Composing URL’s in XSLT

Composing a complex URL can be very ugly in XSLT, using a very long formula of concatenations and encodings.
E.g the REST URL for this YQL query:

select * from html where url=”” and
xpath=’//*[contains(concat( ” “, @class, ” ” ), concat( ” “, “MsoNormal”, ” ” ))]’

Is ugly as sin:*’%2F%2F*%5Bcontains(concat(%20%22%20%22%2C%20%40class%2C%20%22%20%22%20)%2C%20concat(%20%22%20%22%2C%20%22MsoNormal%22%2C%20%22%20%22%20))%5D’&diagnostics=true&

Two possible improvements:

Dedicated URL composition template

Create a template that can be called like this:

<xsl:call-template name=”url”>
<xsl:with-param name=”decom”>
<value><xsl:value-of select=”$query”/></value>

I’m not elaborating this template here. It should be quite straightforward, but there may be a more generic and even more elegant solution:

String Replacement Template

Using the replace template that was created in the XML Translation project.

<xsl:call-template name=”replace”>
<xsl:with-param name=”string”>
<xsl:with-param name=”parameters”>
<query><xsl:value-of select=”encode-for-uri($query)”/></query>
<env><xsl:value-of select=”encode-for-uri(‘store://’)”/></env>

This is the replace template:

<xsl:template name=”replace”>
<xsl:param name=”string”/>
<xsl:param name=”parameters”/>
<xsl:when test=”count($parameters/*) &gt; 0″>
<xsl:variable name=”string2″>
<xsl:value-of select=”replace($string,concat(‘\$’,name($parameters/*[1])),normalize-space($parameters/*[1]))”/>
<xsl:call-template name=”replace”>
<xsl:with-param name=”string” select=”$string2″/>
<xsl:with-param name=”parameters”>
<xsl:copy-of select=”$parameters/*[position() &gt; 1]”/>
<xsl:value-of select=”$string”/>


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