Question

I need to flip the elements of two nodes. Originally the variable were set with the following command:

    <xsl:variable name="matchesLeft" select="$questionObject/descendant::simpleMatchSet[position()=1]/simpleAssociableChoice"/>
    <xsl:variable name="matchesRight" select="$questionObject/descendant::simpleMatchSet[position()=2]/simpleAssociableChoice"/>

I now want to flip the variable with the following code:

    <xsl:variable name="matchesRight">
        <xsl:choose>
            <xsl:when test="$flippedQuestions='true'">
                <xsl:value-of select="$questionObject/descendant::simpleMatchSet[position()=2]/simpleAssociableChoice"/>
            </xsl:when>
            <xsl:otherwise>
                <xsl:value-of select="$questionObject/descendant::simpleMatchSet[position()=1]/simpleAssociableChoice"/>
            </xsl:otherwise>
        </xsl:choose>
    </xsl:variable>

But it only get the value from the first element and not all elements in the node. How can I achive this?

Answer 1

Use:

<xsl:variable name="matchesRight" select=
 "$questionObject/descendant::simpleMatchSet
                                  [1+($flippedQuestions='true')]
                                          /simpleAssociableChoice"/>

Explanation:

In XPath whenever a boolean value $someBVal is passed to a numeric operator such as +, the boolean is converted to a number (either 0 or 1) using number($someBVal).

By definition:

number(false()) = 0

and

number(true()) = 1

Thus

1+($flippedQuestions='true')

evaluates to 1 if the string value of flippedQuestions isn’t the string "true" and the same expression evaluates to 2 if the string value of flippedQuestions is the string "true" .