xml XPath 选择多个标签
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XPath to select multiple tags
提问by nickf
Given this simplified data format:
鉴于这种简化的数据格式：
<a>
<b>
<c>C1</c>
<d>D1</d>
<e>E1</e>
<f>don't select this one</f>
</b>
<b>
<c>C2</c>
<d>D2</d>
<e>E1</e>
<g>don't select me</g>
</b>
<c>not this one</c>
<d>nor this one</d>
<e>definitely not this one</e>
</a>
How would you select all the Cs, Ds and Es that are children of Belements?
您将如何选择作为元素子元素的所有Cs、Ds 和Es B？
Basically, something like:
基本上，类似于：
a/b/(c|d|e)
In my own situation, instead of just a/b/, the query leading up to selecting those C, D, Enodes is actually quite complex so I'd like to avoid doing this:
在我自己的情况下，而不仅仅是a/b/，导致选择那些C, D,E节点的查询实际上非常复杂，所以我想避免这样做：
a/b/c|a/b/d|a/b/e
Is this possible?
这可能吗？
回答by Dimitre Novatchev
One correct answer is:
一个正确的答案是：
/a/b/*[self::c or self::d or self::e]
Do note that this
请注意，这
a/b/*[local-name()='c' or local-name()='d' or local-name()='e']
is both too-long and incorrect. This XPath expression will select nodes like:
既太长又不正确。此 XPath 表达式将选择如下节点：
OhMy:c
NotWanted:d
QuiteDifferent:e
回答by annakata
You can avoid the repetition with an attribute test instead:
您可以使用属性测试来避免重复：
a/b/*[local-name()='c' or local-name()='d' or local-name()='e']
Contrary to Dimitre's antagonistic opinion, the above is not incorrectin a vacuum where the OP has not specified the interaction with namespaces. The self::axis is namespace restrictive, local-name()is not. If the OP's intention is to capture c|d|eregardless of namespace (which I'd suggest is even a likely scenario given the OR nature of the problem) then it is "another answer that still has some positive votes" which is incorrect.
与 Dimitre 的反对意见相反，在 OP 没有指定与命名空间的交互的真空中，上述内容并没有错。该self::轴是命名空间限制性的，local-name()是没有的。如果 OP 的意图是不c|d|e考虑名称空间而进行捕获（鉴于问题的 OR 性质，我认为这甚至是一种可能的情况）那么它是“另一个仍然有一些赞成票的答案”，这是不正确的。
You can't be definitive without definition, though I'm quite happy to delete my answer as genuinely incorrect if the OP clarifies his question such that I am incorrect.
如果没有定义，你就不能确定，尽管如果 OP 澄清了他的问题，我很高兴将我的答案删除为真正不正确的答案。
回答by Pavel Repin
Why not a/b/(c|d|e)? I just tried with Saxon XML library(wrapped up nicely with some Clojure goodness), and it seems to work.
abc.xmlis the doc described by OP.
为什么不a/b/(c|d|e)呢？我刚刚尝试了Saxon XML 库（用一些 Clojure 的优点很好地结束了），它似乎有效。
abc.xml是 OP 描述的文档。
(require '[saxon :as xml])
(def abc-doc (xml/compile-xml (slurp "abc.xml")))
(xml/query "a/b/(c|d|e)" abc-doc)
=> (#<XdmNode <c>C1</c>>
#<XdmNode <d>D1</d>>
#<XdmNode <e>E1</e>>
#<XdmNode <c>C2</c>>
#<XdmNode <d>D2</d>>
#<XdmNode <e>E1</e>>)
回答by Calvin
Not sure if this helps, but with XSL, I'd do something like:
不确定这是否有帮助，但是使用 XSL，我会执行以下操作：
<xsl:for-each select="a/b">
<xsl:value-of select="c"/>
<xsl:value-of select="d"/>
<xsl:value-of select="e"/>
</xsl:for-each>
and won't this XPath select all children of B nodes:
并且此 XPath 不会选择 B 节点的所有子节点：
a/b/*
