使用嵌套的 XPath 谓词......精炼 [英] Working With Nested XPath Predicates ... Refined

问题描述

所有很棒的答案！但问题值得细化......

All great answers! But the question deserves refinement ...

我有以下示例 XML ...

I've got the following sample XML ...

<objects>
    <object objectId="1123" ... />
    <properties refObjectId="1123" ... />
    <properties refObjectId="1123" refPropertyId="2311" ... />
    <properties refObjectId="1123" refPropertyId="4611" ... />
    <object objectId="2123" ... />
    <properties refObjectId="2123" refPropertyId="4311" ... />
    <properties refObjectId="2123" refPropertyId="8611" ... />
    ....
</objects>

... 以及以下 XPath 查询...

... and the following XPath query ...

//object[//properties[@refObjectId=@objectId and not(@refPropertyId)]]

我认为这个查询会返回所有 object 节点，其中有一个 properties 节点，该节点具有一个 refObjectId 属性等于 object 节点的 objectId 属性并且没有 'refPropertyId' 属性......即只有对象 1123，而不是对象 2123......但它没有.嵌套谓词中的 @objectId 似乎没有引用 object 节点的 objectId 属性.

I thought this query would return all object nodes where there is a properties node that has a refObjectId attribute that equals the objectId attribute of the object node and no 'refPropertyId' attribute ... namely object 1123 only, not object 2123 ... but it doesn't. It seems the @objectId in the nested predicate does not refer to the objectId attribute of the object node.

有什么想法吗?我知道 XML 结构不像您期望的那样嵌套，但这种结构是有原因的.

Any ideas? I know the XML structure isn't nested as you would expect, but there are reasons for this structure.

推荐答案

通常，您应该尽可能避免使用 //.我会考虑改写:

Generally you should avoid using // where you can. I'd consider rephrasing:

//object[../properties/@refObjectId=@objectId]

在提供的表达式中，您的嵌套谓词实际上是在检查

In the expression provided, your nested predicate is actually checking for

//properties/@refObjectId=//properties/@objectId 

其中没有.

我希望这会有所帮助！

由于问题已更新，这里是更新的回复:您添加了似乎嵌套谓词中的 @objectId 并未引用对象节点的 objectId 属性."你是绝对正确的！所以让我们修复它！

Since the question has been updated here is an updated response: You added "It seems the @objectId in the nested predicate does not refer to the objectId attribute of the object node." You're absolutely right! So let's fix it!!

//object[../properties[not(@refPropertyId)]/@refObjectId=@objectId]

这应该更接近你所追求的！

This should be closer to what you're after!

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