XSLT, 2nd Edition

Using if Instead of <xsl:choose>

Although the XSLT elements <xsl:if>, <xsl:choose>, <xsl:when>, and <xsl:otherwise> provide the same function as the if-then-else functions of most programming languages, they’re much more verbose. We can use the XPath 2.0 and XQuery 1.0 if operator to simplify things.

Our XSLT 1.0 stylesheet uses <xsl:choose> in two places: to choose the background color of table rows, and to change the decimal format for currency amounts in the first row of each purchase order. Here’s the first <xsl:choose>:

<tr>
  <xsl:attribute name="style">
    <xsl:text>background: </xsl:text>
    <xsl:choose>
      <xsl:when test="position() mod 2">
        <xsl:text>#CCCCFF</xsl:text>
      </xsl:when>
      <xsl:otherwise>
        <xsl:text>#66FF66</xsl:text>
      </xsl:otherwise>
    </xsl:choose>
    <xsl:text>;</xsl:text>
  </xsl:attribute>

We create an attribute named style. If this is an odd-numbered row (position() mod 2 is 1, which evaluates to true), we set the background color to #CCCCFF; otherwise, we set it to #66FF66. In our XSLT 2.0 stylesheet, we can replace those elements with this attribute value template:

<tr style="{if (position() mod 2) 
           then 'background: #CCCCFF;' 
           else 'background: #66FF66;'}">

The other place we use <xsl:choose> is to choose a decimal format. Here’s how we do it in XSLT 2.0:

<xsl:value-of 
  select="if (position() = 1) 
          then format-number(price * qty, '$#,###.00')
          else format-number(price * qty, '#,###.00')"/>

In both cases, we’ve replaced several elements with a single if statement inside an attribute. ...