如何在codeigniter中获取按钮点击对应文本区的值？

<form method="post" action="<?php echo site_url('controller/process_form'); ?>">
  <textarea name="text_area"></textarea>
  <input type="submit" name="submit_button" value="Submit">
</form>

class Controller extends CI_Controller {
  public function process_form() {
    // 验证和过滤用户输入
    $this->form_validation->set_rules('text_area', 'Text Area', 'required');

    if ($this->form_validation->run() == FALSE) {
      // 表单验证失败，显示错误信息或重新加载表单
    } else {
      // 获取按钮点击对应文本区的值
      $text_area_value = $this->input->post('text_area');

      // 在视图文件中显示或进行其他操作
      $data['text_area_value'] = $text_area_value;
      $this->load->view('result_view', $data);
    }
  }
}

<p>按钮点击对应文本区的值：<?php echo $text_area_value; ?></p>