访问现有属性返回null [英] accessing existing attribute returns null

问题描述

我写了下面的表达式以从下面的xml文件中检索信息，但是返回的结果是空的，并且索引出来。

i wrote the below expression to retrieve info from the below xml file, but the returned results is null and index out of bound.

请让我知道如何从该元素检索数据：

please let me know how to retrieve data from this element:

 <ele k="maxspeed:zone" v="60"/>

表达：

"//node[@lat='53.0337395'] [@lon='8.8489255']/following-sibling/following-   
sibling::ele[1]/@v"

xml ：

<?xml version='1.0' encoding='utf-8' ?>
<osm>
<node id="25779111" lat="53.0334062" lon="8.8461545"/>
<node id="25779112" lat="53.0338904" lon="8.846314"/>
<node id="25779119" lat="53.0337395" lon="8.8489255"/>
<tag k="maxspeed" v="30"/>
<tag k="maxspeed:zone" v="yes"/>
<ele k="maxspeed:zone" v="60"/>
<node id="25779114" lat="53.334062" lon="8.841545"/>
<node id="25779117" lat="53.338904" lon="8.84614"/>
<node id="25779110" lat="53.33795" lon="8.489255"/>
<tag k="maxspeed" v="32"/>
<tag k="maxspeed:zone" v="no"/>
</osm>

推荐答案

你几乎在那里 - 你需要添加 :: tag [1] 到第一个 follow-sibling ，像这样：

You are almost there - you need to add ::tag[1] to the first following-sibling, like this:

"//node[@lat='53.0337395'] [@lon='8.8489255']/following-sibling::tag[1]/following-sibling::ele[1]/@v"

这将检索 Attribute ='v = 60'

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