xml XPath：如何检查属性是否存在？
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XPath: How to check if an attribute exists?
提问by Byron Whitlock
Given the following XML, how do I write an XPath query to pull nodes where the attribute fooexists?:
给定以下 XML，我如何编写 XPath 查询来拉取属性foo存在的节点？：
<node1>
<node2>
<node3 foo='bar'></node3>
<node3></node3>
<node3 bar='foo'></node3>
<node3 foo='foobar'></node3>
</node2>
</node1>
回答by Felix Kling
Short and sweet:
简短而甜蜜：
//*[@foo]
Of course you should use a more specific expression. But with [@attributeName]you get all nodes which have that attribute.
当然，您应该使用更具体的表达方式。但是随着[@attributeName]您获得具有该属性的所有节点。
回答by Ru5
Use the following XPath expression
使用以下 XPath 表达式
//*[boolean(@foo)]
回答by fritz
If you use and xpath, this maybe can help you:
如果您使用和 xpath，这可能可以帮助您：
count(//*[@foo])
it will return count of node/child that have attribute foo
它将返回具有属性 foo 的节点/子节点的计数
