只顯示某一分類文章

PHP8入門

6-1 只顯示某一分類文章

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;

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;

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];
}