XML deserialization: error tt:skip and namespaces

[UweFetzer_se38]

To ignore some of the incoming XML elements I'm using the <tt:skip> pattern. This works fine like in the following example:

1. Example: don't skip any elements

Transformation template

<?sap.transform simple?>
<tt:transform xmlns:tt="http://www.sap.com/transformation-templates">
  <tt:root name="ROOT"/>
  <tt:template>
    <data>
      <X1>
        <tt:value ref=".ROOT.COL_A "/>
      </X1>
      <X2>
        <tt:value ref=".ROOT.COL_B "/>
      </X2>
      <X3>
        <tt:value ref=".ROOT.COL_C"/>
      </X3>
    </data>
  </tt:template>
</tt:transform>

Report

    DATA(xml) = |<?xml version="1.0" encoding="UTF-8" standalone="yes"?>\n| &
                |<data>\n| &
                |    <X1>aaa</X1>\n| &
                |    <X2>bbb</X2>\n| &
                |    <X3>ccc</X3>\n| &
                |</data>\n|.

    DATA: BEGIN OF result,
            col_a TYPE string,
            col_b TYPE string,
            col_c TYPE string,
          END OF result.

    TRY.
        CALL TRANSFORMATION ztmp_fuw
          SOURCE XML xml
          RESULT root = result.

        cl_demo_output=>display( result ).

      CATCH cx_st_match_text
            cx_st_match_element
            cx_sy_conversion_data_loss
            INTO DATA(lcx).

        cl_demo_output=>display( lcx->get_text( ) ).
    ENDTRY.

Result

COL_A COL_B COL_C 
aaa   bbb   ccc 

2. Example: skip element X2

Transformation template

<?sap.transform simple?>
<tt:transform xmlns:tt="http://www.sap.com/transformation-templates">
  <tt:root name="ROOT"/>
  <tt:template>
    <data>
      <X1>
        <tt:value ref=".ROOT.COL_A "/>
      </X1>
      <tt:skip name="X2"/>
      <X3>
        <tt:value ref=".ROOT.COL_C"/>
      </X3>
    </data>
  </tt:template>
</tt:transform>

No changes in report.

Result

COL_A COL_B COL_C 
aaa         ccc 

No surprises so far, everything works as expected.

Now we have to process a standarized XML with a namespace in it and the transformation (the skip) doesn't work anymore.

Changed transformation template:

<?sap.transform simple?>
<tt:transform xmlns:tt="http://www.sap.com/transformation-templates">
  <tt:root name="ROOT"/>
  <tt:template>
    <data xmlns="urn:mynamespace">
      <X1>
        <tt:value ref=".ROOT.COL_A "/>
      </X1>
      <tt:skip name="X2"/>
      <X3>
        <tt:value ref=".ROOT.COL_C"/>
      </X3>
    </data>
  </tt:template>
</tt:transform>

Changed XML in the report:

    DATA(xml) = |<?xml version="1.0" encoding="UTF-8" standalone="yes"?>\n| &
                |<data xmlns="urn:mynamespace">\n| &
                |    <X1>aaa</X1>\n| &
                |    <X2>bbb</X2>\n| &
                |    <X3>ccc</X3>\n| &
                |</data>\n|.

Result:

Exception

Element '{urn:mynamespace}X3' expected 

I've tested this behaviour in 7.50 and 7.52, same result.

What am I doing wrong here? Or is it a kernel bug?

Any idea how to use the skip pattern with custom xml namespaces? Or are there any patterns I could use to ignore specific elements - deserialization should work whether they are present or not.

Thank you in advance for your ideas.

Cheers, Uwe

[Sandra_Rossi]

I guess that the skip doesn't work because of missing namespace in name="X2".

You must indicate a namespace prefix before X2 e.g. name="aaaaaaa:X2" with aaaaaaa being any text and xmlns:aaaaaaa="same URI as default namespace" defined in the same node or a node above.

(I don't know how to directly indicate to use the default namespace without using a dummy prefix)

The below code solves your issue:

<?sap.transform simple?>
<tt:transform xmlns:tt="http://www.sap.com/transformation-templates">
  <tt:root name="ROOT"/>
  <tt:template>
    <data xmlns="urn:mynamespace" xmlns:aaaaaaa="urn:mynamespace">
      <X1>
        <tt:value ref=".ROOT.COL_A "/>
      </X1>
      <tt:skip name="aaaaaaa:X2"/>
      <X3>
        <tt:value ref=".ROOT.COL_C"/>
      </X3>
    </data>
  </tt:template>
</tt:transform>

[Sandra_Rossi]

To make all elements optional, you may use tt:extensible="on" or "deep-static" or "deep-dynamic":

<?sap.transform simple?>
<tt:transform xmlns:tt="http://www.sap.com/transformation-templates">
  <tt:root name="ROOT"/>
  <tt:template>
    <data tt:extensible="deep-dynamic" xmlns="urn:mynamespace">
      <X1>
        <tt:value ref=".ROOT.COL_A "/>
      </X1>
      <X3>
        <tt:value ref=".ROOT.COL_C"/>
      </X3>
    </data>
  </tt:template>
</tt:transform>

[UweFetzer_se38]

Great, that's it.

Thank you Sandra!

(still think that "skip" should work with default namespaces and that this is a kernel bug)