symfony - 如何安全地检查节点是否为空？（Symfony 2 爬虫）

Question

当我尝试从页面中获取一些不存在的内容时，我发现了这个错误：

The current node list is empty.
500 Internal Server Error - InvalidArgumentException 

如何安全地检查此内容是否存在？这里有一些不起作用的例子：

if($crawler->filter('.PropertyBody')->eq(2)->text()){
    // bla bla
}

if(!empty($crawler->filter('.PropertyBody')->eq(2)->text())){
    // bla bla
}
if(($crawler->filter('.PropertyBody')->eq(2)->text()) != null){
    // bla bla
}

谢谢，我帮助自己：

$count = $crawler->filter('.PropertyBody')->count();
if($count > 2){
    $marks = $crawler->filter('.PropertyBody')->eq(2)->text();
}

Answer 1

$marks = $crawler->filter('.PropertyBody')->count()
    ? $crawler->filter('.PropertyBody')->eq(2)->text() 
    : '';

Answer 2

你有没有尝试过这样的事情？

$text = null;
if (!empty($body = $crawler->filter('.PropertyBody'))) {
    if (!empty($node = $body->eq(2))) {
        $text = $node->text();
    }
}

$this->assertContains('yourText', $text);

Answer 3

try {
    $text = $crawler->filter('.PropertyBody')->eq(2)->text();
} catch (\InvalidArgumentException $e) {
    // Handle the current node list is empty..
}