xml XPath 可以只返回具有 X 子节点的节点吗？
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Can XPath return only nodes that have a child of X?
提问by Ryan Stille
Is it possible to use XPath to select only the nodes that have a particular child elements? For example, from this XML I only want the elements in pets that have a child of 'bar'. So the resulting dataset would contain the lizardand pigelements from this example:
是否可以使用 XPath 仅选择具有特定子元素的节点？例如，从这个 XML 中，我只想要宠物中具有“bar”子元素的元素。因此，生成的数据集将包含此示例中的lizard和pig元素：
<pets>
<cat>
<foo>don't care about this</foo>
</cat>
<dog>
<foo>not this one either</foo>
</dog>
<lizard>
<bar>lizard should be returned, because it has a child of bar</bar>
</lizard>
<pig>
<bar>return pig, too</bar>
</pig>
</pets>
This Xpath gives me all pets: "/pets/*", but I only want the pets that have a child node of name 'bar'.
这个 Xpath 给了我所有的 pets: "/pets/*"，但我只想要具有 name 子节点的宠物'bar'。
回答by Chris Marasti-Georg
Here it is, in all its glory
在这里，在它所有的荣耀中
/pets/*[bar]
English: Give me all children of petsthat have a child bar
给我所有pets有孩子的孩子bar
回答by Ryan Stille
/pets/child::*[child::bar]
My pardon, I did not see the comments to the previous reply.
对不起，我没有看到上一个回复的评论。
But in this case I'd rather prefer using the descendant::axis, which includes all elements down from specified:
但在这种情况下，我宁愿使用descendant::轴，它包括指定以下的所有元素：
/pets[descendant::bar]
回答by Hirnhamster
Just in case you wanted to be more specific about the children - you can also use selectors on them.
以防万一您想更具体地了解孩子 - 您也可以对他们使用选择器。
Example:
例子：
<pets>
<cat>
<foo>don't care about this</foo>
</cat>
<dog>
<foo>not this one either</foo>
</dog>
<lizard>
<bar att="baz">lizard should be returned, because it has a child of bar</bar>
</lizard>
<pig>
<bar>don't return pig - it has no att=bar </bar>
</pig>
</pets>
Now, you only care about all petshaving any child barthat has an attribute attwith value baz. You can use the following xpath expression:
现在，您只关心所有pets具有valuebar属性的attbaz孩子。您可以使用以下 xpath 表达式：
//pets/*[descendant::bar[@att='baz']]
Result
结果
<lizard>
<bar att="baz">lizard should be returned, because it has a child of bar</bar>
</lizard>
