XSLT sort parent nodes based on maximum child node

Question

I've looked through all existing articles about XSLT sorting, but still can't figure out a proper decision for my sorting case. I need to sort child nodes firstly (descending order) and then sort parent nodes (descending order) based on first (maximum) child value.

So, I need final order Name3, Name1, Name2, but I have Name1, Name3, Name2.

Could you please help to find a solution. Thanks in advance!

Input xml:

<collection>
<products>
    <product>
        <productCode>001</productCode>
        <productName>Name1</productName>
        <subProducts>
            <subProduct>
                <prices>
                    <price>
                        <totalPrice>264.28</totalPrice>
                    </price>                    
                </prices>
            </subProduct>
            <subProduct>
                <prices>
                    <price>
                        <totalPrice>264.28</totalPrice>
                    </price>
                </prices>
            </subProduct>                               
        </subProducts>
    </product>
    <product>
        <productCode>002</productCode>
        <productName>Name2</productName>
        <subProducts>
            <subProduct>
                <prices>
                    <price>
                        <totalPrice>231.99</totalPrice>
                    </price>
                    <price>
                        <totalPrice>231.99</totalPrice>
                    </price>
                </prices>
            </subProduct>
            <subProduct>
                <prices>
                    <price>
                        <totalPrice>231.99</totalPrice>
                    </price>
                    <price>
                        <totalPrice>231.99</totalPrice>
                    </price>
                </prices>
            </subProduct>                           
        </subProducts>
    </product>
    <product>
        <productCode>003</productCode>
        <productName>Name3</productName>
        <subProducts>
            <subProduct>
                <prices>
                    <price>
                        <totalPrice>234.92</totalPrice>
                    </price>
                </prices>
            </subProduct>   
            <subProduct>
                <prices>
                    <price>
                        <totalPrice>734.12</totalPrice>
                    </price>                    
                </prices>
            </subProduct>                           
        </subProducts>
    </product>          
</products>
</collection>

Output xml: (Expected)

<products>
<product>
    <productName>Name3</productName>
    <price>734.12</price>
    <price>234.92</price>
</product>
<product>
    <productName>Name1</productName>
    <price>264.28</price>
    <price>264.28</price>
</product>
<product>
    <productName>Name2</productName>
    <price>231.99</price>
    <price>231.99</price>
    <price>231.99</price>
    <price>231.99</price>
</product>
</products>

XSLT transformation:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
    <xsl:copy>
        <xsl:apply-templates select="/collection/products/product"> 
            <xsl:sort select="subProducts/subProduct[1]/prices/price[1]/totalPrice" data-type="number" order="descending"/>             
        </xsl:apply-templates>          
    </xsl:copy>
</xsl:template>

<xsl:template match="/collection/products/product">     
    <xsl:copy>          
        <productName>
            <xsl:value-of select="productName"/>
        </productName>          
        <xsl:apply-templates select="subProducts/subProduct/prices/price">
            <xsl:sort select="totalPrice" order="descending" data-type="number"/>
        </xsl:apply-templates>          
    </xsl:copy>
</xsl:template>

<xsl:template match="subProducts/subProduct/prices/price">
    <xsl:copy>
        <xsl:value-of select="totalPrice"/>
    </xsl:copy>
</xsl:template>
</xsl:stylesheet>

Wrong xml output:

 <products>
<product>
    <productName>Name1</productName>
    <price>264.28</price>
    <price>264.28</price>
</product>
<product>
    <productName>Name3</productName>
    <price>734.12</price>
    <price>234.92</price>
</product>
<product>
    <productName>Name2</productName>
    <price>231.99</price>
    <price>231.99</price>
    <price>231.99</price>
    <price>231.99</price>
</product>
</products>

Which XSLT processor will you be using? In pure XSLT 1.0, with no extensions support, you will have to do this in two passes. — michael.hor257k

michael.hor257k michael.hor257k · Accepted Answer · 2017-04-07T15:23:39

If you're using the Xalan processor, you can take advantage of the EXSLT math:max() extension function:

XSLT 1.0

<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:math="http://exslt.org/math"
extension-element-prefixes="math">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:strip-space elements="*"/>

<xsl:template match="/">
    <products>
        <xsl:apply-templates select="collection/products/product"> 
            <xsl:sort select="math:max(subProducts/subProduct/prices/price/totalPrice)" data-type="number" order="descending"/>             
        </xsl:apply-templates>          
    </products>
</xsl:template>

<xsl:template match="product">     
    <xsl:copy>          
        <xsl:copy-of select="productName"/>
        <xsl:apply-templates select="subProducts/subProduct/prices/price">
            <xsl:sort select="totalPrice" data-type="number" order="descending"/>
        </xsl:apply-templates>          
    </xsl:copy>
</xsl:template>

<xsl:template match="price">
    <xsl:copy>
        <xsl:value-of select="totalPrice"/>
    </xsl:copy>
</xsl:template>

</xsl:stylesheet>

Demo: http://xsltransform.net/3Mvmrzh/1

XSLT sort parent nodes based on maximum child node

1 Answers