Xpath - Using the logic within the count function

Question

I am trying to use a true or fale statement within the count function of XPath and am encountering a few errors. Here is my code so far:

  <xsl:for-each select="all/courses/allcourses/course">

   <xsl:for-each select="student">

   <xsl:variable name="StudentTotalPoints" select="sum(results/u_points)" />
    <xsl:value-of select="$StudentTotalPoints" />
    <xsl:variable name="amountEnrolled" select="count((360 - $StudentTotalPoints) != 0)" />
        <xsl:value-of select="$amountEnrolled" />

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

the XML code in question is:

   <all>
<courses>
    <allcourses>
    <course> 
        <c_code>U65</c_code>
        <c_title>Computer Science</c_title>
        <coursecp>360</coursecp>
        <student>
        <studentID>10265654</studentID>
        <fname>Sarah</fname>
        <lname>Clarke</lname>
        <results>
             <u_title>Communicating in an IT Environment</u_title>
                        <u_code>CSG1132</u_code>
                        <u_points>15</u_points>
                        <result>65</result>
                        <grade>CR</grade>
        </results>
<results>
             <u_title>Programming Principles</u_title>
                        <u_code>CSP1150</u_code>
                        <u_points>15</u_points>
                        <result>45</result>
                        <grade>N</grade>
        </results>
            </student>

<student> *same structure*  </student>

the problem is on the line where the variable amountEnrolled is declared, when trying to load the page in question I am welcomed with this error:

"Error during XSLT transformation: An XPath expression was expected to return a NodeSet."

So clearly the count function isn't returning anything. What is the best way to go about this? I feel like it should be simple but it definitely isn't. My required result is to count the amount of times that 360 - $StudentTotalPoints does NOT equal to 0, how should I go about this?

Thanks in advance!

Answer 1

a student will have multiple <results> </results> within <student></student>

Okay, then if we take the following example input:

<all>
    <courses>
        <allcourses>
            <course> 
                <c_code>U65</c_code>
                <student>
                    <studentID>1</studentID>
                    <results>
                        <u_points>10</u_points>
                    </results>
                    <results>
                        <u_points>20</u_points>
                    </results>
                    <results>
                        <u_points>30</u_points>
                    </results>
                </student>
                <student>
                    <studentID>2</studentID>
                    <results>
                        <u_points>40</u_points>
                    </results>
                    <results>
                        <u_points>50</u_points>
                    </results>
                    <results>
                        <u_points>360</u_points>
                    </results>
                </student>
            </course>   
        </allcourses>
    </courses>
</all>

and apply this stylesheet:

<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>

<xsl:template match="/">
    <root>
        <xsl:for-each select="all/courses/allcourses/course">
            <course code="{c_code}">
                <xsl:for-each select="student">
                    <student id="{studentID}">
                    <totalPoints><xsl:value-of select="sum(results/u_points)" /></totalPoints>
                    <amountEnrolled><xsl:value-of select="count(results/u_points[.!=360])" /></amountEnrolled>
                </student>
                </xsl:for-each>
            </course>
        </xsl:for-each>
    </root>
</xsl:template>

</xsl:stylesheet>

we will receive:

<?xml version="1.0" encoding="UTF-8"?>
<root>
   <course code="U65">
      <student id="1">
         <totalPoints>60</totalPoints>
         <amountEnrolled>3</amountEnrolled>
      </student>
      <student id="2">
         <totalPoints>450</totalPoints>
         <amountEnrolled>2</amountEnrolled>
      </student>
   </course>
</root>

This is probably not what you want, but it does what you say it should do.

---

Edit:

Sorry, I forgot to specify, how many times within <course>

Okay, then we need to move the count to the parent Course element:

<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>

<xsl:template match="/">
    <root>
        <xsl:for-each select="all/courses/allcourses/course">
            <course code="{c_code}">
                <xsl:for-each select="student">
                    <student id="{studentID}">
                        <totalPoints><xsl:value-of select="sum(results/u_points)" /></totalPoints>
                    </student>
                </xsl:for-each>
                <amountEnrolled>
                    <xsl:value-of select="count(student[sum(results/u_points)!=360])"/>
                </amountEnrolled>
            </course>
        </xsl:for-each>
    </root>
</xsl:template>

</xsl:stylesheet>

If we now modify our input to:

<all>
    <courses>
        <allcourses>
            <course> 
                <c_code>U65</c_code>
                <student>
                    <studentID>1</studentID>
                    <results>
                        <u_points>10</u_points>
                    </results>
                    <results>
                        <u_points>20</u_points>
                    </results>
                    <results>
                        <u_points>30</u_points>
                    </results>
                </student>
                <student>
                    <studentID>2</studentID>
                    <results>
                        <u_points>40</u_points>
                    </results>
                    <results>
                        <u_points>50</u_points>
                    </results>
                    <results>
                        <u_points>270</u_points>
                    </results>
                </student>
            </course>   
        </allcourses>
    </courses>
</all>

we will receive:

<?xml version="1.0" encoding="UTF-8"?>
<root>
  <course code="U65">
    <student id="1">
      <totalPoints>60</totalPoints>
    </student>
    <student id="2">
      <totalPoints>360</totalPoints>
    </student>
    <amountEnrolled>1</amountEnrolled>
  </course>
</root>