Re: what's the best way to validate input parameters to a stylesheet?

"Chris Papademetrious [email protected]" <[email protected]> Fri, 19 Mar 2021 22:29:46 -0000
Newsgroups gmane.text.xml.xsl.general.mulberrytech
Message-ID <[email protected]>
Hey, I really like that! Although I think I’ll use $valid-args, then use a “/not($valid-args)” match.

Thank you!!


  *   Chris


From: Wendell Piez [email protected] <[email protected]>
Sent: Friday, March 19, 2021 6:08 PM
To: [email protected]
Subject: Re: [xsl] what's the best way to validate input parameters to a stylesheet?

Hey Chris,

You could pull the logic into a static variable:

<xsl:variable name="doc-fails" as="xs:boolean" select="matches($from.att, '^@\w+=\w+$') and matches($to.att, '^@\w+=\w+$')"/>

then

<xsl:template match="/[$doc-fails]">
  ... this document fails ...
</xsl:template>

Make the @priority explicit if you want to give a better hint.

It's really factoring out the choose into a template match in the normal way. You could even do it without the variable for maximum mystery.

Cheers, Wendell



On Fri, Mar 19, 2021 at 5:58 PM Chris Papademetrious [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> wrote:
Hello! I’ve got a stylesheet that takes two string parameters:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform<https://urldefense.com/v3/__http:/www.w3.org/1999/XSL/Transform__;!!A4F2R9G_pg!MQ0PKGJ8iTMGj8nbezhr8RahBDELg2Lr11DA9cfXfWGlSiD8o6YQvglkeOzZWFJDzoAE_zHtMvO5XdQ$>" version="2.0">

  <xsl:param name="from.att" as="xs:string"/>
  <xsl:param name="to.att"   as="xs:string"/>

Both parameters are expected to be strings in the form of

@attributename=value

At first I tried adding a check at the top level of the stylesheet:

<xsl:if test="not(matches($from.att, '^@\w+=\w+$') and matches($to.att, '^@\w+=\w+$'))">
  <xsl:message terminate="yes">Input parameters must be in the form '@attributename=value'.</xsl:message>
</xsl:if>

but <xsl:if> isn’t allowed at the top level of a stylesheet.

So for now I’m doing this in a “dummy” root element template that doesn’t do anything:

  <!-- this doesn't actually do anything other than validate our input parameters -->
  <xsl:template match="/" priority="20">
    <xsl:choose>
      <xsl:when test="matches($from.att, '^@\w+=\w+$') and matches($to.att, '^@\w+=\w+$')">
        <xsl:next-match/>
      </xsl:when>
      <xsl:otherwise>
        <xsl:message>Input parameters must be in the form '@attributename=value'.</xsl:message>
        <xsl:copy-of select="."/>
      </xsl:otherwise>
   </xsl:choose>
  </xsl:template>

but I feel like there’s probably a better way. Is there?

-----
Chris Papademetrious
Tech Writer, Implementation Group
(610) 628-9718 home office
(570) 460-6078 cell

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