如何在XSLT中保留xml元素的空白

Question

When I transform an xml document into another xml document, I want to preserve white spaces.

input XML:

<Item>
    <type>4</typr>
    <name>         test      </name>
</Item>

XSLT:

<?xml version="1.0" encoding="utf-8" ?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="xml" omit-xml-declaration="yes"/>
    <xsl:strip-space elements="*"/>
    <xsl:preserve-space elements="name"/>

    <xsl:template match="Item">
       <xsl:element name="Itemtransformed">
           <xsl:element name="itemname"><xsl:value-of select="//name></xsl:element>
       </xsl:element>
    </xsl:template>
</xsl:stylesheet>

Expected output:

<Itemtransformed>
    <itemname>         test      </itemname>
</Itemtransformed>

When I tried to transform this in .Net using System.Xml.Xsl.XslCompiledTransform.Transform(IXPathNavigable input, XsltArgumentList arguments, XmlWriter results), I get below error

"White space cannot be stripped from input documents that have already been loaded. Provide the input document as an XmlReader instead."

Any idea how to fix it or any other possible way to preserve white space.

Thank you for your valuable time

Answer 1

The issue is nothing to do with the leading and trailing whitespace around "test", which XSLT will preserve automatically whatever you say in xsl:strip-space and xsl:preserve-space . Rather the issue here is a limitation in the Microsoft System.Xml.Xsl implementation of xsl:strip-space - a restriction which is explained (not especially well) in the question cited by @RomanSS.

Basically, if you supply a pre-built DOM tree as input to an XSLT processor, then the requirement in the XSLT spec to strip whitespace text nodes is rather challenging, and it looks as if Microsoft have responded to the challenge by imposing a restriction. Other ways to meet this requirement include:

(a) Modify the supplied DOM tree in-situ to delete the whitespace text nodes

(b) Wrap the supplied DOM tree in a wrapper that makes the whitespace text nodes invisible when navigating the tree

(c) Bulk copy the supplied DOM tree to a new tree in which the whitespace text nodes are omitted.

Saxon uses all three strategies under difference circumstances; all of them are expensive. It's far more efficient to do the whitespace stripping while parsing the document and building the tree, which is what Microsoft are forcing you to do by imposing a restriction.

But none of this has anything to do with your problem. If you get rid of the xsl:strip-space and xsl:preserve-space declarations, the whitespace around "test" will be preserved as you want it to be. The xsl:strip-space and xsl:preserve-space declarations only affect text nodes that consist entirely of whitespace.

Answer 2

Maybe this is what you are looking for. There doesn't seem to exist problem in the code shown. White space cannot be stripped from input documents that have already been loaded. Provide the input document as an XmlReader instead