XML fix namespace declaration

Question

I am trying to detetct/work around this bug in RSS elements. That means I have to find a wrong namespace-declaration and change its value to the correct namespace. E.g:

xmlns:media="http://search.yahoo.com/mrss"

must be:

xmlns:media="http://search.yahoo.com/mrss/"

How can I achive that given a org.w3c.Document?

I meanwile found out how to get all elements of a certain namespace:

        XPathFactory xpf = XPathFactory.newInstance();
        XPath xpath = xpf.newXPath();
        XPathExpression expr = xpath.compile("//*[namespace-uri()='http://search.yahoo.com/mrss']");


        Object result = expr.evaluate(d, XPathConstants.NODESET);
        if (result != null) {
            NodeList nodes = (NodeList) result;
            for(int node=0;node<nodes.getLength();node++)
            {
                Node n = nodes.item(node);
                this.log.warn("Found old mediaRSS namespace declaration: "+n.getTextContent());
            }

        }

So now I have to figure out how to change the namespace of a Node via JAXP.

Chris Lercher · Accepted Answer · 2010-03-14 22:06:59Z

1

You could probably do it with XSLT, with a rule like this:

<xsl:template match="media:*">
   <xsl:element name="local-name()" namespace="http://search.yahoo.com/mrss/">
      <xsl:apply-templates match="node()|@*"/>
   </xsl:element>
</xsl:template>

where media is bound to "http://search.yahoo.com/mrss".

You may have to tweak the syntax a little, as I'm writing this without the help of a compiler. Also, what you'll get is probably not extremely nicely formatted (namespace declarations on many elements), but it should be locically correct.

answered Mar 14, 2010 at 22:06

Chris Lercher

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10 Comments

er4z0r Over a year ago

Thanks for you reply. However I am accessing the document on the object level. I am also not sure whether the local prefix will always be "media:". After all this are RSS-Feeds made by other people. God knows what prefix they use :-/

Chris Lercher Over a year ago

They don't have to! You can use any prefix in the XSLT (e.g. "x:*"), all that matters is the namespace. (In other words, the prefix you use in XSLT doesn't have anything to do with the prefix in the XML file.)

Mads Hansen Over a year ago

@er4z0r - the namespace prefix that you declare in your XSLT (i.e. media) does not have to match the namespace prefix in the source document. As long as they both refer to the same URI, the template will match.

er4z0r Over a year ago

Just to see, if I got you right. Your XSLT would look for all elements that are prefixed with the prefix representing the "wrong" namespace" and then set the namespace of these directly to the correct namespace?

Chris Lercher Over a year ago

Yes, that's right. You could also try to match "xmlns" attributes, and change them (to get a nicer XML, if you care). But you'll have to change the elements anyway in addition to that.

|

Community · Accepted Answer · 2017-05-23 10:32:33Z

Just for the sake of completeness:

Java Code:

Document d = out.outputW3CDom(converted);
            DOMSource oldDocument = new DOMSource(d);
            DOMResult newDocument = new DOMResult();
            TransformerFactory tf = TransformerFactory.newInstance();
            StreamSource xsltsource = new StreamSource(
                    getStream(MEDIA_RSS_TRANSFORM_XSL));
            Transformer transformer = tf.newTransformer(xsltsource);
            transformer.transform(oldDocument, newDocument);

private InputStream getStream(String fileName) {
    InputStream xslStream = Thread.currentThread().getContextClassLoader()
                .getResourceAsStream("/" + fileName);
    if (xslStream == null) {
        xslStream = Thread.currentThread().getContextClassLoader()      .getResourceAsStream(fileName);
        }
        return xslStream;
    }

Stylesheet:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <!--identity transform that will copy matched node/attribute to the output and apply templates for it's children and attached attributes-->
    <xsl:template match="node()|@*">
        <xsl:copy>
            <xsl:apply-templates select="@*|*|text()" />
        </xsl:copy>
    </xsl:template>

    <!--Specialized template to match on elements with the incorrect namespace and generate a new element-->
    <xsl:template match="//*[namespace-uri()='http://search.yahoo.com/mrss']">
        <xsl:element name="{local-name()}" namespace="http://search.yahoo.com/mrss/" >
            <xsl:apply-templates select="@*|*|text()" />
        </xsl:element>
    </xsl:template>
</xsl:stylesheet>

Special thanks to Mads Hansen for his help with the XSLT.

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