conditional template matching & failure

[this is long, so only read if you're in a helpful mood]

I'm fairly new to XSL (yes, I've checked alternate resources before
posting), so this is probably a no-brainer for experienced XSL
programmers.

Generally, I have an XML file with student schedule information in it and
I want to print each class out when given a specific student & term. A
student may not exist in the XML file, however, for whatever reason.


> if student & term found
   > print schedule
> else
  > give a "not found" msg

---------
Problems:
---------

1. Without using xsl:if or :choose, I can't stop a failed template match
from dumping the entire data

   Example:
	<xsl:template match="//schedule[@username=$thisUser]">
        ...
        </xsl:template>

   Results: prints out entire XML if $thisUser is not found


2. Using xsl:if and :choose doesn't traverse me down the tree to the
elements I want to print, so I'm writing long (and expensive) XPaths on
the subsequent condition

   Example:
	<xsl:for-each
select="//schedule[@username=$thisUser]/semester[season=$thisSeason and
year=$thisYear]/course">
	  ...
	</xsl:for-each>

   Results: long, slow, inefficient XPath - should just be able to say
"for-each select='course'"


3. I can't use a template match with a VariableReference (student name),
but I can't create a separate template for every case either (too many
students)

   Example:
	<xsl:apply-templates
select="//schedule[@username=$thisUser]/semester"/>
	  ...
	<xsl:template match="//schedule[@username=$thisUser]/semester">
	  ...
	</xsl:template>

   Results: invalid XSL

---------------------
schedule.xml
---------------------
<schedules>

  <schedule username="tommy">

    <semester>
      <season>fall</season>
      <year>2002</year>

      <course>
        <title>Calc 1</title>
        <desc>...</desc>
      </course>

      <course>
        <title>Gym</title>
        <desc>...</desc>
      </course>

    </semester>

  </schedule>

</schedules>
--------------------
- can be 1 to many <schedule>
- can be 1 to many <semester>
- can be 1 to many <course>
--------------------

I want to template match to the level of <semester> so I'm only
processing at that level to print out the course info and if the
<schedule> username attribute is not found, it returns "not found."

I tried doing something like:

<xsl:template match="schedule[@username=$thisUser]">

  <table>

  <xs:apply-templates select="semester[season=$thisSeason and
year=$thisYear]"/>

  </table>

</xsl:template>

<xsl:template match="semester[season=$thisSeason and year=$thisYear]">
   <xsl:for-each select="course">

     <tr><td><xsl:value-of select="title"/></td></tr>

   </xsl:for-each>
</xsl:template>

------
This obviously fails because you can't have a VariableReference in the
template match, but this is the gist of what I'm trying to accomplish.

Any and all help is appreciated as I try to get my feet wet.


Regards,
_ryan


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