code: public function textarea($options = [])
      {
          $options = array_merge($this->inputOptions, $options);
  
          if ($this->form->validationStateOn === ActiveForm::VALIDATION_STATE_ON_INPUT) {
              $this->addErrorClassIfNeeded($options);
          }
  
          $this->addAriaAttributes($options);
          $this->adjustLabelFor($options);
          $this->parts['{input}'] = Html::activeTextarea($this->model, $this->attribute, $options);
  
          return $this;
      }
docs: Renders a text area.
  The model attribute value will be used as the content in the textarea.
  @param array $options the tag options in terms of name-value pairs. These will be rendered as
  the attributes of the resulting tag. The values will be HTML-encoded using [[Html::encode()]].
  
  If you set a custom `id` for the textarea element, you may need to adjust the [[$selectors]] accordingly.
  
  @return $this the field object itself.