如果子元素存在，如何在Xpath中获取父元素的属性值?

问题描述

我是 XPath 的新手，如果存在特定的子元素，我不确定如何获取父元素的属性值.

I'm new to XPath and not sure how to get the attribute value of a parent element if a specific child element exists.

<planet name="Earth" star="Sun">
      <primary>
            <oxygen>20.95%</oxygen>
            <water>70.8%</water>
      </primary>
</planet>

如果 元素是从元素 获取 @name 属性，我的 XPath 应该是什么?存在于初级?

What should be my XPath to get the @name attribute from the element <planet> if the <oxygen> element is present within primary?

推荐答案

您可以使用谓词向下查看树.这将选择所有具有 primary/oxygen 子元素的 planet 元素.我添加了一个根元素，假设它被埋在某个文档中.

You can use a predicate to look down the tree. This selects all planet elements that have primary/oxygen subelements. I added a root element assuming this is buried in a document somewhere.

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'))

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