Question

我有一个PDO数据库连接类，我在整个网站上使用它。

pdoConnect.php

class pdoConnect {
    private $host = "localhost";
    private $db = "database";
    private $userSelect = "user";
    private $passSelect = "XXXXX";
    protected $selectInstance = true;
    protected $options = [
        PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8',
        PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
        PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC
    ];

    function dsn() {
        return 'mysql:host=' . $this->host . ';dbname=' . $this->db;
    }

    function connectSelect() {
        if ($this->selectInstance === true) {
            $dsn = $this->dsn();
            $this->selectConnect = new PDO($dsn, $this->userSelect, $this->passSelect, 
                                           $this->options);
        }
        return $this->selectConnect;
    }
}

pagination.php

class pagination {
    var $php_self;
    var $rows_per_page = 10; //Number of records to display per page
    var $total_rows = 0; //Total number of rows returned by the query
    var $links_per_page = 5; //Number of links to display per page
    var $append = ""; //Parameters to append to pagination links
    var $sql = "";
    var $debug = false;
    var $conn = false;
    var $page = 1;
    var $max_pages = 0;
    var $offset = 0;
    var $multi = ""; //Use if multiple pagination instances are needed

    function pagination($connection, $sql, $rows_per_page = 10, 
                        $links_per_page = 5, $append = "", $multi = "") {

        $this->conn = $connection;
        $this->sql = $sql;
        $this->rows_per_page = (int)$rows_per_page;
        if (intval($links_per_page ) > 0) {
            $this->links_per_page = (int)$links_per_page;
        } else {
            $this->links_per_page = 5;
        }

        $this->append = $append;
        $this->multi = $multi;

        $this->php_self = htmlspecialchars($_SERVER['PHP_SELF'] );
        if (isset($_GET['page'] )) {
            $this->page = intval($_GET['page'] );
        }
    }

    function paginate(){

            if ($this->sql != null) {
                $all_rs = $this->conn->query($this->sql); //this is line 76
                $this->total_rows = $all_rs->rowCount();
            }

            ....
    }
}

它可以在其他任何地方正常工作，但是，如果我实例化它，那么将它作为参数传递给另一个类，该对象不可访问。

require_once '/classes/pdoConnect.php';
$db = new pdoConnect();
$pdo = $db->connectSelect();

require_once '/classes/pagination.php';
$pages = new pagination( $pdo, $sql, $page_amount, 8, null );

然后我得到......

致命错误：在非对象中调用成员函数query（）第76行/classes/pagination.php

但是PDO连接对象存在！

var_dump($pdo);
object(PDO)#1 (0) { }

我唯一能想到的是，我已将pdoConnect类扩展到另一个类，以便访问$selectInstance属性。所以在我的IDE中，pdoConnect类说is Overridden。有人可以告诉我这里发生了什么吗？

Answer 1

尝试更改function pagination( to function __construct(

__construct和__destruct是在实例化或销毁对象时随时调用（幕后）的特殊方法。如果要将参数作为对象实例化的一部分传递，则需要通过__construct方法执行此操作。另一种方法是使用访问器：

$pages = new pagination;

$pages->setConn($pdo);
$pages->setSql($sql);
$pages->setRowsPerPage($page_amount);
....

您的pagination函数不是访问者，它是一种用于以特定方式执行逻辑的包装器方法。访问者只是getters和setters的一个奇特术语。请考虑以下事项：

class Pagination
{
    $conn = false; // This is a member variable
}

通常，您不希望允许外部代码直接设置类的成员变量的值，否则会破坏封装。相反，你想使用一个访问器，如下所示：

// somescript.php
$pager = new Pagination;

$pager->conn = $pdo; // Not a good practice

$pager->setConnection($pdo); // Setting the member variable through an accessor, preferred

PHP类对象在另一个类中无法访问？

1 个答案: