lxml Create XML file recursively based on another XML File

Question

My goal is to Recursively create an XML File based on another XML File.
Sample Input Data as below (Original Files are ~ 10MB)

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<Picture Name="Template">
  <Children>
    <Shape Name="GroupLevel" ClassName="Group">
      <Properties>
        <Property Name="Property1" Value="Value1" />
        <Property Name="Property2" Value="Value2" />
        <Property Name="Property3" Value="Value3" />
      </Properties>
      <ContainedObjects>
        <Shape Name="Group1" ClassName="Group">
          <Properties>
            <Property Name="Property1" Value="Value1" />
            <Property Name="Property2" Value="Value2" />
            <Property Name="Property3" Value="Value3" />
          </Properties>
          <ContainedObjects>
            <Shape Name="Glue123" ClassName="Text" />
            <Shape Name="Variable1" ClassName="Variable" />
            <Shape Name="Variable2" ClassName="Variable" />
            <Shape Name="Variable3" ClassName="Variable" />
            <Shape Name="Group2" ClassName="Group">
              <Properties>
                <Property Name="Property1" Value="Value1" />
                <Property Name="Property2" Value="Value2" />
                <Property Name="Property3" Value="Value3" />
              </Properties>
              <ContainedObjects>
                <Shape Name="Group3" ClassName="RoundRect" />
              </ContainedObjects>
            </Shape>
          </ContainedObjects>
        </Shape>
      </ContainedObjects>
    </Shape>
  </Children>
</Picture>

Need to Loop Inside Child tag. During the Loop, if I find the Shape tag Whose Parent is Children, Create a Node with that Tag Name in a blank Root.
Ignore Properties / Property Nodes
If I find Shape tag Whose Parent is ContainedObjects, Create a Node ContainedObjects while maintaining the depth, add the Shape Tag Inside that ContainedObjects Node.
The actual operations involve creating a Different set of Nodes based on each Shape Tag, Which will be done at a later stage.
For now, I am stuck at the recursive looping.

<Children>
  <Shape Name="GroupLevel" ClassName="Group">
    <ContainedObjects>
      <Shape Name="Group1" ClassName="Group">
        <ContainedObjects>
          <Shape Name="Glue123" ClassName="Text" />
          <Shape Name="Variable1" ClassName="Variable" />
          <Shape Name="Variable2" ClassName="Variable" />
          <Shape Name="Variable3" ClassName="Variable" />
          <Shape Name="Group2" ClassName="Group">
            <ContainedObjects>
              <Shape Name="Group3" ClassName="RoundRect" />
            </ContainedObjects>
          </Shape>
        </ContainedObjects>
      </Shape>
    </ContainedObjects>
  </Shape>
</Children>

Problem Code - This Doesn't Work, I tried recursively looping, but it doesn't hold the depth/nesting of objects. Please share any pointers.

def RecurseXML(Data_Tree):
    for Children in Data_Tree.iterchildren():
        if Children.tag == "Shape":
            Owner       = Children.getparent().tag
            Owner       = etree.SubElement(Root_Child,Owner)
            SomeValue   = etree.SubElement(Owner,Children.tag,attrib={"Name":Children.attrib['Name']})
            Root_Child.append(SomeValue)
        if len(Children) > 0:
            RecurseXML(Children)

Martin Honnen · Accepted Answer · 2021-07-01 08:02:31Z

1

XSLT is good at that:

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

  <xsl:output method="xml" indent="yes"/>
  <xsl:strip-space elements="*"/>
  
  <xsl:template match="*">
    <xsl:apply-templates/>
  </xsl:template>

  <xsl:template match="Children | Shape | ContainedObjects">
    <xsl:copy>
      <xsl:copy-of select="@*"/>
      <xsl:apply-templates/>
    </xsl:copy>
  </xsl:template>

</xsl:stylesheet>

lxml allows you to run XSLT.

answered Jul 1, 2021 at 8:02

Martin Honnen

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2 Comments

Pratik V Over a year ago

Hey Martin, Could you please point me towards a good source of learning/building XSL Templates? This might resolve a lot of Transformations I need to work on!

Martin Honnen Over a year ago

There are lots of books and courses, cranesoftwrights.github.io/books/ptux/index.htm is available for free, the author also has a video course on Udemy, although there you need to check which parts or hours are for free. stackoverflow.com/tags/xslt/info has a larger list of resources for learning, coding and practising.

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