PHP DOM解析器错误

Question

我有解析网页的代码。包含每个页面解析的foreach。第一个循环正确执行，另一个在解析器中失败。致命错误：调用一个成员函数find（）会在C语言的非对象：\ WAMP \ WWW \上线解析器\ dom.php 1129

解析器是PHP简单的HTML DOM解析器 - http://sourceforge.net/projects/simplehtmldom/

<?php 
header('Content-Type: text/html; charset=utf-8'); 
include ('dom.php'); 
$mysql = mysqli_connect("localhost", "root", "", "db"); 


$import['id'][]=3; 
$import['url'][]='http://sitea.com'; 
$import['id'][]=2; 
$import['url'][]='http://siteb.com'; 
$import['id'][]=1; 
$import['url'][]='http://sitec.com'; 

for($i=0; $i<count($import['id']); $i++){ 
    $coupons=array(); 
    $id=0; 
    $parser = new simple_html_dom(); 
    $parser->load_file($import['url'][$i]); 

    foreach($parser->find('section[class=couponList]', 0)->find('article[class=coupon]') as $coupon){ 
     $coupons[$id]['name']=trim($coupon->find('div[class=name]',0)->plaintext); 
     $date=explode(' ', trim($coupon->find('p[class=dateFormat]',0)->plaintext)); 
     $coupons[$id]['date-from']=strtotime(trim($date[45])); 
     $coupons[$id]['date-to']=strtotime(trim($date[130])); 
     $coupons[$id]['description']=trim($coupon->find('div[class=description]',0)->plaintext); 
     $coupons[$id]['sale']=@trim($coupon->find('div[class=couponImageContainer] div p',0)->plaintext); 
     $coupons[$id]['id']=$coupon->attr['data-id']; 

     //Code 
     if(trim($coupon->find('div[class=couponColorType]',0)->plaintext)=='Kód'){ 
      $parser2 = new simple_html_dom(); 
      $parser2->load_file($import['url'][$i].'?cpn_id='.$coupon->attr['data-id']); 
      $coupons[$id]['code']=strip_tags($parser2->find('span[class=popupCode]',0)); 
      $coupons[$id]['type']="kod"; 
     }else{ 
      $coupons[$id]['type']="nabidka"; 
      $page=file_get_contents('http://slevovekody.com/r/'.$coupon->attr['data-id']); 
      $data=explode("window.location = '", $page); 
      $data=explode("';", @$data[1]); 

      $u=explode('http://', $data[0]); 
      if(count($u)>2){ 
       $u='http://'.$u['2']; 
      }else{ 
       $u=$data[0]; 
      } 
      $u=explode('?', $u); 
      $coupons[$id]['url']=$u[0]; 
     } 
     $id++; 
    } 
    foreach($coupons as $c){    
     if(mysqli_num_rows(mysqli_query($mysql, "SELECT * FROM coupon WHERE id_import='".$c['id']."'"))==0){ 
      mysqli_query($mysql, "INSERT INTO `coupon` (`eshop`, `id_import`, `name`, `alias`, `description`, `type`, `from`, `to`, `code`, `url`, `sale`) VALUES ('".$import['id'][$i]."', '".$c['id']."', '".$c['name']."', '".makeAlias($c['name'])."', '".$c['description']."', '".strtolower($c['type'])."', '".$c['date-from']."', '".$c['date-to']."', '".@$c['code']."', '".@$c['url']."', '".$c['sale']."')"); 
     } 
    } 
    var_dump($coupons); 
    unset($coupons); 
} 

？

>

错误

Fatal error: Call to a member function find() on a non-object in C:\wamp\www\parser\dom.php on line 1129 
Call Stack 
# Time Memory Function Location 
1 0.0010 291880 {main}() ..\index.php:0 
2 5.5803 21923208 simple_html_dom->find() ..\index.php:20 

错误是上一行：

foreach($parser->find('section[class=couponList]', 0)->find('article[class=coupon]') as $coupon){ 

Answer 1

如果find()调用找不到任何内容（例如，没有匹配），那么它返回NULL。因此，您可以不是链find（）调用您的方式，因为任何失败的查找将返回null并导致您的“非对象调用”。

e.g

$x = $dom->find('element_that_does_not_exist'); // $x becomes null 
$x->find('body'); 

会做null->find()的等价物。

您必须捕获中间结果并查看是否有任何匹配，例如，

$x = $dom->find('element_that_does_not_exist'); 
if (!is_null($x)) { 
    $y = $x->find('other stuff'); 
}