XPath: Get parent node from child node

XmlXpath

Xml Problem Overview


I need get the parent node for child node title 50

At the moment I am using only

//*[title="50"]

How could I get its parent? Result should be the store node.


<?xml version="1.0" encoding="utf-8"?>
<d:data xmlns:d="defiant-namespace" d:mi="23">
    <store d:mi="22">
        <book price="12.99" d:price="Number" d:mi="4">
            <title d:constr="String" d:mi="1">Sword of Honour</title>
            <category d:constr="String" d:mi="2">fiction</category>
            <author d:constr="String" d:mi="3">Evelyn Waugh</author>
        </book>
        <book price="8.99" d:price="Number" d:mi="9">
            <title d:constr="String" d:mi="5">Moby Dick</title>
            <category d:constr="String" d:mi="6">fiction</category>
            <author d:constr="String" d:mi="7">Herman Melville</author>
            <isbn d:constr="String" d:mi="8">0-553-21311-3</isbn>
        </book>
        <book price="8.95" d:price="Number" d:mi="13">
            <title d:constr="String" d:mi="10">50</title>
            <category d:constr="String" d:mi="11">reference</category>
            <author d:constr="String" d:mi="12">Nigel Rees</author>
        </book>
        <book price="22.99" d:price="Number" d:mi="18">
            <title d:constr="String" d:mi="14">The Lord of the Rings</title>
            <category d:constr="String" d:mi="15">fiction</category>
            <author d:constr="String" d:mi="16">J. R. R. Tolkien</author>
            <isbn d:constr="String" d:mi="17">0-395-19395-8</isbn>
        </book>
        <bicycle price="19.95" d:price="Number" d:mi="21">
            <brand d:constr="String" d:mi="19">Cannondale</brand>
            <color d:constr="String" d:mi="20">red</color>
        </bicycle>
    </store>
</d:data>

Xml Solutions


Solution 1 - Xml

Use the parent axes with the parent node's name.

//*[title="50"]/parent::store

This XPath will only select the parent node if it is a store.

But you can also use one of these

//*[title="50"]/parent::*
//*[title="50"]/..

These xpaths will select any parent node. So if the document changes you will always select a node, even if it is not the node you expect.

EDIT

> What happens in the given example where the parent is a bicycle but the parent of the parent is a store? > > Does it ascent?

No, it only selects the store if it is a parent of the node that matches //*[title="50"].

> If not, is there a method to ascent in such cases and return None if there is no such parent?

Yes, you can use ancestor axes

//*[title="50"]/ancestor::store

This will select all ancestors of the node matching //*[title="50"] that are ` stores. E.g.

<data xmlns:d="defiant-namespace" d:mi="23">
	<store mi="1">
		<store mi="22">
			<book price="8.95" d:price="Number" d:mi="13">
				<title d:constr="String" d:mi="10">50</title>
				<category d:constr="String" d:mi="11">reference</category>
				<author d:constr="String" d:mi="12">Nigel Rees</author>
			</book>
		</store>
	</store>
</data>

XPath selection result

Solution 2 - Xml

Just as an alternative, you can use ancestor.

//*[title="50"]/ancestor::store

It's more powerful than parent since it can get even the grandparent or great great grandparent

Solution 3 - Xml

You can use the two dots at the end of expression, too. See this example:

//*[title="50"]/..

Solution 4 - Xml

New, improved answer to an old, frequently asked question...

> How could I get its parent? Result should be the store node.

Use a predicate rather than the parent:: or ancestor:: axis

Most answers here select the title and then traverse up to the targeted parent or ancestor (store) element. A simpler, direct approach is to select parent or ancestor element directly in the first place, obviating the need to traverse to a parent:: or ancestor:: axes:

//*[book/title = "50"]

Should the intervening elements vary in name:

//*[*/title = "50"]

Or, in name and depth:

//*[.//title = "50"]

Attributions

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Content TypeOriginal AuthorOriginal Content on Stackoverflow
QuestionGibboKView Question on Stackoverflow
Solution 1 - XmlRené LinkView Answer on Stackoverflow
Solution 2 - XmlAminah NurainiView Answer on Stackoverflow
Solution 3 - XmlphduarteView Answer on Stackoverflow
Solution 4 - XmlkjhughesView Answer on Stackoverflow