How do I programmatically create a file and write it in the private:// folder?

Question

How do I programmatically create a text file and write to it in the private:// folder in Drupal 8.8? I found some examples, but all of them use deprecated functions and they don't work.

Here what I have now, but i't s not creating folder and text file in it with content:

use Drupal\Core\StreamWrapper\PrivateStream;
...
...
$output = 'Test Text';
$file_save_path_stream_directory =  'private://gmt';

file_prepare_directory($file_save_path_stream_directory, FILE_CREATE_DIRECTORY | FILE_MODIFY_PERMISSIONS);

$fileLocation = $file_save_path_stream_directory . '/test.txt';

$file = file_save_data($output, $fileLocation, FILE_EXISTS_REPLACE);  

Answer 1

This answer is tested with Drupal 9.3 and doesn't use file_save_data(), which is deprecated in 9.3 and will be removed in Drupal 10.

use Drupal\Core\File\FileSystemInterface;

...

  /**
   * Provides helpers to operate on files and stream wrappers.
   *
   * @var \Drupal\Core\File\FileSystemInterface
   */
  protected $fileSystem;

  /**
   * Constructs an object.
   *
   * @param \Drupal\Core\File\FileSystemInterface $file_system
   *   The file system manager.
   */
  public function __construct(FileSystemInterface $file_system) {
    $this->fileSystem = $file_system;
  }

  public function testFunction($data, $destination) {
    if (!$this->fileSystem->prepareDirectory($destination, FileSystemInterface::CREATE_DIRECTORY)) {
      // @todo Log an error.
      return FALSE;
    }

    $this->fileSystem->saveData($data, $destination, FileSystemInterface::EXISTS_REPLACE);

    // Create and save a new file entity.
    // @see FileRepository::createOrUpdate().
    $new_file = File::create(['uri' => $file->uri]);
    $new_file->setOwnerId(1);
    $new_file->setPermanent();
    $new_file->save();

    return $new_file;
  }

It should also be noted that in Drupal 9.3, though $data can be a file handle resource passed to fileSystem->saveData(), it is not documented and doesn't have test coverage. file_save_data() also allowed a resource data parameter. FileRepository::writeData() does not allow one, however, although that's only because it specifies string $data in the function declaration.

Answer 2

As noted, file_save_data is deprecated as of Drupal 9.3. The file.repository service is a good replacement as it will both generate the actual file in the filesystem and the File entity.

<?php
use Drupal\Core\File\FileSystemInterface;

...

/**
 * @var \Drupal\Core\File\FileSystemInterface
 */
protected $fileSystem;


public function __construct(FileSystemInterface $fileSystem) {
    $this->fileSystem = $fileSystem;
}

public function testCreation() {
    $data = 'test content';
    $path = 'private://gmt/';
    $filename = 'requests.txt';
    if (!$this->fileSystem->prepareDirectory($destination, FileSystemInterface::CREATE_DIRECTORY)) {
        // @todo Log an error.
        return FALSE;
    }
    
    // this will both create the actual file and the File entity. Returns the entity.
    $file = \Drupal::service('file.repository')->writeData($data, $path.$filename);

    // here's the fid to reference elsewhere
    $fid = $file->id();

 
}

Answer 3

If anyone need it, I make it work:

use Drupal\Core\File\FileSystemInterface;

...

  /**
   * @var \Drupal\Core\File\FileSystemInterface
   */
  protected $fileSystem;


  public function __construct(FileSystemInterface $fileSystem) {
    $this->fileSystem = $fileSystem;
  }

  public function testCreation() {
    $request = 'test content';
    $path = 'private://gmt/';
    if ($this->fileSystem->prepareDirectory($path, FileSystemInterface::CREATE_DIRECTORY)) {
      /** @var \Drupal\file\FileInterface $file */
      $file = file_save_data(
        $request,
        $path . 'requests.txt'
      );
    }
  }