Saxon » SaxonC

Please indicate what steps are needed to reproduce the problem.

The error message: Error reported by XML parser: Content is not allowed in prolog.: Content is not allowed in prolog. appears when attempting to transform with the Saxonche 12.3.0 using

xsltProc.transform_to_file(source_file=source, stylesheet_file=xslt, output_file=result)

The source_file=source parameter refers to a file directory with several XML documents inside. This error does not exist for Saxonche 12.0.0.

Checked out the latest code from your GitHub project. Now getting the result:

python XMLDataPull.py
SaxonC-HE 12.3 from Saxonica
<?xml version="1.0" encoding="UTF-8"?>
<root>
   <metadata>
      <machName>Spotify</machName>
      <time>2023-07-06T18:39:40.9903796-04:00</time>
   </metadata>
   <data>
      <cd num="1"
           artist="Bob Dylan"
           title="Empire Burlesque"
           sequence="1"
           year="1985">10.90</cd>
      <cd num="2"
           artist="Garg Moore"
           title="Still got the blues"
           sequence="2"
           year="1990">10.20</cd>
      <cd num="3"
           artist="Eros Ramazzotti"
           title="Eros"
           sequence="3"
           year="1997">9.90</cd>
      <cd num="4"
           artist="Dolly Parton"
           title="Greatest Hits"
           sequence="4"
           year="1982">9.90</cd>
      <cd num="5"
           artist="Bonnie Tyler"
           title="Hide your heart"
           sequence="5"
           year="1988">9.90</cd>
   </data>
</root>

miniDom parsing:  <xml.dom.minidom.Document object at 0x107873580>
<?xml version="1.0" encoding="UTF-8"?>
<root>
   <metadata>
      <machName>Youtube</machName>
      <time>2023-07-06T18:39:40.9903796-04:00</time>
   </metadata>
   <data>
      <cd num="1"
           artist="Bob Dylan"
           title="Empire Burlesque"
           sequence="1"
           year="1985">10.90</cd>
      <cd num="2"
           artist="Garg Moore"
           title="Still got the blues"
           sequence="2"
           year="1990">10.20</cd>
      <cd num="3"
           artist="Eros Ramazzotti"
           title="Eros"
           sequence="3"
           year="1997">9.90</cd>
      <cd num="4"
           artist="Dolly Parton"
           title="Greatest Hits"
           sequence="4"
           year="1982">9.90</cd>
      <cd num="5"
           artist="Bonnie Tyler"
           title="Hide your heart"
           sequence="5"
           year="1988">9.90</cd>
   </data>
</root>

miniDom parsing:  <xml.dom.minidom.Document object at 0x107884a60>

My suggestion still would be to use an initial template, no source document and then call_template..., also to ensure the result files created with xsl:result-document in a subdirectory it is necessary to set the base_output_uri, in my opinion easiest done with the help of pathlib e.g.

from saxonche import PySaxonProcessor

from pathlib import Path

with PySaxonProcessor(license=False) as proc:
	print(proc.version)
	xsltproc = proc.new_xslt30_processor()
	source = "data"
	xslt = "DataXSLT.xsl"
	result = "output"
	base_output_uri = Path('.', result, 'result').absolute().as_uri()
	#print(base_output_uri)
	xslt_executable = xsltproc.compile_stylesheet(stylesheet_file=xslt)
	xslt_executable.call_template_returning_value(template_name=None, base_output_uri=base_output_uri)

and the XSLT having e.g.

