protected function renderFilterCellContent()
 {
     if (is_string($this->filter)) {
         return $this->filter;
     }
     $model = $this->grid->filterModel;
     if ($this->filter !== false && $model instanceof Model && $this->attribute !== null && $model->isAttributeActive($this->attribute)) {
         if ($model->hasErrors($this->attribute && $this->enableError == true)) {
             $error = Html::error($model, $this->attribute, $this->grid->filterErrorOptions);
         } else {
             $error = '';
         }
         if (is_array($this->filter)) {
             $options = array_merge(['prompt' => ''], $this->filterDropdownOptions);
             if ($model->hasErrors($this->attribute) && $this->enableError == true) {
                 UI::addCssClasses($options, ['error']);
             }
             return Select::widget(['model' => $model, 'attribute' => $this->attribute, 'items' => $this->filter, 'options' => $options, 'search' => true]) . ' ' . $error;
         } else {
             $options = ['class' => 'fluid'];
             if ($model->hasErrors($this->attribute) && $this->enableError == true) {
                 UI::addCssClasses($options, ['error']);
             }
             return UI::inputWraper(Html::activeTextInput($model, $this->attribute, $this->filterInputOptions) . $error, $options);
         }
     } else {
         return parent::renderFilterCellContent();
     }
 }