Python API for SaxonC-HE fails when creating XDM dict with string values

I am using SaxonC-HE 12.5 to apply an XSL 3.0 transformation in a Python 3.10 application. The XSL stylesheet takes a parameter that is a map of string -> string, as follows:

<xsl:param name="myMapParam" as="map(xs:string, xs:string)">

To build this map, I am using the create_xdm_dict() static method from saxonche to convert a Python dict to an XDM dict, then use this XDM dict as input to the make_map() method in PySaxonProcessor to create a map that I can pass as a parameter into the transformation:

from saxonche import *

with PySaxonProcessor(license=False) as saxonproc:

    dict = {"a": saxonproc.make_string_value("jack"),
            "b": saxonproc.make_string_value("jill")}

    xdm_dict = create_xdm_dict(saxonproc, dict)
    map = saxonproc.make_map(xdm_dict)

In fact, this code is almost exactly like that in the SaxonC documentation, except that the values in the dict are strings, not numbers.

When I attempt this, Saxon fails in the create_xdm_dict() method with a java.lang.NumberFormatException because it looks like it tries to convert the values into numbers (Doubles, to be precise) even though I explicitly asked to make string values:

java.lang.NumberFormatException: For input string: "jack"
    at jdk.internal.math.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:2054)
    at jdk.internal.math.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
    at java.lang.Double.parseDouble(Double.java:543)
    at net.sf.saxon.type.StringToDouble.stringToNumber(StringToDouble.java:178)
    at net.sf.saxon.s9api.XdmAtomicValue.getLongValue(XdmAtomicValue.java:454)
    at net.sf.saxon.option.cpp.XdmValueForCpp.getLongValue(XdmValueForCpp.java:235)

Any guidance on how to create an XDM map with string values would be much appreciated. Thank you!

Solution

The dictionary keys also have to be created as XDM strings with saxon_processor.make_string_value e.g.

from saxonche import *

with PySaxonProcessor() as saxon_proc:
    print(saxon_proc.version)

    python_dic = { 'a' : 'foo', 'b' : 'bar' }

    xdm_map = saxon_proc.make_map({saxon_proc.make_string_value(key) : saxon_proc.make_string_value(value) for key, value in python_dic.items()})

    print(xdm_map)

    xpath_proc = saxon_proc.new_xpath_processor()

    xpath_proc.declare_variable('map1')

    xpath_proc.set_parameter('map1', xdm_map)

    print(xpath_proc.evaluate_single('$map1?a'))

    xslt_executable = saxon_proc.new_xslt30_processor().compile_stylesheet(stylesheet_file='sheet1.xsl')

    xslt_executable.set_parameter('map1', xdm_map)

    print(xslt_executable.call_template_returning_string())

gives

SaxonC-HE 12.5 from Saxonica
map{"a":"foo","b":"bar"}
foo
foo

with e.g. sample XSLT being

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

  <xsl:param name="map1" as="map(xs:string, xs:string)" required="yes"/>

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

  <xsl:template match="/" name="xsl:initial-template">
      <xsl:sequence select="$map1?a"/>
  </xsl:template>

</xsl:stylesheet>