获取< a>的文本当XPath埋入其他标签时<强> [英] Getting the the text of an <a> with XPath when it's buried in another tag e.g. <strong>

问题描述

以下XPath通常足以匹配所有文本包含特定字符串的锚：

  // a [contains（ （），'SENIOR ASSOCIATES'）] 
  

给出这样的例子：

< strong>< strong&
SENIOR ASSOCIATES< br>
< / strong>< / a>

文字包装在< strong> ，在锚点关闭之前还有一个< br> ，所以上面的XPath不会返回任何结果。

XPath如何进行调整，以便它允许包含< strong> < a> $ c>，< i> ，< b> ，< br> 等等，而仍然在标准情况下工作？

解决方案

不要使用 text（）。

  // a [contains（。，'SENIOR ASSOCIATES'） ] 
  

---

与您可能认为的相反， text（）不会给你一个元素的文本。

这是一个节点测试，即一个表达式，一个元素的实际节点（！）列表，即文本节点子元素。

这里：

 < a href =http：// www.freshminds.net/job/senior-associate/\"><strong> 
 SENIOR ASSOCIATES< br> 
< / strong>< / a> 
  

没有 a 的文本节点子元素， 。所有文本节点都是 strong 的子项。所以 text（）给你零结点。

这里：

 < a href =http://www.freshminds.net/job/senior-associate/> <强> 
 SENIOR ASSOCIATES< br> 
< / strong>< / a> 
  

有一个 a 。它是空的（如仅限空白）。

---

。另一方面仅选择一个节点（上下文节点，< a> 本身）。

现在， contains（）需要字符串作为参数。如果一个参数不是字符串，则首先完成对字符串的转换。

将节点集（由1个或多个节点组成）转换为字符串是通过将所有集合^（*）中第一个节点的文本节点后代。因此，使用。（或者其更明确的等价的 string（。））给你 SENIOR ASSOCIATES 被一堆空白包围，因为XML中有一堆空白。

为了消除这个空格，使用 normalize-space（）函数：

  // a [contains（normalize-space（。），'SENIOR ASSOCIATES'）] 
  

或更短，因为当前节点是此函数的默认值：

  // a [contains（normalize-space（），'SENIOR ASSOCIATES'）] 
  

---

^（*）这就是为什么使用 // a [contains（.// text（），' SENIOR ASSOCIATES'）] 可以在上面两个样本中的第一个样本中工作，但不在第二个样本中。

The following XPath is usually sufficient for matching all anchors whose text contains a certain string:

//a[contains(text(), 'SENIOR ASSOCIATES')]

Given a case like this though:

<a href="http://www.freshminds.net/job/senior-associate/"><strong>
                        SENIOR ASSOCIATES <br> 
                        </strong></a>

The text is wrapped in a <strong>, also there's also a <br> before the anchor closes, and so the above XPath returns nothing.

How can the XPath be adapted so that it allows for the <a> containing additional tags such as <strong>, <i>, <b>, <br> etc. while still working in the standard case?

解决方案

Don't use text().

//a[contains(., 'SENIOR ASSOCIATES')]

---

Contrary to what you might think, text() does not give you the text of an element.

It is a node test, i.e. an expression that selects a list of actual nodes (!), namely the text node children of an element.

Here:

<a href="http://www.freshminds.net/job/senior-associate/"><strong>
                    SENIOR ASSOCIATES <br> 
                    </strong></a>

there are no text node children of a. All the text nodes are children of strong. So text() gives you zero nodes.

Here:

<a href="http://www.freshminds.net/job/senior-associate/"> <strong>
                    SENIOR ASSOCIATES <br> 
                    </strong></a>

there is one text node child of a. It's empty (as in "whitespace only").

---

. on the other hand selects only one node (the context node, the <a> itself).

Now, contains() expects strings as its arguments. If one argument is not a string, a conversion to string is done first.

Converting a node set (consisting of 1 or more nodes) to string is done by concatenating all text node descendants of the first node in the set^(*). Therefore using . (or its more explicit equivalent string(.)) gives you SENIOR ASSOCIATES surrounded by a bunch of whitespace, because there is a bunch of whitespace in your XML.

To get rid of that whitespace, use the normalize-space() function:

//a[contains(normalize-space(.), 'SENIOR ASSOCIATES')]

or, shorter, because "the current node" is the default for this function:

//a[contains(normalize-space(), 'SENIOR ASSOCIATES')]

---

^(*) That's the reason why using //a[contains(.//text(), 'SENIOR ASSOCIATES')] would work in the first of the two samples above but not in the second one.

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