[英]How to get the attribute value of a parent element in Xpath if Child element exists?
I'm new to XPath and not sure how to get the attribute value of a parent element if a specific child element exists. 我是XPath的新手,并且不确定存在特定子元素时如何获取父元素的属性值。
<planet name="Earth" star="Sun">
<primary>
<oxygen>20.95%</oxygen>
<water>70.8%</water>
</primary>
</planet>
What should be my XPath to get the @name
attribute from the element <planet>
if the <oxygen>
element is present within primary? 如果<oxygen>
元素存在于主对象中,那么从元素<planet>
获取@name
属性的XPath应该是什么?
You can use a predicate to look down the tree. 您可以使用谓词向下看树。 This selects all planet
elements that have primary/oxygen
subelements. 这将选择所有具有primary/oxygen
子元素的planet
元素。 I added a root element assuming this is buried in a document somewhere. 我添加了一个根元素,假设它被埋在文档的某个地方。
import lxml.etree
doc = lxml.etree.fromstring("""<root>
<planet name="Earth" star="Sun">
<primary>
<oxygen>20.95%</oxygen>
<water>70.8%</water>
</primary>
</planet>
</root>""")
print(doc.xpath('planet[primary/oxygen]/@name'))
The correct answer depends on you current XPath axis . 正确的答案取决于您当前的XPath轴 。 So if your current axis is <oxygen>
the XPath expression to access the @name
attribute of the element <planet>
would be: 因此,如果您当前的轴是<oxygen>
,则访问元素<planet>
的@name
属性的XPath表达式将是:
../../@name
Or encapsulated in an XSLT expression: 或封装在XSLT表达式中:
<xsl:value-of select="../../@name" />
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.