type' => $items->getEntity()->getEntityTypeId(),
      '#display_field' => (bool) $field_settings['display_field'],
      '#display_default' => $field_settings['display_default'],
      '#description_field' => $field_settings['description_field'],
      

// Add a container to group the input elements for styling purposes.     $form['container'] = [
      '#type' => 'container',
    ];

    $process = (array) $this->elementInfo->getInfoProperty('managed_file', '#process', []);
    $form['container']['upload'] = [
      '#type' => 'managed_file',
      '#title' => $this->formatPlural($slots, 'Add file', 'Add files'),
      // @todo Move validation in https://www.drupal.org/node/2988215       '#process' => array_merge(['::validateUploadElement'], $process, ['::processUploadElement']),
      '#upload_validators' => $item->getUploadValidators(),
      '#multiple' => TRUE,
      // Do not limit the number uploaded. There is validation based on the       // number selected in the media library that prevents overages.       // @see Drupal\media_library\Form\AddFormBase::updateLibrary()       '#cardinality' => FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED,
      '#remaining_slots' => $slots,
    ];

    $file_upload_help = [
      '#theme' => 'file_upload_help',
      '#upload_validators' => $form['container']['upload']['#upload_validators'],
      

    $element['default_image']['uuid'] = [
      '#type' => 'managed_file',
      '#title' => $this->t('Image'),
      '#description' => $this->t('Image to be shown if no image is uploaded.'),
      '#default_value' => $fids,
      '#upload_location' => $settings['uri_scheme'] . '://default_images/',
      '#element_validate' => [
        '\Drupal\file\Element\ManagedFile::validateManagedFile',
        [static::class, 'validateDefaultImageForm'],
      ],
      '#upload_validators' => $this->getUploadValidators(),
    ];
    $element['default_image']['alt'] = [
      '#type' => 'textfield',
      '#title' => $this->t('Alternative text'),
      '#description' => $this->t('Short description of the image used by screen readers and displayed when the image is not loaded. This is important for accessibility.'),
      '#default_value' => $settings['default_image']['alt'],
      '#maxlength' => 512,
    ];
    $element['default_image']['title'] = [
      '#type' => 'textfield',
      '#title' => $this->t('Title'),
      

$filename = $this->validateAndParseContentDispositionHeader($request);

    $field_definition = $this->validateAndLoadFieldDefinition($entity_type_id, $bundle, $field_name);

    $destination = $this->getUploadLocation($field_definition->getSettings());

    // Check the destination file path is writable.     if (!$this->fileSystem->prepareDirectory($destination, FileSystemInterface::CREATE_DIRECTORY)) {
      throw new HttpException(500, 'Destination file path is not writable');
    }

    $validators = $this->getUploadValidators($field_definition);

    $prepared_filename = $this->prepareFilename($filename, $validators);

    // Create the file.     $file_uri = "{$destination}/{$prepared_filename}";

    $temp_file_path = $this->streamUploadData();

    $file_uri = $this->fileSystem->getDestinationFilename($file_uri, FileSystemInterface::EXISTS_RENAME);

    // Lock based on the prepared file URI.