Symfony DomCrawler：查找具有特定属性值的元素 [英] Symfony DomCrawler: Find element with specific attribute value
问题描述
我正在使用DomCrawler组件： http://symfony.com/doc/current/components/dom_crawler .html
I'm using the DomCrawler component: http://symfony.com/doc/current/components/dom_crawler.html
我想使用类似CSS的语法来获取具有特定属性值的元素。
I'd like to, using the CSS like syntax, get an element with a specific attribute value.
以下是我使用的代码：
$link = $crawler->filter('#product a[data-type="bla"]');
这似乎工作，因为以下返回1：
This seems to work, as the following returns 1:
echo count($link);
但是，我绝对不能进一步过滤这个。我不能做：
However, I can never not filter further than this. I can not do:
$link->filter('img')->attr('src');
这会导致以下错误消息：
This results in the following error message:
The current node list is empty.
但是，我知道这不是。
However, I know for certain that it isn't.
我已经尝试过其他元素的语法，它总是一样的。我正在做错事，或者这是不可能的（用css语法，而不是xpath）
I've tried the syntax on other elements and it's always the same. I am doing something wrong or is this not possible (with css like syntax, not xpath)
推荐答案
我无法按照你的问题。使用 两个 软件库的现有开发版本（以及2.1.0和2.2.0版本），dom-crawler 和 css-selector ，您提供的示例代码可以很好地考虑以下示例HTML： p>
I can not follow your problem. Using the current development versions (and also 2.1.0 and 2.2.0 versions) of the two software libraries dom-crawler and css-selector, the example code you provided works just fine considering the following example HTML:
<?php
use Symfony\Component\DomCrawler\Crawler;
// require dependencies here
$html = <<<'HTML'
<!DOCTYPE html>
<html>
<body>
<p class="message">Hello World!</p>
<p>Hello Crawler!</p>
<div id="product">
<a data-type="bla">
<img src="OK">
</a>
</div>
</body>
</html>
HTML;
$crawler = new Crawler($html);
$link = $crawler->filter('#product a[data-type="bla"]');
echo var_dump(count($link));
var_dump($link->filter('img')->attr('src'));
正如你所看到的，这正是你的代码（只是有点不同，但本质上不是）以下输出逐字：
As you can see this is exactly your code (only a little different but essentially not), which gives the following output verbatim:
int(1)
string(2) "OK"
第一个输出行是 count（） ，第二个是src属性值。
The first output line is the count() and the second is the src attribute value.
您是否运行作曲家更新？您是否仔细检查了输入？
Have you run composer update? Have you double-checked the input?
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