stream_filter_register - PHP code example

The php Function Stream_Filter_Register

Streams are a fundamental part of the PHP language. They are used for everything from moving files around a network to reading and writing data line by line.

Using streams lets you do many things, but one thing that people tend to overlook is the power of filtering. With the php function stream_filter_register you can add your own custom filters to any stream.

The built in filters that come with PHP are very useful, but sometimes you need more specialized filtering. The php function stream_filter_register() allows you to register user designed wrappers that can be attached to any registered stream that is used with all of the filesystem functions like fopen(), fread() etc.

You will need to create a class that extends the php_user_filter and implement its methods as described in the manual page for stream_filter_register(). This class will need to have a constructor function and a method called onCreate(). The constructor function will need to pass the class object for which it is creating a filter for. The method onCreate() needs to return the filter's callback function if the constructor returned success or an error code if not.

The php function stream_filter_register() also has other methods. The prepend(resourcestream> $stream, callable $callback, int $read_write) function pre-appends a filter to the end of the list of filters that are attached to the given stream. The remove(resourcestream> $stream, bool $callback) function will remove the given filter from the list of filters that are attached to the stream.

stream_filter_register example

class UnitTestCaseTest extends UnitTestCase {

  /** * Tests the dump() function in a test run in the same process. */
  public function testVarDumpSameProcess() {
    // Append the stream capturer to the STDOUT stream, so that we can test the     // dump() output and also prevent it from actually outputting in this     // particular test.     stream_filter_register("capture", StreamCapturer::class);
    stream_filter_append(STDOUT, "capture");

    // Dump some variables.     $object = (object) [
      'foo' => 'bar',
    ];
    dump($object);
    dump('banana');

    $this->assertStringContainsString('bar', StreamCapturer::$cache);
    $this->assertStringContainsString('banana', StreamCapturer::$cache);
  }

\Drupal::service('extension.list.module')->getPathname('demo_umami_content')
    );
  }

  /** * Tests the dump() function provided by the var-dumper Symfony component. */
  public function testVarDump() {
    // Append the stream capturer to the STDOUT stream, so that we can test the     // dump() output and also prevent it from actually outputting in this     // particular test.     stream_filter_register("capture", StreamCapturer::class);
    stream_filter_append(STDOUT, "capture");

    // Dump some variables.     $this->enableModules(['system', 'user']);
    $role = Role::create(['id' => 'test_role', 'label' => 'Test role']);
    dump($role);
    dump($role->id());

    $this->assertStringContainsString('Drupal\user\Entity\Role', StreamCapturer::$cache);
    $this->assertStringContainsString('test_role', StreamCapturer::$cache);
  }

static::$buffer .= $bucket->data;

            $consumed += $bucket->datalen;
        }

        return PSFS_PASS_ON;
    }

    public static function registration(): void
    {
        if (! static::$registered) {
            static::$registered = stream_filter_register('CITestStreamFilter', self::class); // @codeCoverageIgnore         }

        static::$buffer = '';
    }

    public static function addErrorFilter(): void
    {
        self::removeFilter(self::$err);
        self::$err = stream_filter_append(STDERR, 'CITestStreamFilter');
    }

    $this->assertCount(1, $test_deprecation_messages);
  }

  /** * Tests the dump() function provided by the var-dumper Symfony component. */
  public function testVarDump() {
    // Append the stream capturer to the STDOUT stream, so that we can test the     // dump() output and also prevent it from actually outputting in this     // particular test.     stream_filter_register("capture", StreamCapturer::class);
    stream_filter_append(STDOUT, "capture");

    // Dump some variables to check that dump() in test code produces output     // on the command line that is running the test.     $role = Role::load('authenticated');
    dump($role);
    dump($role->id());

    $this->assertStringContainsString('Drupal\user\Entity\Role', StreamCapturer::$cache);
    $this->assertStringContainsString('authenticated', StreamCapturer::$cache);