How to retrieve parent node using XQuery?

Question

I am using XML and XQuerie. I usually use an XPath expression relative to a parent node to retrieve its child node. But, I am not sure how to do the opposite meaning if I have a child node, how do I retrieve its parent node.

<node id="50>
  <childnode1 childid="51" />
  <childnode2 childid="52" />
</node>

If I have the node <childnode1 childid="51" />, how do I retrieve its parent: <node id="50>

Good question (+1). See my answer for a few possible solutions. — Dimitre Novatchev, Sep 14 '10 at 21:37

score 24 · Accepted Answer · answered Sep 14 '10 at 21:36

Short answer:

..

This selects the parent of the current (context) node.

Longer and more general answers:

//node()[childnode1/@childid="51"]

This selects any node in the document that has a child element named childnode1, that has an attibute childid, whose value is '51'.

One should try to avoid an expression that contains the // abbreviation, because this may be very inefficient. Use '//' only when the structure of the XML document isn't known in advance.

Best answer:

ExpressionSelectingTheChildNode/..

score 5 · Answer 2 · edited Sep 01 '14 at 13:53

5

you use .. to get the parent, like this:

../childnode1

so if you have some XML document like this:

<a id="1">
  <b id="2">
    <c id="3">
      <d id="4"/>
    </c>
    <c id="5"/>
    <c id="6">
      <d id="7"/>
    </c>
  </b>
</a>

then the XQuery

//../d[@id = "4"]

would return the c node with id of 3.

edited Sep 01 '14 at 13:53

Stefan van den Akker

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answered Sep 14 '10 at 20:12

Nathan Hughes

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Your expression means: *from all parents of decendant nodes (the same as all nodes having a child) a `d` child with `id` attribute equal to '4'*. So, it's not what the OP is asking... – Sep 14 '10 at 21:04

score 2 · Answer 3 · answered Mar 15 '13 at 18:20

Here is a more complex example of getting the parent node (..).

Q) Find all situations where one country's most popular language is another country's least popular, and both countries list more than one language. https://prod-c2g.s3.amazonaws.com/db/Winter2013/files/countries.xml

A)

for $b in doc("countries.xml")/countries/country/language
for $c in doc("countries.xml")/countries/country/language
where $b/../@name != $c/../@name 
and data($b) = data($c)
and count($b/../language) > 1
and count($c/../language) > 1
and $b/@percentage = max($b/../language/@percentage)
and $c/@percentage = min($c/../language/@percentage)
return 
  <LangPair language="{data($b)}">
     <MostPopular>{data($b/../@name)}</MostPopular>
     <LeastPopular>{data($c/../@name)}</LeastPopular>
    </LangPair>

score 0 · Answer 4 · answered Apr 25 '17 at 15:10

0

Alternatively, you can also make use of fn:root() Xquery function.

answered Apr 25 '17 at 15:10

bosari

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How to retrieve parent node using XQuery?

4 Answers4

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