XSLT: reading value of field and creating elements in a loop

Question

this might be a simple question but I just started with xslt and i cant get it to work.

Basically I got an xml with this format coming in:

<?xml version="1.0" encoding="UTF-8"?> 
<FileXML xmlns:vi="http://www.w3.org/1999/XSL/Transform" xmlns="http://www.w3.org/1999/XSL/Transform"> 
    <vi:Branch> 
        <vi:Identifier>81388</vi:Identifier> 
        <vi:Name>Union Square Limited</vi:Name> 
        <vi:BranchInformation> 
            <vi:BranchInformation> 
                <vi:Employees>3</vi:Employees> 
            </vi:BranchInformation> 
        </vi:BranchInformation> 
    </vi:Branch> 
</FileXML>

What I am trying to achieve is an output like:

<?xml version="1.0" encoding="UTF-8"?> 
<FileXML xmlns:vi="http://www.w3.org/1999/XSL/Transform" xmlns="http://www.w3.org/1999/XSL/Transform"> 
<vi:Branch> 
    <vi:Identifier>81388-1</vi:Identifier> 
    <vi:Name>Union Square Limited</vi:Name> 
    <vi:BranchInformation> 
        <vi:BranchInformation> 
            <vi:Employees>1</vi:Employees> 
        </vi:BranchInformation> 
    </vi:BranchInformation> 
</vi:Branch> 
<vi:Branch> 
    <vi:Identifier>81388-2</vi:Identifier> 
    <vi:Name>Union Square Limited</vi:Name> 
    <vi:BranchInformation> 
        <vi:BranchInformation> 
            <vi:Employees>1</vi:Employees> 
        </vi:BranchInformation> 
    </vi:BranchInformation> 
</vi:Branch> 
<vi:Branch> 
    <vi:Identifier>81388-3</vi:Identifier> 
   <vi:Name>Union Square Limited</vi:Name> 
    <vi:BranchInformation> 
        <vi:BranchInformation> 
            <vi:Employees>1</vi:Employees> 
        </vi:BranchInformation> 
    </vi:BranchInformation> 
</vi:Branch> 
</FileXML>

This means it should read the amount of employees (=3) in the source xml and therefore create three Branch elements with all the original data but assign a unique Identifier. I think I can manage to change the Employees to have the value 1 afterwards but the rest is totally above my current skills.

Any thoughts or ideas are more than welcome! Thanks!

May I ask *why* would you want to do this? In general, one would want to *eliminate* redundant repetition of data, not *create* it. — michael.hor257k, Dec 30 '13 at 13:33
Why is the input data using the namespace `http://www.w3.org/1999/XSL/Transform` which is the namespace of the W3C XSLT language? And speaking about the language, which version do you want to use, can you use version 2.0 which has the XPath `to` operator? — Martin Honnen, Dec 30 '13 at 13:35

Mathias Müller · Accepted Answer · 2013-12-30T13:45:29.770

The following XSLT stylesheet does what you need. It uses XSLT 2.0 since you did not say what version is at your disposal.

As long as the branch has only 1 employee, it performs a common identity transform. If this is not the case, a named template make-branch is called, that recursively generates vi:Branch elements for all employees.

<?xml version="1.0" encoding="utf-8"?>

<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:vi="http://www.vi.org/vi">

<xsl:output method="xml" indent="yes"/>

<xsl:template match="@*|node()">
  <xsl:copy>
     <xsl:apply-templates select="@*|node()"/>
  </xsl:copy>
</xsl:template>

<xsl:template match="vi:Branch[number(vi:BranchInformation/vi:BranchInformation/vi:Employees) gt 1]">
  <xsl:call-template name="make-branch"/>
</xsl:template>

<xsl:template name="make-branch">
  <xsl:param name="emp" select="1"/>

  <vi:Branch>
     <vi:Identifier>
        <xsl:value-of select="concat(vi:Identifier,'-',$emp)"/>
     </vi:Identifier>
     <xsl:copy-of select="vi:Name"/>
     <vi:BranchInformation>
        <vi:Employees>1</vi:Employees>
     </vi:BranchInformation>
  </vi:Branch>

  <xsl:choose>
     <xsl:when test="$emp lt number(vi:BranchInformation/vi:BranchInformation/vi:Employees)">
        <xsl:call-template name="make-branch">
           <xsl:with-param name="emp" select="$emp + 1"/>
        </xsl:call-template>
     </xsl:when>
     <xsl:otherwise/>
  </xsl:choose>
</xsl:template>

</xsl:stylesheet>

Applied on the input as follows. It is slightly different from yours, as you can see, I have changed the namespace declaration of xmlns:vi.

<?xml version="1.0" encoding="UTF-8"?> 
<FileXML  xmlns:vi="http://www.vi.org/vi" xmlns="http://www.w3.org/1999/XSL/Transform"> 
 <vi:Branch> 
    <vi:Identifier>81388</vi:Identifier> 
    <vi:Name>Union Square Limited</vi:Name> 
    <vi:BranchInformation> 
        <vi:BranchInformation> 
            <vi:Employees>3</vi:Employees> 
        </vi:BranchInformation> 
    </vi:BranchInformation> 
 </vi:Branch> 
</FileXML>

Gives the following output, I have eliminated a redundant vi:BranchInformation element:

<?xml version="1.0" encoding="UTF-8"?>
<FileXML xmlns:vi="http://www.vi.org/vi" xmlns="http://www.w3.org/1999/XSL/Transform"> 
 <vi:Branch>
  <vi:Identifier>81388-1</vi:Identifier>
  <vi:Name>Union Square Limited</vi:Name>
  <vi:BranchInformation>
     <vi:Employees>1</vi:Employees>
  </vi:BranchInformation>
 </vi:Branch>
 <vi:Branch>
  <vi:Identifier>81388-2</vi:Identifier>
  <vi:Name>Union Square Limited</vi:Name>
  <vi:BranchInformation>
     <vi:Employees>1</vi:Employees>
  </vi:BranchInformation>
 </vi:Branch>
 <vi:Branch>
  <vi:Identifier>81388-3</vi:Identifier>
  <vi:Name>Union Square Limited</vi:Name>
  <vi:BranchInformation>
     <vi:Employees>1</vi:Employees>
  </vi:BranchInformation>
 </vi:Branch> 
</FileXML>

However, it is doubtful whether this transformation actually helps structuring your data. Perhaps, it is rather detrimental to that.

Great stuff. Thank you so much. I hope I can learn how to do this by myself. :) Quick question. Why cant I change the namespace for vi to anything else? If I do so the result file will just be the source file again. — user3146479, Dec 30 '13 at 14:05
The explanation depends on _where_ you "change the namespace", in the input XML or in the XSLT stylesheet? Perhaps I have answered your question elsewhere already: http://stackoverflow.com/questions/20679790/need-of-namespace-in-xml/20680122#20680122. — Mathias Müller, Dec 30 '13 at 14:38
argh, thanks Mathias. I am such an idiot. Just changed the namespace in the stylesheet. Works fine now. ;) Just noticed the " gt 1]" in the template-match. What is it used for? — user3146479, Dec 30 '13 at 14:44
Now, this is really something you could find out yourself - simply google it. But since I'm writing anyway: it means "greater than" and performs a comparison. — Mathias Müller, Dec 30 '13 at 14:46
I shouldnt fall into the habit and get too lazy. You are absolutely right! Thanks for your answer and patience! :) — user3146479, Dec 30 '13 at 14:53

XSLT: reading value of field and creating elements in a loop

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