prepareFilename example

$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.     $lock_id = $this->generateLockIdFromFileUri($file_uri);

    

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();

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

    

    else {
      $max_dimensions = 0;
    }

    $validators = [
      'file_validate_extensions' => ['gif png jpg jpeg'],
      'file_validate_size' => [$max_filesize],
      'file_validate_image_resolution' => [$max_dimensions],
    ];

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

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

    // Using the UploadedFile method instead of streamUploadData.     $temp_file_path = $upload->getRealPath();

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

    // Lock based on the prepared file URI.     $lock_id = $this->generateLockIdFromFileUri($file_uri);