按类名获取DOM元素 [英] Getting DOM elements by classname

问题描述

我使用 PHP DOM ，我想尝试获取DOM节点中具有给定类名称的元素。

更新：我最后使用机械化

解决方案

更新：Xpath版本 * [@ class〜='my-class'] css selector

hakre的评论我很好奇，并研究了 Zend_Dom_Query 后面的代码。它看起来像上面的选择器被编译为以下xpath（未测试）：

[contains（concat（''，normalize-space class），''），'my-class'）]

，所以php是：

  $ dom = new DomDocument（）; 
 $ dom-> load（$ filePath）; 
 $ finder = new DomXPath（$ dom）; 
 $ classname =my-class; 
 $ nodes = $ finder-> query（// * [contains（concat（''，normalize-space（@class），''），'$ classname'）]）; 
  

基本上我们在这里做的是规范化 class 属性，使得即使单个类也由空格限定，完整的类列表也在空格中。然后追加类，我们正在搜索一个空格。这样，我们正在有效地查找并找到 my-class 的实例。

---

使用xpath选择器？

  $ dom = new DomDocument 
 $ dom-> load（$ filePath）; 
 $ finder = new DomXPath（$ dom）; 
 $ classname =my-class; 
 $ nodes = $ finder-> query（// * [contains（@class，'$ classname'）]）; 
  

如果只有一种类型的元素，你可以替换 * 与特定的标记名。

如果你需要做很多这样非常复杂的选择器，我会建议 Zend_Dom_Query ： p>

  $ finder = new Zend_Dom_Query（$ html）; 
 $ classname ='my-class'; 
 $ nodes = $ finder-> query（* [class〜= \$ classname\]）; 
  

I'm using PHP DOM and I'm trying to get an element within a DOM node that have a given class name. What's the best way to get that sub-element?

Update: I ended up using Mechanize for PHP which was much easier to work with.

解决方案

Update: Xpath version of *[@class~='my-class'] css selector

So after my comment below in response to hakre's comment i got curious and looked into the code behind Zend_Dom_Query. It looks like the above selector is compiled to the following xpath (untested):

[contains(concat(' ', normalize-space(@class), ' '), ' my-class ')]

so the php would be:

$dom = new DomDocument();
$dom->load($filePath);
$finder = new DomXPath($dom);
$classname="my-class";
$nodes = $finder->query("//*[contains(concat(' ', normalize-space(@class), ' '), ' $classname ')]");

Basically all we do here is normalize the class attribute so that even a single class is bounded by spaces, and the complete class list is bounded in spaces. Then append class we are searching for with a space. This way we are effectively looking for and find only instances of my-class.

---

Use an xpath selector?

$dom = new DomDocument();
$dom->load($filePath);
$finder = new DomXPath($dom);
$classname="my-class";
$nodes = $finder->query("//*[contains(@class, '$classname')]");

If it is only ever one type of element you can replace the * with the particular tagname.

If you need to do alot of this with very complex selector i would recommend Zend_Dom_Query which supports CSS selector syntax (a la jQuery):

$finder = new Zend_Dom_Query($html);
$classname = 'my-class';
$nodes = $finder->query("*[class~=\"$classname\"]");

这篇关于按类名获取DOM元素的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！