Warning: Invalid argument supplied for foreach() in /.../ipn_res.php on line 28

Warning: Invalid argument supplied for foreach() in /.../ipn_cls.php on line 30

第28行是foreach循环：

foreach ($paypal_ipn->paypal_post_vars as $key=>$value) {
    if (getType($key)=="string") {
        eval("\\$$key=\\$value;");
    }
}

第30行也是foreach循环：

foreach($this->paypal_post_vars AS $key => $value) {
    if (@get_magic_quotes_gpc()) {
        $value = stripslashes($value);
    }
    $values[] = "$key" . "=" . urlencode($value);
}

我认为这些错误的根本原因是：

//This is located before foreach loop in ipn_res.php
require_once("ipn_cls.php");

$paypal_info = $HTTP_POST_VARS;
$paypal_ipn = new paypal_ipn($paypal_info);

类paypal\\u ipn的构造函数传递了一个非数组变量，因为尚未发送任何可填充的内容$HTTP_POST_VARS. Wordpress运行的代码不在其中时就不是这样了。我该如何摆脱这一切？

if( !isset( $paypal_ipn->paypal_post_vars ) )
    $paypal_ipn->paypal_post_vars = array();