Author: Marc D. Anderson
http://mdasblog.wordpress.com

I’m going to go back to the XPath Math / Number functions for this article to cover a few of them. Most of these functions are fairly intuitive, but I’m a math guy. (Yup, I even majored in it in college back during the Renaissance.) However, I find that the “documentation” in the XPath Expression Builder is a bit obtuse for these functions so I’m just going to run through some of them “in my own words”. If I state the obvious or repeat the descriptions in the XPath Expression Builder, please forgive me. Your refund is in the mail.

average()

average() computes the average of a set of numbers. You’ll generally use this function in the body template because you need a nodeset (multiple items) for an average to make sense. This is analogous to the way you’ll typically use sum. So, you go into the XPath Expression Builder, and you select average, and you see:

sum() div count()

What the heck? In fact, there is no average function. Tricked you, didn’t we? (SharePoint Designer and I like to pal around on stuff like this.) You need to insert the column you want the average of in both the sum() and the count() functions, like this:

<xsl:value-of select="sum(/dsQueryResponse/Rows/Row/@Potential_x0020_Value) div count(/dsQueryResponse/Rows/Row/@Potential_x0020_Value)"/>

This computes the average just like we all learned in grade school, but you’ve got to do a little more work. Because I’m putting this into the dvt_1.body function, I need to specify the full XPath to the column. Here’s where this fits into the dvt_1.body template to make it useful:

<xsl:template name="dvt_1.body">
  <xsl:param name="Rows"/>
  <xsl:for-each select="$Rows" >
    <xsl:call-template name="dvt_1.rowview"/>
  </xsl:for-each>
  <tr>
    <td>
    </td>
    <td class="ms-vb" align="right" colspan="2">
      <b><xsl:value-of select="format-number(sum(/dsQueryResponse/Rows/Row/@Potential_x0020_Value) div count(/dsQueryResponse/Rows/Row/@Potential_x0020_Value), &quot;$#,##0.00;-$#,##0.00&quot;)"/></b>
    </td>
  </tr>
</xsl:template>

<xsl:template name="dvt_1.rowview">
  <tr>
    <xsl:if test="position() mod 2 = 1">
      <xsl:attribute name="class">ms-alternating</xsl:attribute>
    </xsl:if>
    <td class="ms-vb">
      <xsl:value-of select="@Title"/>
    </td>
    <td class="ms-vb" align="right">
      <xsl:value-of select="format-number(@Potential_x0020_Value, &quot;$#,##0.00;-$#,##0.00&quot;)"/>
    </td>
  </tr>
</xsl:template>

After I’ve called the dvt_1.rowview template “for-each” item, I am writing out another table row which contains the average. Note that I’ve added the format-number function around the individual values and the average so that they look more presentable.

format-number

Here’s the description of format-number() directly from the XPath Expression Builder:

format-number() simply takes a textual representation of a number and formats it using the format-pattern which you provide.

String bean man again!  When you open the XPath Expression Builder you can never quite read the descriptions of the functions very well. The trick is to manually drag the window larger:

Min and Max

These twins are actually members of the good old ddwrt family. You need to provide them with a nodeset, just like sum and count:

<xsl:value-of select="format-number(ddwrt:Max(/dsQueryResponse/Rows/Row/@Potential_x0020_Value), &quot;$#,##0.00;-$#,##0.00&quot;)"/>

Replacing my average calculation with ddwrt:Max:

Operators

The math operators aren’t functions, but they are worth listing out:

· + – the plus sign, which adds two numbers together

· - – the minus sign, which subtracts one number from another

· * – the asterisk, which is used to multiply two numbers together

· div – div, which divides the first number by the second

That last one threw you, didn’t it? You’re probably used to using the slash character (/) for division. However, in XSL and XPath, the slash means something else entirely. The slash is how you sort of “parse” the nodeset, as you can see in my use of the full XPath for Potential Value above: /dsQueryResponse/Rows/Row/@Potential_x0020_Value

These are a few of the quirky Math / Number functions which are available in XPath. I’ll run through the rest of the Math / Number functions in the next article.

Author: Marc D. Anderson
http://mdasblog.wordpress.com

Marc D. Anderson is a Co-Founder and the President of Sympraxis Consulting LLC, based in Newton, MA.  He has over 25 years of experience as a technology consultant and line manager across a wide spectrum of industries and organizational sizes.  Marc has done extensive consulting on knowledge management and collaboration and what makes them actually work in practice.  Marc is a very frequent “answerer” on the MSDN SharePoint – Design and Customization forum.