Codeigniter Undefined Index 网上商店

问：

Codeigniter Undefined Index 网上商店：

出于某种原因，我得到了“未定义的索引：控制器中的分组。

我在下面添加了控制器和模型。

我也刚刚添加了getProduct（）代码

/*Here is my model*/
  function getProductsByGroup($limit,$group,$skip){
     $data = array();
     if ($limit == 0){
        $limit=3;
     }
     $this->db->select('id,name,shortdesc,thumbnail');
     $this->db->where('grouping', $group);
     $this->db->where('status', 'active');
     $this->db->where('id !=', ($skip));
     $this->db->order_by('name','asc');
     $this->db->limit($limit);
     $Q = $this->db->get('products');
     if ($Q->num_rows() > 0){
       foreach ($Q->result_array() as $row){
         $data[] = $row;
       }
    }
    $Q->free_result();    
    return $data; 
 }  

/*getProduct()*/
function getProduct($id){

        $data = array();
        $option = array('id' => $id);
        /*pass the id and other options to the category*/
        $Q = $this->db->get_where("categories",$option,1);
        if ($Q ->num_rows() > 0){
            $data = $Q->row_array();
        }
        $Q->free_result();
        return $data;
    }


/*This is my controller*/
    public function product($id)
    {
        $product = $this->MProducts->getProduct($id); 

        if (!count($product))
        {
        redirect('welcome/index','refresh'); 
        }

/* This is where the error is coming from*/
        $data['grouplist'] =  $this->MProducts->getProductsByGroup(3,$product['grouping'],$id);
        $data['product'] = $product;
        $data['title'] = "Claudia’s Kids | ". $product['name']; 
        $data['main'] = 'product';
        $data['navlist'] = $this->MCats->getCategoriesNav(); 
        $this->load->vars($data); 
        $this->load->view('template');
    }