[xsl] Re: Default attribute value templates

Subject: [xsl] Re: Default attribute value templates
From: Dimitre Novatchev <dnovatchev@xxxxxxxxx>
Date: Wed, 27 Jun 2001 13:28:40 -0700 (PDT)
Trevor Nash wrote:

> Is there a way of specifying via an attribute value template (or
> similar mechanism) that the attribute is absent?
> Example:
> I have a template which matches a specific element, then does an
> apply-templates with a sort.  The application is supposed to be fairly
> generic, so it seems a nice idea to allow those attributes of sort
> which are attribute value templates to be parameterized thus:
> <xsl:template match="x">
>      <xsl:apply-templates>
>            <xsl:sort order="{@order}" ... />
>      </xsl:apply-templates>
> </xsl:template>
> The problem is, given <x>...</x> the transformation fails "order must
> be ascending or descending".
> I can see how I could handle this by substituting appropriate values
> when the attribute is mising, but
>   a) it would involve hard wiring the default values, which would be
> bad news if they ever changed
>   b) it seems inordinately messy
>   c) I don't think it would always behave identically if for example
> the input is  <x order="">...</x> : becuase some processors might take
> this as 'use the default', others will reject it.
> Have I missed anything?

Hi Trevor,

MSXML does not signal an error and interprets the lack of @order or an empty string
value of @order exactly as you wanted -- the whole AVT is discarded and no "order"
attribute is specified.

I wonder if this is not a bug in MSXML 4.

Otherwise, one solution to your problem is the following:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
<xsl:template match="x">
    <xsl:when test="@order and (@order = 'ascending'
                                or @order = 'descending')">
           <xsl:sort order="{@order}"/>


Hope this helped.

Dimitre Novatchev.

Do You Yahoo!?
Get personalized email addresses from Yahoo! Mail

 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list

Current Thread