Bug #4353: Extra namespaces present when serializing XdmValue using Serializer API - Saxon - Saxonica Developer Community

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Bug #4353

closed

Extra namespaces present when serializing XdmValue using Serializer API

Added by Radu Coravu about 5 years ago. Updated almost 5 years ago.

Status:

Closed

Priority:

Low

Assignee:

Michael Kay

Category:

Serialization

Sprint/Milestone:

Start date:

2019-10-21

Due date:

% Done:

Estimated time:

Legacy ID:

Applies to branch:

9.9

Fix Committed on Branch:

9.9

Fixed in Maintenance Release:

9.9.1.6

Platforms:

Description

I have an "net.sf.saxon.s9api.XdmValue" which resulted from an XQuery update operation. I create a serializer "net.sf.saxon.s9api.Processor.newSerializer(Writer)" and then use it to serialize the value:

serializer.serializeXdmValue(rootElement);

Problem is that with Saxon 9.9 I get extra not-necessary namespaces serialized, something like:

  <p:url href="http://www.example.com" xmlns:p="http://www.oxygenxml.com/ns/samples/personal"/>

so I would prefer somehow to have an extra namespace reducer when writing the content.

I looked at the implementation of "net.sf.saxon.s9api.Processor.writeXdmValue(XdmValue, Destination)" which seems to be adding a namespace reducer on the "else" clause so I used the following workaround on my side:

      processor.writeXdmValue(rootElement, new AbstractDestination() {
        
        @Override
        public Receiver getReceiver(PipelineConfiguration pipe, SerializationProperties params)
            throws SaxonApiException {
          return serializer.getReceiver(pipe, params);
        }
        
        @Override
        public void close() throws SaxonApiException {
          serializer.close();
        }
      });

to force the code on the "else" branch and add that extra namespace reducer. But maybe "serializer.serializeXdmValue(rootElement);" could by default somehow use an namespace reducer by default.

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Updated by Radu Coravu about 5 years ago

To refine my XML example, the fully serialized XML fragment using the default Serializer approach looks like this:

<p:personnel xmlns:p="http://www.oxygenxml.com/ns/samples/personal">
  <p:person id="harris.anderson" photo="personal-images/harris.anderson.jpg">
    <extra><p:url href="http://www.example.com" xmlns:p="http://www.oxygenxml.com/ns/samples/personal"/></extra>
  </p:person>
</p:personnel>

so that "p:url" element has an extra xmlns:p="http://www.oxygenxml.com/ns/samples/personal" declaration which is also on the root element.

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Updated by Michael Kay about 5 years ago

It would be interesting to know how the redundant namespace declaration got into the XdmValue in the first place; perhaps the right fix would be to stop that happening.

We've made some efforts to formalize the interface between the "transformation" and "destination" sides of the Receiver interface: see the Javadoc for class RegularSequenceChecker. The rules (in 9.9) don't say they're can't be redundant namespaces. In 10.0 the interface changes so that the startElement() event includes a NamespaceMap object which must include all in-scope namespaces for an element; that puts the onus firmly on the destination side to eliminate duplicates when serializing.

This means that any solution for 9.9 can afford to be a bit pragmatic, and I'm inclined to tackle it by adding a NamespaceReducer to the Receiver returned by QueryResult.serializeSequence(), which underpins Serializer.serailize(XdmValue).

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