Question

I have a xml document, now i want to translate it to another xml document with same content but different element orders.

The original xml document like:

<?xml version = "1.0" encoding = "UTF-8"?>  
<order xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance" >  
 <ship>  
    <zipcode>78712</zipcode>  
    <street>1234 Main Street</street>  
    <country>CN</country>    
    <city>Beijing</city>  
 </ship>   
 <items>     
    <quantity>1</quantity>     
    <itemno>1234</itemno>  
 </items>     
 <items>     
    <quantity>3</quantity>    
    <itemno>1235</itemno>    
 </items>    
 <price>456</price>  
 <customer>Tom Hill</customer>    
</order>  

The expected output xml document like:

<?xml version = "1.0" encoding = "UTF-8"?>  
<order xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance" >  
 <customer>Tom Hill</customer>    
 <ship>  
    <street>1234 Main Street</street>  
    <city>Beijing</city>  
    <zipcode>78712</zipcode>  
    <country>CN</country>    
 </ship>    
 <items>     
    <itemno>1234</itemno>    
    <quantity>1</quantity>     
 </items>     
 <items>     
    <itemno>1235</itemno>    
    <quantity>3</quantity>    
 </items>    
 <price>456</price>  
</order> 

I used following xslt document to translate it.

<?xml version="1.0"?>  
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">  
<xsl:template match="/order">  
 <xsl:copy>  
  <xsl:copy-of select="customer" />  
  <xsl:copy-of select="ship" >  
  <xsl:call-template name="TShip" />  
  </xsl:copy-of>  
  <xsl:copy-of select="items">  
  <xsl:call-template name="TItems" />  
  </xsl:copy-of>  
 <xsl:copy-of select="price" />  
 </xsl:copy>  
</xsl:template>  

<xsl:template name="TShip">  
 <xsl:copy>  
  <xsl:copy-of select="street" />  
  <xsl:copy-of select="city" />  
  <xsl:copy-of select="zipcode" />  
  <xsl:copy-of select="country" />  
 </xsl:copy>  
</xsl:template>  

<xsl:template name="TItems">  
 <xsl:for-each select="items">  
  <xsl:copy>  
   <xsl:copy-of select="itemno" />  
   <xsl:copy-of select="quantity" />  
  </xsl:copy>  
 </xsl:for-each>  
</xsl:template>  

</xsl:stylesheet>  

However, the translated result is not my expected.
Translated result xml:

<?xml version = "1.0" encoding = "UTF-8"?>  
<order xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance" >  
 <customer>Tom Hill</customer>    
 <ship>  
    <zipcode>78712</zipcode>  
    <street>1234 Main Street</street>  
    <country>CN</country>    
    <city>Beijing</city>    
 </ship>    
 <items>     
    <quantity>1</quantity>     
    <itemno>1234</itemno>    
 </items>     
 <items>     
    <quantity>3</quantity>    
    <itemno>1235</itemno>   
 </items>    
 <price>456</price>  
</order>  

It just made the first level nodes in expected order. All sub-nodes are kept in original order. How can i make the order of all nodes as my expected ?

Answer 1

xsl:copy-of copies all child nodes as well and child nodes of it are not evaluated.

So your TShip and TItems templates are never even being evaluated. <xsl:copy-of select="ship"> copies all of <ship>...</ship>.

This modification to your template will demonstrate that your TShip and TItems templates are not being called.

<?xml version="1.0"?>  
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">  
<xsl:template match="/order">  
 <xsl:copy>  
  <xsl:copy-of select="customer" />
    <xsl:copy-of select="ship">
  <xsl:call-template name="TShip" />  
</xsl:copy-of>
  <xsl:copy-of select="items">  
  <xsl:call-template name="TItems" />  
  </xsl:copy-of>  
 <xsl:copy-of select="price" />  
 </xsl:copy>  
</xsl:template>  

<xsl:template name="TShip">  
 <xsl:copy>  
  <test>TShip called</test>
  <xsl:copy-of select="street" />  
  <xsl:copy-of select="city" />  
  <xsl:copy-of select="zipcode" />  
  <xsl:copy-of select="country" />  
 </xsl:copy>  
</xsl:template>  

<xsl:template name="TItems">  
 <xsl:for-each select="items">  
  <xsl:copy> 
  <test>TItems called</test>
   <xsl:copy-of select="itemno" />  
   <xsl:copy-of select="quantity" />  
  </xsl:copy>  
 </xsl:for-each>  
</xsl:template>  

</xsl:stylesheet>

Notice that the output does not contain the <test> elements I added.

What you need to do instead is recursive implicit copying. Usually xsl:copy, xsl:copy-of and xsl:for-each are a sign of bad xsl template design–there are very few problems which xsl:template and xsl:apply-template with an identity transform do not handle better.

This is how I would do it:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    <xsl:output encoding="UTF-8" indent="yes" method="xml" />

    <xsl:template match="order">
        <xsl:copy>
            <!-- copy all attributes; maybe you don't want this -->
            <xsl:apply-templates select="@*" />
            <!-- copy some elements in a specific order  -->
            <xsl:apply-templates select="customer" />
            <xsl:apply-templates select="ship" />
            <xsl:apply-templates select="items" />
            <xsl:apply-templates select="price" />
            <!-- now copy any other children that we haven't explicitly reordered; again, possibly this is not what you want -->
            <xsl:apply-templates select="*[not(self::customer or self::ship or self::items or self::price)]"/>
        </xsl:copy>
    </xsl:template>

    <xsl:template match="ship">
        <xsl:copy>
            <xsl:apply-templates select="@*" />
            <xsl:apply-templates select="street" />
            <xsl:apply-templates select="city" />
            <xsl:apply-templates select="zipcode" />
            <xsl:apply-templates select="country" />
            <xsl:apply-templates select="*[not(self::street or self::city or self::zipcode or self::country)]"/>
        </xsl:copy>
    </xsl:template>

    <xsl:template match="items">
        <xsl:copy>
            <xsl:apply-templates select="@*" />
            <xsl:apply-templates select="itemno" />
            <xsl:apply-templates select="quantity" />
            <xsl:apply-templates select="*[not(self::itemno or self::quantity)]"/>
        </xsl:copy>
    </xsl:template>

    <!-- this is the identity transform: it copies everything that isn't matched by a more specific template -->
    <xsl:template match="@*|node()">
        <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
        </xsl:copy>
    </xsl:template>

</xsl:stylesheet>

Notice how many fewer assumptions this template design makes about the structure of your source XML. It is also much easier to change: for example, if you want to silence or rename a particular element that may itself have children, you just add a new xsl:template that matches that element, do whatever you need to do, and xsl:apply-templates on the children.

You should learn more about this XSLT pattern because it is very versatile and makes template authoring much less tedious and your templates much less brittle.