class FilterNull

Same name and namespace in other branches
  1. 8.9.x core/modules/filter/src/Plugin/Filter/FilterNull.php \Drupal\filter\Plugin\Filter\FilterNull
  2. 10 core/modules/filter/src/Plugin/Filter/FilterNull.php \Drupal\filter\Plugin\Filter\FilterNull
  3. 11.x core/modules/filter/src/Plugin/Filter/FilterNull.php \Drupal\filter\Plugin\Filter\FilterNull

Provides a fallback placeholder filter to use for missing filters.

The filter system uses this filter to replace missing filters (for example, if a filter module has been disabled) that are still part of defined text formats. It returns an empty string.

Plugin annotation

  id = "filter_null",
  title = @Translation("Provides a fallback for missing filters. Do not use."),
  type = Drupal\filter\Plugin\FilterInterface::TYPE_HTML_RESTRICTOR,
  weight = -10


Expanded class hierarchy of FilterNull

1 file declares its use of FilterNull
FilterFormatFormBase.php in core/modules/filter/src/FilterFormatFormBase.php


core/modules/filter/src/Plugin/Filter/FilterNull.php, line 22


View source
class FilterNull extends FilterBase {
     * Tracks if an alert about this filter has been logged.
     * @var bool
    protected $logged = FALSE;
     * {@inheritdoc}
    public function __construct(array $configuration, $plugin_id, $plugin_definition) {
        // Once per filter, log that a filter plugin was missing.
        if (!$this->logged) {
            $this->logged = TRUE;
            \Drupal::logger('filter')->alert('Missing filter plugin: %filter.', [
                '%filter' => $plugin_id,
        parent::__construct($configuration, $plugin_id, $plugin_definition);
     * {@inheritdoc}
    public function process($text, $langcode) {
        return new FilterProcessResult('');
     * {@inheritdoc}
    public function getHTMLRestrictions() {
        // Nothing is allowed.
        return [
            'allowed' => [],
     * {@inheritdoc}
    public function tips($long = FALSE) {
        return $this->t('Missing filter. All text is removed');



Title Sort descending Modifiers Object type Summary Overriden Title Overrides
FilterBase::$provider public property The name of the provider that owns this filter.
FilterBase::$settings public property An associative array containing the configured settings of this filter.
FilterBase::$status public property A Boolean indicating whether this filter is enabled.
FilterBase::$weight public property The weight of this filter compared to others in a filter collection.
FilterBase::calculateDependencies public function Calculates dependencies for the configured plugin. Overrides DependentPluginInterface::calculateDependencies 1
FilterBase::defaultConfiguration public function Gets default configuration for this plugin. Overrides ConfigurableInterface::defaultConfiguration
FilterBase::getConfiguration public function Gets this plugin's configuration. Overrides ConfigurableInterface::getConfiguration
FilterBase::getDescription public function Returns the administrative description for this filter plugin. Overrides FilterInterface::getDescription
FilterBase::getLabel public function Returns the administrative label for this filter plugin. Overrides FilterInterface::getLabel
FilterBase::getType public function Returns the processing type of this filter plugin. Overrides FilterInterface::getType
FilterBase::prepare public function Prepares the text for processing. Overrides FilterInterface::prepare
FilterBase::setConfiguration public function Sets the configuration for this plugin instance. Overrides ConfigurableInterface::setConfiguration 1
FilterBase::settingsForm public function Generates a filter's settings form. Overrides FilterInterface::settingsForm 3
FilterInterface::TYPE_HTML_RESTRICTOR constant HTML tag and attribute restricting filters to prevent XSS attacks.
FilterInterface::TYPE_MARKUP_LANGUAGE constant Non-HTML markup language filters that generate HTML.
FilterInterface::TYPE_TRANSFORM_IRREVERSIBLE constant Irreversible transformation filters.
FilterInterface::TYPE_TRANSFORM_REVERSIBLE constant Reversible transformation filters.
FilterNull::$logged protected property Tracks if an alert about this filter has been logged.
FilterNull::getHTMLRestrictions public function Returns HTML allowed by this filter's configuration. Overrides FilterBase::getHTMLRestrictions
FilterNull::process public function Performs the filter processing. Overrides FilterInterface::process
FilterNull::tips public function Generates a filter's tip. Overrides FilterBase::tips
FilterNull::__construct public function Overrides FilterBase::__construct
PluginInspectionInterface::getPluginDefinition public function Gets the definition of the plugin implementation. 6
PluginInspectionInterface::getPluginId public function Gets the plugin_id of the plugin instance. 2

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