xml XPATH 选择根元素
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XPATH selecting the root element
提问by heymega
Is there a simple way of moving back to the root node within any given context. The XML document I'm working with is extremely large and would require using ../.. about a dozen times!!
是否有一种简单的方法可以在任何给定的上下文中移回根节点。我正在使用的 XML 文档非常大，需要使用 ../.. 大约十几次！！
Any help is greatly appreciated guys.
任何帮助都非常感谢伙计们。
采纳答案by keeney
I'm guessing you are in a predicate here? and want to return to look at data higher up the tree for your condition?
我猜你在这里是谓词？并想返回查看树更高层的数据以了解您的情况？
You should be able to start with a leading / and then work your way back down e.g
您应该能够从领先的 / 开始，然后再往下走，例如
/vehicles/cars/car[@id = /vehicles/featuredVehicle/@id]
回答by Frank Bollack
回答by Dibbeke
You can use the ancestor axis. Say you have this document:
您可以使用祖先轴。假设你有这个文件：
<a><b><c></c></b></a>
Then a/b/c/ancestor::a brings the context to the c node and then back to the a node.
然后 a/b/c/ancestor::a 将上下文带到 c 节点，然后返回到 a 节点。
回答by deadlyvices
Yes. Use "/" as your XPath expression. This will select the root element for you. "//" selects the root and all its descendants.
是的。使用“/”作为 XPath 表达式。这将为您选择根元素。"//" 选择根及其所有后代。
