Question

I am trying to call a static Java method from my XSLT stylesheet:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                              xmlns:digest="java:org.apache.commons.codec.digest.DigestUtils">
<xsl:output method="xml" encoding="utf-8" indent="yes"/>

<xsl:template match="user">
  <user>
    <firstname>
      <xsl:value-of select="value[@type='firstname'][1]" />
    </firstname>
    <lastname>
      <xsl:value-of select="value[@type='name'][1]" />
    </lastname>
    <password>
      <xsl:variable name="password" select="string(value[@type='password'][1])" />
      <xsl:value-of select="digest:md5Hex($password)"
                    disable-output-escaping="yes" />
    </password>
  </user>
</xsl:template>

The DigestUtils class is found and the static md5Hex-method [1] as well. The problem is, that there are three possible ways to invoke the method, namely with a byte[], an InputStream or a String. Given that the “password” variable is of type xs:string, I assumed that Saxon would automatically choose the last option. But instead, it insists on the byte[]-method and fails accordingly:

[...]
Loading org.apache.commons.codec.digest.DigestUtils
Looking for method md5Hex in Java class class org.apache.commons.codec.digest.DigestUtils
Number of actual arguments = 1
[...]
Trying method md5Hex: name matches
Method is static
Method has 1 argument; expecting 1
Found a candidate method:
    public static java.lang.String org.apache.commons.codec.digest.DigestUtils.md5Hex(byte[])
Trying method md5Hex: name matches
Method is static
Method has 1 argument; expecting 1
Found a candidate method:
    public static java.lang.String org.apache.commons.codec.digest.DigestUtils.md5Hex(java.io.InputStream) throws java.io.IOException
Trying method md5Hex: name matches
Method is static
Method has 1 argument; expecting 1
Found a candidate method:
    public static java.lang.String org.apache.commons.codec.digest.DigestUtils.md5Hex(java.lang.String)
[...]
Finding best fit method for arguments
Trying option 0: public static java.lang.String org.apache.commons.codec.digest.DigestUtils.md5Hex(byte[])
Conversion preferences are [24]
Trying option 1: public static java.lang.String    org.apache.commons.codec.digest.DigestUtils.md5Hex(java.io.InputStream) throws java.io.IOException
Conversion preferences are [80]
Trying option 2: public static java.lang.String org.apache.commons.codec.digest.DigestUtils.md5Hex(java.lang.String)
Conversion preferences are [80]
Eliminating option 1
Eliminating option 2
Number of candidate methods remaining: 1
Error at xsl:template on line 14 column 30 of migrate_users.xsl:
  Cannot convert from xs:string to byte
Failed to compile stylesheet. 1 error detected.

Is there a way to force Saxon to use the String-method?

[1] http://commons.apache.org/codec/api-release/org/apache/commons/codec/digest/DigestUtils.html#md5Hex(java.lang.String)

—
update: A colleague just found the company’s license key for Saxon 9.4PE. Unfortunately the error persists, the only thing that changed was that the conversion preference for the byte[]-method went from 24 to 31.

Answer 1

You need to type your variable:

<xsl:variable as="xs:string" name="password" select="string(value[@type='password'][1])" />

or cast it in the call:

<xsl:value-of select="digest:md5Hex(xs:string($password))"
                disable-output-escaping="yes" />

With the xs namespace defined as:

xmlns:xs="http://www.w3.org/2001/XMLSchema"