Question

我是PHP新手，我正在努力了解它是如何工作的。我正在尝试将PDO实现到我自己的类中。

这就是我在做的事情：

class db {

    private $options;

    function __construct() {
        $this->options = array(
            'database_host' => DATABASE_HOST,
            'database_name' => DATABASE_NAME,
            'database_user' => DATABASE_USER,
            'database_pass' => DATABASE_PASS
        );

    }

    private function connect() {
        try {
            $pdo = new PDO('mysql:host=' . $this->options['database_host'] . ';dbname=' . $this->options['database_name'], $this->options['database_user'], $this->options['database_pass']);
            $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
            $pdo->exec("set names utf8");
        } catch (PDOException $e) {
            echo 'ERROR: ' . $e->getMessage();
        }
    }

    public function select($table, $what, $where, $custom) {

        $query = "SELECT " . $what . " FROM " . $table;
        $child = "1";
        $param = array();
        if ($where)
            foreach ($where as $data => $value) {
                if ($child == "1") {
                    $query .= " WHERE " . $data . " = '" . $value . "'";
                    $param[":" . $data] = $value;
                    $child = "next";
                } else {
                    $query .= " AND " . $data . " = '" . $value . "'";
                    $param[":" . $data] = $value;
                }
            }

        if ($custom)
            $query .= ' ' . $custom;

        $statement = $pdo->prepare($query);
        if ($statement->execute($param))
            return $statement->fetchAll(PDO::FETCH_ASSOC);
        return false;
    }

}

问题在于我不知道如何使函数connect()与下面的select()进行通信当我尝试调用select()函数时，我收到此错误：

Fatal error: Call to a member function prepare() on a non-object in /Applications/MAMP/htdocs/game/api/class.db.php on line 47

我希望当我调用select()函数时，connect()连接到数据库并使其所有变量可用于该类的其他函数...但我迷失了。

Answer 1

将$pdo变量存储为属性。目前它只是connect()方法的本地变量。

class db {
    private $options;
    private $pdo;
}

然后使用$this->pdo从任何方法访问它。例如，在connect()：

中

private function connect() {
    try {
        $this->pdo = new PDO('mysql:host=' . $this->options['database_host'] . ';dbname=' . $this->options['database_name'], $this->options['database_user'], $this->options['database_pass']);
        $this->pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $this->pdo->exec("set names utf8");
    } catch (PDOException $e) {
        echo 'ERROR: ' . $e->getMessage();
    }
}

对其他方法也这样做，例如：

$statement = $this->pdo->prepare($query);

您可能更喜欢扩展PDO类，而不是拥有一个保留PDO对象属性的新类。不同之处在于扩展它时，db类的行为与PDO类的行为相同，不同之处在于它将提供其他方法。对于您当前的代码，db类只有您明确定义的方法。

Answer 2

试试这个

class db {

private $options;
private $oPDO;

function __construct() {
    $this->options = array(
        'database_host' => DATABASE_HOST,
        'database_name' => DATABASE_NAME,
        'database_user' => DATABASE_USER,
        'database_pass' => DATABASE_PASS
    );

    $this->connect();
}

private function connect() {
    try {
        $this->oPDO = new PDO('mysql:host=' . $this->options['database_host'] . ';dbname=' . $this->options['database_name'], $this->options['database_user'], $this->options['database_pass']);
        $this->oPDO->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $this->oPDO->exec("set names utf8");

    } catch (PDOException $e) {
        echo 'ERROR: ' . $e->getMessage();
    }
}

public function select($table, $what, $where, $custom) {

    $query = "SELECT " . $what . " FROM " . $table;
    $child = "1";
    $param = array();
    if ($where)
    foreach ($where as $data => $value) {
        if ($child == "1") {
            $query .= " WHERE " . $data . " = '" . $value . "'";
            $param[":" . $data] = $value;
            $child = "next";
        } else {
            $query .= " AND " . $data . " = '" . $value . "'";
            $param[":" . $data] = $value;
        }
    }

    if ($custom)
    $query .= ' ' . $custom;

    $statement = $this->oPDO->prepare($query);
    if ($statement->execute($param))
    return $statement->fetchAll(PDO::FETCH_ASSOC);
    return false;
}

}

OOP PHP - 通过函数传递方法

2 个答案: