PHP 致命错误：在非对象上调用成员函数 hasAttribute()

Question

我在尝试获得siteadvisor.com 评级时在第 18 行遇到错误。错误消息显示"PHP Fatal error: Call to a member function hasAttribute() on a non-object"。我已经包含了我用来获得siteadvisor.com 评级的 ull php 代码。

public function getSiteAdvisor($domain)
{
    try
    {
        $callback_url = "http://www.siteadvisor.com/sites/" . $domain;

        $curl_response = $this->curl->get($callback_url);

        if ($curl_response->headers['Status-Code'] == "200") {

            libxml_use_internal_errors(TRUE);
            $this->dom_doc->loadHTML($curl_response);
            libxml_use_internal_errors(FALSE);

            $xpath = new DOMXPath($this->dom_doc);
            $tmp = $xpath->query('/html/body//div[@id="siteVerdict"]//img')->item(0);

            if ($tmp->hasAttribute('src')) {

                $tmp = $tmp->getAttribute('src');

                if (stripos($tmp, "green") !== false) {
                    $siteadvisor_rating = 1;
                } elseif (stripos($tmp, "yellow") !== false) {
                    $siteadvisor_rating = 2;
                } elseif (stripos($tmp, "red") !== false) {
                    $siteadvisor_rating = 3;
                } else {
                    $siteadvisor_rating = 0;
                }

            } else {
                $siteadvisor_rating = 0;
            }

        } else {
            $siteadvisor_rating = 0;
        }

        $response = array(
            'status' => 'success',
            'data' => array(
                'siteadvisor' => (int)$siteadvisor_rating
            )
        );
    }
    catch (Exception $e)
    {
        $response = array(
            'status' => 'error',
            'msg' => $e->getMessage()
        );
    }
    return $response;       
}

Answer 1

我认为您的 xpath 查询有问题（正如 Gordon 所说）：，改为定位 alt="" 属性。

$domain = 'google.com';
$callback_url = "http://www.siteadvisor.com/sites/" . $domain;
// i know you know what do to just you can just adjust this
$curl_response = file_get_contents($callback_url);
$dom = new DOMDocument();
libxml_use_internal_errors(true);
$dom->loadHTML($curl_response);
libxml_use_internal_errors(true);
$xpath = new DOMXpath($dom);

$siteadvisor_rating = null;
$img_rating = $xpath->query('//div[@id="siteVerdict"]/div/img');

    if($img_rating->length > 0) {
    // haystack
    if($img_rating->item(0)->hasAttribute('alt')) {
        $img_rating = $img_rating->item(0)->getAttribute('alt');
    } elseif ($img->item(0)->hasAttribute('src')) {
        $img_rating = $img_rating->item(0)->getAttribute('src');
    }

    if(stripos($img_rating, 'green') !== false) {
        $siteadvisor_rating = 1;
    } elseif(stripos($img_rating, '') !== false) {
        $siteadvisor_rating = 2;
    } elseif(stripos($img_rating, 'red') !== false) {
        $siteadvisor_rating = 3;
    } else {
        $siteadvisor_rating = 0;
    }

    echo $siteadvisor_rating; // should be 1 for google :)
}

else {
    // no node is found
}