6-1 只顯示某一分類文章

1. 為了讓文章可以篩選，我們修改 index.php，先進行 $category 的變數過濾，並將 $category 作為新參數，以便在函數中可以根據該值來篩選文章。

   // 變數過濾
   $id = isset($_REQUEST['id']) ? (int) $_REQUEST['id'] : 0;
   $op = isset($_REQUEST['op']) ? htmlspecialchars($_REQUEST['op']) : 'index';
   $category = isset($_REQUEST['category']) ? (int) $_REQUEST['category'] : 0;

    

2. 流程部份也要加進去該參數，才能針對某一分類取得新聞或計算文章數量（必填的參數放前面）

   // 預設為文章列表
   default:
       list($all_news, $paginator) = index($category, $perPage);
       $smarty->assign('all_news', $all_news);
       $smarty->assign('paginator', $paginator);
       break;

    

3. 修改 index() 函式，多加一個 $category 參數，需要判斷有無 $category 的值採取不同SQL語法

   // 列出所有文章
   function index($category = 0, $perPage = 10)
   {
       global $pdo;
       // 計算總資料數
       try {
           if ($category) {
               $stmt = $pdo->prepare('SELECT count(*) FROM `news` WHERE `category`=?');
               $stmt->execute([$category]);
           } else {
               $stmt = $pdo->prepare('SELECT count(*) FROM `news`');
               $stmt->execute();
           }
           list($totalCount) = $stmt->fetch(PDO::FETCH_NUM);
           // 產生分頁物件
           $pagination = new Pagination(['totalCount' => $totalCount, 'perPage' => $perPage]);
           // 產生分頁工具列
           ob_start();
           Paginator::widget(['pagination' => $pagination]);
           $paginator = ob_get_clean();
       } catch (PDOException $e) {
           die("計算總資料數失敗：" . $e->getMessage());
       }
   
       try {
           if ($category) {
               $stmt = $pdo->prepare('SELECT * FROM `news` WHERE `category`=? ORDER BY `date` DESC LIMIT ?, ?');
               $stmt->execute([$category, $pagination->offset, $pagination->limit]);
           } else {
               $stmt = $pdo->prepare('SELECT * FROM `news` ORDER BY `date` DESC LIMIT ?, ?');
               $stmt->execute([$pagination->offset, $pagination->limit]);
           }
           $all_news = [];
           $news = $stmt->fetchAll();
           foreach ($news as $row) {
               $media = $row['media'];
               unset($row['media']);
               $row = array_map('htmlspecialchars', $row);
               $row['files'] = json_decode($media, true);
               $all_news[] = $row;
           }
   
       } catch (PDOException $e) {
           echo "資料庫連接錯誤：" . $e->getMessage();
       }
       return [$all_news, $paginator];
   }

    

4. 如此，便能列出不同分類文章：