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    exclude-result-prefixes="#all"
    version="3.0">

    <xsl:variable name="dataColl" as="document-node()+" select="collection('data/?select=*.xml')"/>

    <xsl:template name="xsl:initial-template" match="/">
        <xsl:for-each select="$dataColl">
            <xsl:result-document href="{//DeviceStream/@name}.xml" method="xml" indent="yes">
                <root>
                    <metadata>
                        <machName>
                            <xsl:value-of
                                select="//DeviceStream[not(@name = 'Agent')]/@name"/>
                        </machName>
                        <time>
                            <xsl:value-of select="current-dateTime()"/>
                        </time>
                    </metadata>
                    <data>
                        <xsl:for-each select="//*[@sequence]">
                            <xsl:sort select="xs:integer(@sequence)"/>
                            <xsl:copy>
                                <xsl:attribute name="num" select="@sequence"/>
                                <xsl:copy-of select="@*, node()"/>
                            </xsl:copy>
                        </xsl:for-each>
                    </data>
                </root>
            </xsl:result-document>
        </xsl:for-each>
    </xsl:template>

</xsl:stylesheet>

Thanks Martin for your suggestion. Yes that would work. Just to add, William may find also useful to capture the result documents using SaxonC for further processing. They are represented as a dict object [URI, PyXdmValue] with the URI as the document uri and the PyXdmValue as the secondary result documents. For example:

from saxonche import PySaxonProcessor

from pathlib import Path

with PySaxonProcessor(license=False) as proc:
	print(proc.version)
	xsltproc = proc.new_xslt30_processor()
	source = "data"
	xslt = "DataXSLT.xsl"
	result = "output"
	base_output_uri = Path('.', result, 'result').absolute().as_uri()
	#print(base_output_uri)
	xslt_executable = xsltproc.compile_stylesheet(stylesheet_file=xslt)
        xslt_excutable.set_capture_result_documents(True)
	result = xslt_executable.call_template_returning_value(template_name=None, base_output_uri=base_output_uri)
        result_documents = xslt_executable.get_result_documents()
        print(*self.result_documents, sep=", ")

Hi O'Neill and Michael. I don't think the problem is with generating output. It is simply with reading input and launching the XSLT. That is, I do not think we need to change the structure of the XSLT document, and we're already set with xsl:result-document to output files as we want to.

The issue is simply the function running the XSLT in the first place.

On Windows 10 and 11 (two different machines) we have this problem:

In saxonche 12.3, 12.2, and 12.1 on Windows systems: The XSLT does not run when we use this format of transform_to_file()

xsltproc.transform_to_file(stylesheet_file=xslt, output_file=result)  

If we specify an input this, fails with the original posted error ("Content not allowed in prolog").

We downgraded to saxonch 12.0 and we find this:

1. The XSLT does not run when we use:

xsltproc.transform_to_file(stylesheet_file=xslt, output_file=result)  

2. The XSLT does run successfully and populate the output directory properly etc, but we MUST specify a source file in 12.0

This works and it's the only thing that has worked on Windows:

xsltProc.transform_to_file(source_file=source, stylesheet_file=xslt, output_file=result)

Just a quick update to specify that in the line that works for us on Windows, the following are variables that store relative filepaths:

• source
• xslt
• result

Is source supposed to be an XML document to be processed? Or a directory?

Are you running that code with Saxon from the command line providing -s or in oXygen naming an input document?

Still don't understand what source is supposed to be needed for or the the initial match="/" because inside the only code is <xsl:for-each select="$dataColl">..</xsl:for-each> which does not use any XML input document or context node or context item at all. That's why I simply think using a named template and starting with it is more adequate in the context of XSLT 2 or 3 or with any version and platform Saxon exists for.

That in some case SaxonC with transform_to_file and source_file=source where source is a directory worked out is in my view more a quirk or bug of that particular Saxon version than a reasonable result to expect.

But let's see what Saxonica thinks, my suggestion to use a different method in the API and a slight change in the stylesheet ( (i.e. start with a named template) was meant to allow you to get consistent results (hopefully, admittedly I only tested with 12.3) and not to rely on a quirk of 12.something that has gone away in the current release.

Thank you all for the help. I managed to replicate Martin's and O'Neil's scripts successfully with SaxonC 12.3. I've created a named template in the XSLT following Martin's suggestion and now use call_template_returning_value() instead of transform_to_file(). My current script successfully outputs transformed XML. I'll update the repo I supplied with the solution soon.