如何使用XSLT去除XML节点中的重复值？

Hey there! To get rid of duplicate <item> nodes in your XML, the Muenchian Grouping technique is the tried-and-true approach in XSLT—it’s efficient and works with almost all XSLT processors out there.

First, let’s clarify: I’ll assume you want to flag an <item> as duplicate if all its child values (PLANT, SLOC, MATNR, CHARG) are identical. If you need to group by a subset of fields (like only MATNR + PLANT), you can tweak the solution easily.

Full XSLT Solution #

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <!-- Define a key to group items by their unique field combination -->
    <xsl:key 
        name="uniqueItem" 
        match="item" 
        use="concat(PLANT, '|', SLOC, '|', MATNR, '|', CHARG)" 
    />

    <!-- Identity template: copies all nodes/attributes by default -->
    <xsl:template match="@* | node()">
        <xsl:copy>
            <xsl:apply-templates select="@* | node()"/>
        </xsl:copy>
    </xsl:template>

    <!-- Remove duplicate items: only keep the first occurrence in each group -->
    <xsl:template match="item[not(generate-id() = generate-id(key('uniqueItem', concat(PLANT, '|', SLOC, '|', MATNR, '|', CHARG))[1]))]"/>
</xsl:stylesheet>

How This Works #

• Key Definition: The uniqueItem key groups <item> nodes using a concatenated string of their child values. The | separator prevents accidental collisions (e.g., avoiding confusion between "INDIA150" and "INDIA" + "150").
• Identity Template: This preserves your original XML structure—everything gets copied unless we explicitly override it.
• Duplicate Removal: The final template matches any <item> that isn’t the first entry in its key group, and does nothing with it (so it gets excluded from the output).

Adjusting for Partial Field Grouping #

If you only want to remove duplicates based on a subset of fields (say, PLANT and MATNR), just update the key and match condition:

<xsl:key 
    name="uniqueItem" 
    match="item" 
    use="concat(PLANT, '|', MATNR)" 
/>

<xsl:template match="item[not(generate-id() = generate-id(key('uniqueItem', concat(PLANT, '|', MATNR))[1]))]"/>

When you run this XSLT against your sample XML, you’ll end up with only one <item> per unique combination of the fields you specified.

内容的提问来源于stack exchange，提问作者Soham Shah