Getting unique XPath node values in nested nodes

Question

I'm a bit of a newbie to XPath, so I need some help figuring this out. I have an XML file like so:

<items>
    <item>
        <brandName>Brand 1</brandName>
        <productTypes>
            <productType>Type 1</productType>
            <productType>Type 3</productType>
        </productTypes>
    </item>
    <item>
        <brandName>Brand 1</brandName>
        <productTypes>
            <productType>Type 2</productType>
            <productType>Type 3</productType>
        </productTypes>
    </item>
    <item>
        <brandName>Brand 2</brandName>
        <productTypes>
            <productType>Type 4</productType>
            <productType>Type 5</productType>
        </productTypes>
    </item>
</items>

I'm trying to figure out a way of getting all of the unique productType's for a specific brand. For example, all of the unique productType's for "Brand 1" would output "Type 1", "Type 2", "Type 3"

I've been googling without much luck. Any help would be appreciated!

I don't think you can perform a unique operation on a node set xpath expression, you'll need some extra code in whatever language you are using to parse the expression. — jspboix
– jspboix, Commented Jun 19, 2012 at 17:29

AlbertFerras · Accepted Answer · 2012-06-19 17:37:33Z

3

This works:

(/items/item[brandName='Brand 1']/productTypes/productType)[not(text()=preceding::*)]

How it works: The first (...) gets all the productType of brandName='Brand 1'. At this point I have a list of productType nodes. Now I select the nodes where the node text is not contained in nodes preceding the current node.

Tried in python:

n = libxml2dom.parseString(xml)
[x.textContent for x in n.xpath("(/items/item[brandName='Brand 1']/productTypes/productType)[not(text()=preceding::*)]")]
>>> [u'Type 1', u'Type 3', u'Type 2']

answered Jun 19, 2012 at 17:37

AlbertFerras

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