XSLT: testing whether a certain type of non-null element exists... somewhere

Question

I have XML that looks like

<answers>
   <answer>
      <question-number>1</question-number>
      <value>3</value>
      <mean xsi:nil="1" />
    </answer>
   <answer>
      <question-number>2</question-number>
      <value>2</value>
      <mean>2.3</mean>
    </answer>
   <answer>
      <question-number>3</question-number>
      <value>3</value>
      <mean xsi:nil="1" />
    </answer>
....
</answers>

I'm formatting each answer using xsl:for-each. If there is a mean present I have a graphical representation of the mean. For some potential lists of answers the mean will always be null.

At the bottom of the page I want to put a legend explaining the graphical representation of the mean. But I only want it to appear if I actually displayed a mean at all. So I want to be able to do a check, after closing the xsl:for-each, to say "do any of the answer elements have a non-null mean value?".

Really not sure how to do that.

Answer 1

Something like this should work. if you have any means it will return true

<xs:if test="/answers/answer/mean">You have a mean</xs:if>

I think this is what you mean.

Edit: maybe this?

<xs:if test="(count(/answers/answer/mean)==1)">You have a mean<xs:if>

Not sure if this works, but it might

<xs:if test="/answers/answer/mean != nil">You have a mean</xs:if>

Answer 2

do any of the answer elements have a non-null mean value? based on roberts example

<xs:if test="(count(/answers/answer/mean[not(@xsi:nil)])>0"><xs:if>

EDIT:

<xs:if test="//answer/mean[not(text())]"><xs:if>

LAST EDIT (before going home...)

<xs:if test="//answer/mean[attribute::xsi:nil]"><xs:if>

Answer 3

What about something like this?

  <xsl:for-each select="/answers/answer">
      <xsl:if test="mean &gt;= 0">
          ... other code ...
      </xsl:if>
  </xsl:for-each>

Answer 4

<xs:if test="count(/answers/answer/mean[@xsi:nil != '1']) > 0">Mean stuff here</xs:if>

Should do what you want (count the means where the xsi:nil attribute isn't set to 1)

Answer 5

Here's what finally worked for me:

<xsl:if test="//answers/answer/mean>0">

That is to say, "do there exist any answer elements for which the mean value is greater than zero". Fortunately I know that the mean value, if there is one, will in fact always be greater than zero -- unfortunately this isn't a generalized solution for this reason.

I still think the approach that jasper and workmad3 were taking (checking for the xsi:nil attribute) ought to work, but I couldn't get the syntax to actually... work.

Many thanks, all.