How can I replace xmlns namespace attributes with prefixes?

Question

I have been trying to write a utility in C# which takes an XML file, removes the xmlns attributes from the tags, sets the prefix of these attributes in the root tag, and then uses these prefixes in the tags instead.

Source XML file:

<?xml version="1.0" encoding="utf-8"?>
<Main version="1.0" xmlns="urn:root:v1">
    <Report>
        <Title>Some Value</Title>
    </Report>
    <Content>
        <Address>
            <CountryName xmlns="urn:location:v2">Australia</CountryName>
        </Address>
    </Content>
</Main>

Target XML file:

<?xml version="1.0" encoding="utf-8"?>
<root:Main version="1.0" xmlns:root="urn:root:v1" xmlns:loc="urn:location:v2">
    <root:Report>
        <root:Title>Some Value</root:Title>
    </root:Report>
    <root:Content>
        <root:Address>
            <loc:CountryName>Australia</loc:CountryName>
        </root:Address>
    </root:Content>
</root:Main>

I've managed to get part of the way there with the following code. I have replaced all tags with no attributes with the root prefix, and added the xmlns attribute to the root tag, but have not been successful with removing the xmlns attribute from CountryName tag and using the prefix there instead.

XDocument doc = XDocument.Load(@"C:\Temp\Source.xml");

var content = XElement.Parse(doc.ToString());

content.Attributes("xmlns").Remove();

content.Add(new XAttribute(XNamespace.Xmlns + "root", "urn:root:v1"));
content.Add(new XAttribute(XNamespace.Xmlns + "loc", "urn:location:v2"));

foreach (var node in doc.Root.Descendants().Where(n => n.Name.NamespaceName == "urn:location:v2"))
{
    node.Attribute("xmlns").Remove();
    node.Add(new XAttribute(XNamespace.Xmlns + "loc", "urn:location:v2"));
}   

content.Save(@"C:\Temp\Target.xml");

Any help would be appreciated - thanks!

You try to remove attribute from doc's descendants nodes, but save the content to file that you didn't change. So you only need to change `doc.Root.Descendants()` to `content.Descendants()` — George Alexandria, Jul 21 '17 at 20:48
@GeorgeAlexandria Thanks - that's almost done it! I still want to get rid of the `xmlns:loc="urn:location:v2"`. Any ideas? `Australia` — Acewave, Jul 21 '17 at 21:20

Parfait · Answer 1 · 2017-07-22T01:32:40.197

Consider XSLT, the special-purpose language designed to transform XML files. While I personally do not know or use C#, I do know it can run XSLT 1.0 scripts. See answers here. Also, the XSLT processor you choose to use must allow the document() function for this solution.

XSLT (save as .xsl file; notice namespaces declared in header)

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                              xmlns:root="urn:root:v1" xmlns:local="urn:location:v2">
    <xsl:output omit-xml-declaration="no" indent="yes"/>
    <xsl:strip-space elements="*"/>

    <xsl:template match="node()|@*">
       <xsl:copy>
         <xsl:apply-templates select="node()|@*"/>
       </xsl:copy>
    </xsl:template>

    <xsl:template match="*">
      <xsl:element name="root:{name()}" namespace="urn:root:v1">
         <xsl:copy-of select="document('')/*/namespace::local"/>
         <xsl:apply-templates select="node()|@*"/>
      </xsl:element>
    </xsl:template>    

    <xsl:template match="*[local-name()='CountryName']">
      <xsl:element name="local:{name()}" namespace="urn:location:v2">
         <xsl:apply-templates select="node()|@*"/>
      </xsl:element>
    </xsl:template>

</xsl:stylesheet>

C# (see link above)

var myXslTrans = new XslCompiledTransform(); 

myXslTrans.Load("XSLTScript.xsl"); 
myXslTrans.Transform("Input.xml", "Output.xml");

XML Output

<?xml version="1.0"?>
<root:Main xmlns:root="urn:root:v1" xmlns:local="urn:location:v2" version="1.0">
  <root:Report>
    <root:Title>Some Value</root:Title>
  </root:Report>
  <root:Content>
    <root:Address>
      <local:CountryName>Australia</local:CountryName>
    </root:Address>
  </root:Content>
</root:Main>

score 1 · Accepted Answer · answered Jul 22 '17 at 09:26

1

You're not a million miles away. All you need to do is remove any existing namespace declaration attributes and then add the ones you want to the root. The rest will be taken care of.

var doc = XDocument.Load(@"C:\Temp\Source.xml");

doc.Descendants().Attributes().Where(x => x.IsNamespaceDeclaration).Remove();
doc.Root.Add(new XAttribute(XNamespace.Xmlns + "root", "urn:root:v1"));
doc.Root.Add(new XAttribute(XNamespace.Xmlns + "loc", "urn:location:v2"));

doc.Save(@"C:\Temp\Target.xml");

See this fiddle for a demo.

answered Jul 22 '17 at 09:26

Charles Mager

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It is interesting how the second namespace worked. How does it know `` should use the `loc` namespace prefix as you removed all prior? My XSLT explicitly targeted *CountryName* node. +1 anyways! – Parfait Jul 24 '17 at 14:39
1

@Parfait even though the *declarations* were removed, the model still knows the *namespace* of `CountryName`. [When writing](http://referencesource.microsoft.com/#System.Xml.Linq/System/Xml/Linq/XLinq.cs,da605610f51d6a49), it calls [`GetPrefixOfNamespace`](https://msdn.microsoft.com/en-us/library/system.xml.linq.xelement.getprefixofnamespace(v=vs.110).aspx) internally to look through the prefixes in scope and will use that prefix if found. – Charles Mager Jul 24 '17 at 14:47

How can I replace xmlns namespace attributes with prefixes?

2 Answers2