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How to populate an XML tree with an XmlWriter (LINQ to XML)

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One way to populate an XML tree is to use CreateWriter to create an XmlWriter, and then write to the XmlWriter. The XML tree is populated with all nodes that are written to the XmlWriter.

You'd typically use this method when you use LINQ to XML with another class that expects to write to an XmlWriter, such as XslCompiledTransform.

Example: Create an XmlWriter to accept the output of an XSLT transformation

You can use CreateWriter to create an XmlWriter to accept the output of an XSLT transformation. This is shown in the following example, which does the following:

  • Creates an XML tree and an XmlReader to read from it.
  • Creates a new tree and an XmlWriter to write to it.
  • Invokes the XSLT transformation, providing it with the XmlReader and the XmlWriter.

The transformation then populates the new tree.

string xslMarkup = @"<?xml version='1.0'?>
<xsl:stylesheet xmlns:xsl='http://www.w3.org/1999/XSL/Transform' version='1.0'>
    <xsl:template match='/Parent'>
        <Root>
            <C1>
            <xsl:value-of select='Child1'/>
            </C1>
            <C2>
            <xsl:value-of select='Child2'/>
            </C2>
        </Root>
    </xsl:template>
</xsl:stylesheet>";

XDocument xmlTree = new XDocument(
    new XElement("Parent",
        new XElement("Child1", "Child1 data"),
        new XElement("Child2", "Child2 data")
    )
);

XDocument newTree = new XDocument();
using (XmlWriter writer = newTree.CreateWriter())
{
    // Load the style sheet.
    XslCompiledTransform xslt = new XslCompiledTransform();
    xslt.Load(XmlReader.Create(new StringReader(xslMarkup)));

    // Execute the transformation and output the results to a writer.
    xslt.Transform(xmlTree.CreateReader(), writer);
}

Console.WriteLine(newTree);

Dim xslMarkup As XDocument = _
    <?xml version='1.0'?>
    <xsl:stylesheet xmlns:xsl='http://www.w3.org/1999/XSL/Transform' version='1.0'>
        <xsl:template match='/Parent'>
            <Root>
                <C1>
                    <xsl:value-of select='Child1'/>
                </C1>
                <C2>
                    <xsl:value-of select='Child2'/>
                </C2>
            </Root>
        </xsl:template>
    </xsl:stylesheet>

Dim xmlTree As XDocument = _
    <?xml version='1.0'?>
    <Parent>
        <Child1>Child1 data</Child1>
        <Child2>Child2 data</Child2>
    </Parent>

Dim newTree As XDocument = New XDocument()
Using writer As XmlWriter = newTree.CreateWriter()
    ' Load the style sheet.
    Dim xslt As XslCompiledTransform = New XslCompiledTransform()
    xslt.Load(xslMarkup.CreateReader())

    ' Execute the transformation and output the results to a writer.
    xslt.Transform(xmlTree.CreateReader(), writer)
End Using

Console.WriteLine(newTree)

This example produces the following output:

<Root>
  <C1>Child1 data</C1>
  <C2>Child2 data</C2>
</Root>

See also