position() and last() inside nested for-each xslt - xslt

Question

I have a stylesheet I'm using with a perl module that only works with XSLT 1.0. I want to create a JSON array inside a JSON dictionary so I need proper comma seperation for the elements. I'm parsing an XHTML table where there are 1 or more spans in the second cell. So for-each select="./tr" and then for-each select="./td[1]/span" or something like that.
After changing it a little it behaves as expected as Ian said it would.
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text" version="1.0" doctype-system="http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd" doctype-public="-//W3C//DTD HTML 4.01//EN" encoding="UTF-8" />
<xsl:template match="text()">
</xsl:template>
<xsl:template match="table/tbody">
<xsl:text>[</xsl:text>
<xsl:for-each select="./tr[not(#class='no-results')]">
<xsl:text>{"</xsl:text>
<xsl:value-of select="normalize-space(.//strong)" />
<xsl:text>":{"ingredients":{</xsl:text>
<xsl:for-each select=".//div[#class='reagent-list']//a[#class='item-link reagent']">
<xsl:value-of select="substring(./#href, 14)" />:<xsl:value-of select="normalize-space(./span[1])" />
<xsl:if test="position() != last()">
<xsl:text>,</xsl:text>
</xsl:if>
</xsl:for-each>
<xsl:text>}</xsl:text>
<xsl:if test="position() != last()">
<xsl:text>,</xsl:text>
</xsl:if>
<xsl:text>
</xsl:text>
</xsl:for-each>
<xsl:text>]</xsl:text>
</xsl:template>
</xsl:stylesheet>
I realize that the stylesheet does not match the xml below. The actual document is huge. I hope you understand what I mean, though. I just made this up:
<table>
<thead>
<tr>
<th>a</th>
<th>b</th>
<th>c</th>
</tr>
</thead>
<tbody>
<tr>
<td>foo</td>
<td><span>an element</span></td>
<td>bar</td>
</tr>
<tr>
<td>foo</td>
<td><span>an element</span><span>an element</span></td>
<td>bar</td>
</tr>
<tr>
<td>foo</td>
<td><span>an element</span><span>an element</span><span>an element</span><span>an element</span></td>
<td>bar</td>
</tr>
</tbody>
</table>
=>
{
"Row one":["an element"],
"Row two":["an element", "an element"],
"Row three":["an element", "an element", "an element", "an element"]
}
Instead I get this:
{
"Row one":["an element",],
"Row two":["an element", "an element",],
"Row three":["an element" "an element" "an element" "an element"]
}
I've been using position() and last() in a test tag to print a comma and it seems to work correctly for the outer loop, but how do I tell my test tag to use the inner for-each scope when printing the commas that seperate the array?

Answer 1

As mentioned by #IanRoberts, it is difficult to give targeted assistance without seeing what your existing XSLT looks like.
That said, here is a solution that is push-oriented (i.e., no <xsl:for-each>) and does not require last().
When this XSLT:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:my="my"
exclude-result-prefixes="my"
version="1.0">
<xsl:output omit-xml-declaration="no" indent="yes" method="text" />
<xsl:strip-space elements="*" />
<my:ones>
<num>one</num>
<num>two</num>
<num>three</num>
<num>four</num>
<num>five</num>
<num>six</num>
<num>seven</num>
<num>eight</num>
<num>nine</num>
</my:ones>
<xsl:template match="/*">
<xsl:text>{
</xsl:text>
<xsl:apply-templates select="tbody/tr" />
<xsl:text>
}</xsl:text>
</xsl:template>
<xsl:template match="tr">
<xsl:variable name="vPos" select="position()" />
<xsl:if test="$vPos > 1">,
</xsl:if>
<xsl:text> "Row </xsl:text>
<xsl:value-of select="document('')/*/my:ones/*[$vPos]" />
<xsl:text>":[</xsl:text>
<xsl:apply-templates select="td[2]/span" />
<xsl:text>]</xsl:text>
</xsl:template>
<xsl:template match="span">
<xsl:if test="position() > 1">, </xsl:if>
<xsl:value-of select="concat('"', ., '"')" />
</xsl:template>
</xsl:stylesheet>
...is run against the provided XML:
<table>
<thead>
<tr>
<th>a</th>
<th>b</th>
<th>c</th>
</tr>
</thead>
<tbody>
<tr>
<td>foo</td>
<td>
<span>an element</span></td>
<td>bar</td>
</tr>
<tr>
<td>foo</td>
<td>
<span>an element</span><span>an element</span></td>
<td>bar</td>
</tr>
<tr>
<td>foo</td>
<td>
<span>an element</span><span>an element</span><span>an element</span><span>an element</span></td>
<td>bar</td>
</tr>
</tbody>
</table>
...the wanted result is produced:
{
"Row one":["an element"],
"Row two":["an element", "an element"],
"Row three":["an element", "an element", "an element", "an element"]
}
Explanation:
The first template matches the root element. It's purpose is to apply templates to that element's <tr> grandchildren and sandwich those results between { and } (adding newlines as appropriate).
The second template matches <tr> elements. It outputs row information and is instructed to apply templates to all <span> children of the second <td> element (again, sandwiching the results between braces and other text as necessary).
NOTE: instead of using last(), you'll see that the first element outputs a comma, followed by a newline, if the position of this <tr> in the current context is greater than 1. This has the same effect of applying commas correctly; it's merely a different way of looking at the same problem (and is what I use because it seems more efficient to me ;) ).
NOTE: to make this solution more extensible, you'll see that I'm not statically outputting the words "one", "two", etc. in each row. Instead, at the top of the XSLT, I've defined a <my:ones> element to hold onto the text values of each "ones" number. When processing each <tr>, I use the position of that <tr> in the current context to retrieve the correct <num> element's value. I've left it as an exercise to the reader, but it would indeed be possible to define <my:tens>, <my:hundreds>, etc. to scale this solution up to potentially large numbers of rows.
The final template matches <span> elements. Again, it uses an <xsl:if> element to test whether the position of this <span> in the current context is greater than 1; if so, a comma (followed by a space) is output. After that, we merely concatenate two " symbols with the value of the span sandwiched in-between.