XPath : select all following siblings until another sibling

Question

Here is an excerpt of my xml :

<node/>
<node/>
<node id="1">content</node>
<node/>
<node/>
<node/>
<node id="2">content</node>
<node/>
<node/>

I am positioned in the node[@id='1']. I need an Xpath to match all the <node/> elements until the next not empty node (here node[@id='2']).

Edit: the @id attributes are only to explain my problem more clearly, but are not in my original XML. I need a solution which does not use the @id attributes.

I do not want to match the empty siblings after node[@id='2'], so I can't use a naive following-sibling::node[text()=''].

How can I achieve this ?

See also: http://stackoverflow.com/questions/2165566/xslt-select-following-sibling-until-reaching-a-specified-tag — WBT, Jul 09 '12 at 21:56
This might be of use: [http://stackoverflow.com/questions/2063619/how-to-reformat-xml-with-group-adjacent-xslt](http://stackoverflow.com/questions/2063619/how-to-reformat-xml-with-group-adjacent-xslt) — Igor Nadj, Jan 29 '10 at 13:25

Tomalak · Accepted Answer · 2010-01-29T12:43:19.507

23

You could do it this way:

../node[not(text()) and preceding-sibling::node[@id][1][@id='1']]

where '1' is the id of the current node (generate the expression dynamically).

The expression says:

from the current context go to the parent
select those child nodes that
have no text and
from all "preceding sibling nodes that have an id" the first one must have an id of 1

If you are in XSLT you can select from the following-sibling axis because you can use the current() function:

<!-- the for-each is merely to switch the current node -->
<xsl:for-each select="node[@id='1']">
  <xsl:copy-of select="
    following-sibling::node[
      not(text()) and
      generate-id(preceding-sibling::node[@id][1])
      =
      generate-id(current())
    ]
  " />
</xsl:for-each>

or simpler (and more efficient) with a key:

<xsl:key 
  name="kNode" 
  match="node[not(text())]" 
  use="generate-id(preceding-sibling::node[@id][1])"
/>

<xsl:copy-of select="key('kNode', generate-id(node[@id='1']))" />

edited Jan 29 '10 at 12:43

answered Jan 29 '10 at 12:34

Tomalak

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I finally went another route, because I'm outside of XSLT, so I select all the following-sibling nodes, and iterate on them, and stop my loop when I encounter the next not empty. I accept your answer as the most thorough, because I now believe there is no one-liner in XPath to do what I asked. – glmxndr Feb 03 '10 at 08:09
@subtenante: Erm - but there *is* an XPath one-liner that does that right in my answer?! – Tomalak Feb 03 '10 at 08:16
yes, you are right, my question in not really clear about the fact that the id attributes I have put were only for show and explaining the problem. I actually have not the id attributes in my XML. – glmxndr Feb 03 '10 at 08:27
11

@subtenante: That's why you should never make up your code samples when you want a real problem solved. – Tomalak Feb 03 '10 at 09:54

Phrogz · Answer 2 · 2011-10-20T17:24:29.857

Simpler than the accepted answer:

//node[@id='1']/following-sibling::node[following::node[@id='2']]

Find a node anywhere whose id is '1'
Now find all the following sibling node elements
...but only if those elements also have a node with id="2" somewhere after them.

Shown in action with a more clear test document (and legal id values):

xml = '<root>
<node id="a"/><node id="b"/>
<node id="c">content</node>
<node id="d"/><node id="e"/><node id="f"/>
<node id="g">content</node>
<node id="h"/><node id="i"/>
</root>'

# A Ruby library that uses libxml2; http://nokogiri.org
require 'nokogiri'; doc = Nokogiri::XML(xml)

expression = "//node[@id='c']/following-sibling::node[following::node[@id='g']]"
puts doc.xpath(expression)
#=> <node id="d"/>
#=> <node id="e"/>
#=> <node id="f"/>

Why do you chose the `following` axis here? That may give false positives further down the road, if the document is larger (besides from the following-axis being more slower than any other axis). — Abel, Oct 17 '15 at 22:53

score 8 · Answer 3 · answered Jan 29 '10 at 13:12

XPath 2.0 has the operators '<<' and '>>' where node1 << node2 is true if node1 precedes node2 in document order. So based on that with XPath 2.0 in an XSLT 2.0 stylesheet where the current node is the node[@id = '1'] you could use

  following-sibling::node[not(text()) and . << current()/following-sibling::node[@od][1]]

That also needs the current() function from XSLT, so that is why I said "with XPath 2.0 in an XSLT 2.0 stylesheet". The syntax above is pure XPath, in an XSLT stylesheet you would need to escape '<<' as '<<'.

XPath : select all following siblings until another sibling

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