I think there's a problem with the approach you are using to learning the
language. You're basically guessing, and you're guessing wrong. Where did
you get the idea of using curly braces in ${no_hobbie} = 'false'? Probably
from some previous language you have used in which curly braces are used in
such a context. That's an understandable mistake. But when the compiler then
tells you
 
XPST0003: XPath syntax error at char 1 on line 35 in {${no_hobbies}: 

    expected "<name>", found "{"

 
surely the right thing to do is to look up in your favourite XPath reference
book or tutorial what the correct syntax for a variable reference is? That
can't be hard.
 
On the other hand, writing
 
        <xsl:choose> 

        <xsl:when test="empty($hobbie)">

          <xsl:variable name="no_hobbie" select="true"/>  

        </xsl:when>

        <xsl:otherwise>

          <xsl:variable name="no_hobbie" select="false"/>

        </xsl:otherwise>

      </xsl:choose>

 

is a common mistake made by people transferring from other languages, and
it's understandable that you should be confused by the error message. But if
you did some reading, I'm sure the introductory chapters of any XSLT book
would explain that variables in XSLT aren't like the variables of a
procedural language: you can't assign to them at arbitrary points in your
processing logic.

 

Several of your code examples use instructions like xsl:if outside the
context of a template, or put templates in the middle of an instruction.
This shows that you haven't yet grasped the basic structure of a stylesheet,
which consists of a set of templates and functions each containing
instructions. I don't think that it's going to be helpful to give you more
coding snippets until you have understood the basic concepts, and for that I
really think you would be well advised to do some reading.

 

Michael Kay

http://www.saxonica.com/


  _____  

From: Jack Bush [mailto:netbeansfan@y...] 
Sent: 09 February 2009 10:18
To: xml-dev@l...
Subject: [xml-dev] XSTL stylesheet workarounds for exceptions


Hi All,

 

I am unable to come up with a suitable workaround to kick in when an element
is not available. Below are various approaches attempted without success:

 




Scenario

 


A.

<xsl:template match="/">

  <area>

    <xsl:apply-templates select="//ns:p"/>

      <xsl:variable name="hobbie" select="ns:p[ns:strong='Hobbie:']"/>

      <xsl:apply-templates select="$hobbie"/>

      <xsl:choose>

        <xsl:when test="empty($hobbie)">

          <xsl:variable name="no_hobbie" select="true"/>  

        </xsl:when>

        <xsl:otherwise>

          <xsl:variable name="no_hobbie" select="false"/>

        </xsl:otherwise>

      </xsl:choose>

  </area>

</xsl:template>

 

<xsl:if test="${no_hobbie} = 'false'">

  <xsl:template match="ns:p[ns:strong='Hobbie:']">

    <xsl:for-each select="text()[normalize-space() != '']"> 

      <hobbie><xsl:value-of select="normalize-space()"/></hobbie> 

    </xsl:for-each> 

  </xsl:template> 

</xsl:if>

 


Compilation error

Error at xsl:if on line 35 column 41 

  XPST0003: XPath syntax error at char 1 on line 35 in {${no_hobbies}:

    expected "<name>", found "{"

Error at xsl:if on line 35 column 41 

  XTSE0010: Element xsl:if must not appear directly within xsl:stylesheet

Warning: at xsl:variable on line 13 column 59 

  SXWN9001: A variable with no following sibling instructions has no effect

Warning: at xsl:variable on line 16 column 60 

  SXWN9001: A variable with no following sibling instructions has no effect

Error at xsl:template on line 36 column 53 

  XTSE0010: An xsl:if element must not contain an xsl:template element

Error at xsl:template on line 36 column 53 

  XTSE0010: Element must be used only at top level of stylesheet


B.

<xsl:template match="/">

  <area>

    <xsl:apply-templates select="//ns:p"/>

      <xsl:variable name="hobbie" select="ns:p[ns:strong='Hobbie:']"/>

      <xsl:apply-templates select="$hobbie"/>

      <xsl:choose>

        <xsl:when test="empty($hobbie)">

          <hobbie>Unknown</hobbie>  

        </xsl:when>

        <xsl:otherwise>

          <xsl:template match="ns:p[ns:strong='Hobbie:']"> 

            <xsl:for-each select="text()[normalize-space() != '']"> 

              <hobbie><xsl:value-of select="normalize-space()"/></hobbie> 

            </xsl:for-each> 

          </xsl:template>

        </xsl:otherwise>

      </xsl:choose>

  </area>

</xsl:template>

 


Compilation error

Error at xsl:template on line 17 column 61 

  XTSE0010: An xsl:otherwise element must not contain an xsl:template
element

Error at xsl:template on line 17 column 61 

  XTSE0010: Element must be used only at top level of stylesheet


C.

<xsl:template match="/">

  <area>

    <xsl:apply-templates select="//ns:p"/>

      <xsl:variable name="hobbie" select="ns:p[ns:strong='Hobbie:']"/>

      <xsl:apply-templates select="$hobbie"/>

      <xsl:choose>

        <xsl:when test="empty($hobbie)">

          <hobbie>Unknown</hobbie>  

        </xsl:when>

        <xsl:otherwise>

            <xsl:call-template name="hobbie"/>

        </xsl:otherwise>

      </xsl:choose>

  </area>

</xsl:template>

 

<xsl:template name="hobbie" match="ns:p[ns:strong='Hobbie:']">

  <xsl:for-each select="text()[normalize-space() != '']"> 

    <hobbie><xsl:value-of select="normalize-space()"/></hobbie> 

  </xsl:for-each> 

</xsl:template>

 


Output

<hobbie>fishing</hobbie>      // should pick up the valid element if there
is one exist.

<hobbie>Unknown</hobbie>  // only create a default element value when no
such element exist. 


D.

<xsl:template match="/">

  <area>

    <xsl:apply-templates select="//ns:p"/>

      <xsl:variable name="hobbie" select="ns:p[ns:strong='Hobbie:']"/>

      <xsl:apply-templates select="$hobbie"/>

      <xsl:if test="empty($hobbie)">

          <hobbie>Unknown</hobbie>  

      </xsl:if>

  </area>

</xsl:template>

 

<xsl:template match="ns:p[ns:strong='Hobbie:']">

  <xsl:for-each select="text()[normalize-space() != '']"> 

    <hobbie><xsl:value-of select="normalize-space()"/></hobbie> 

  </xsl:for-each> 

</xsl:template>

 


Output

<hobbie>fishing</hobbie>      // should pick up the valid element if there
is one exist.

<hobbie>Unknown</hobbie>  // only create a default element value when no
such element exist.

 

I am very new XSLT and can do with some helpful suggestion.

 

Many thanks,

Jack

 



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