I have a question about Params in XSLT. I need to incement a variable (or param) in one of my templates. I can't call the template that I am using recursively becuase is has SVG embedded within it to draw a chart.

Is it possible to call another template and pass a param to be incremented and then pass that param back?

Or can I put another template within the chart template to increment the param.

Or are there any other ways of going about doing this?

Thanks in advance.

Trevor.

You say you need to increment a variable or param, but many such problems can be solved using the position() function which is in effect self-incrementing.

You say:

>I can't call the template that I am using recursively becuase is has SVG embedded within it to draw a chart.

But that looks like a non-sequitur. I can't see any reason why the fact that your template has SVG embedded within it should stop you calling it recursively.

If you can't use position(), you need to use recursion.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

I can't use the position() function because I have a set of customer inestments within my xml document. Each customer has more than one investment but each customer has a unique ID. For each customer I need to loop through all the records that contain the same customer ID and draw a new "bar" in my bar chart for each investment that customer has.

I want to start drawing the bar chart from the left hand side of the screen so if I use the position function the bar chart starts to get rendered off the screen on the right hand side by the time we are on the third customer.

I basically need to reset the "position counter" for each new customer and increment it until there are no more records left for that customer. Then reset the counter and start again for the next customer etc etc...

I can't see how to use recursion in this case as the SVG graphic wont render properly as far as I can see.

Below is my current Bar Chart template with position() being used as the counter.


  <xsl:template name="barChart">
    <fo:instream-foreign-object>
      <svg width="400px" height="560px" xmlns="http://www.w3.org/2000/svg">
        <text x="40" y="25"
            style="font-family:Times New Roman; font-size: 10; fill: #0099ff; stroke: black; stroke-width: 1">
          Position Summary Histogram
        </text>
        <g id="BarChart" transform="translate(0,150) scale(1)" x="0" y="400">

          <xsl:for-each select="$source">
            <xsl:if test="number(PortfolioID) = $currentSecurity -1">
              <xsl:variable name="val" select="Quantity"/>
              <rect x="{position()*25}" y="-{$val div 10}" height="{$val div 10}" width="15" stroke = "wheat" fill = "cornflowerblue"/>
              <text x="{position()*25 + 7.5}" y="0" rotate="50" style="font-family:arial;text-anchor:middle;baseline-shift:-15;$pagePosition = $pagePosition+1">
                  <xsl:value-of select="./SecurityID"/>
              </text>
            </xsl:if>

          </xsl:for-each>
        </g>
      </svg>
  </fo:instream-foreign-object>
    <block break-before="page"/>
  </xsl:template>


Below is an example of my XML

<NewDataSet>
  <Security>
    <PortfolioID>1</PortfolioID>
    <Quantity>183.84</Quantity>
    <FirstName>James</FirstName>
    <LastName>Carter</LastName>
    <Description>Stone Money Market</Description>
    <SecurityID>20</SecurityID>
  </Security>
  <Security>
    <PortfolioID>1</PortfolioID>
    <Quantity>623.08</Quantity>
    <FirstName>James</FirstName>
    <LastName>Carter</LastName>
    <Description>Vantage Bond Index Fund</Description>
    <SecurityID>24</SecurityID>
  </Security>
  <Security>
    <PortfolioID>1</PortfolioID>
    <Quantity>605.358</Quantity>
    <FirstName>James</FirstName>
    <LastName>Carter</LastName>
    <Description>Pimco Total Return Fund</Description>
    <SecurityID>25</SecurityID>
  </Security>
  <Security>
    <PortfolioID>1</PortfolioID>
    <Quantity>454.295</Quantity>
    <FirstName>James</FirstName>
    <LastName>Carter</LastName>
    <Description>Montgomery Equity Income</Description>
    <SecurityID>26</SecurityID>
  </Security>
  <Security>
    <PortfolioID>2</PortfolioID>
    <Quantity>1147.6</Quantity>
    <FirstName>Kathleen</FirstName>
    <LastName>Carter</LastName>
    <Description>Stone Money Market</Description>
    <SecurityID>20</SecurityID>
  </Security>
  <Security>
    <PortfolioID>2</PortfolioID>
    <Quantity>706.667</Quantity>
    <FirstName>Kathleen</FirstName>
    <LastName>Carter</LastName>
    <Description>Pimco Total Return Fund</Description>
    <SecurityID>25</SecurityID>
  </Security>

>I basically need to reset the "position counter" for each new customer and increment it until there are no more records left for that customer. Then reset the counter and start again for the next customer etc etc...

No, that's what you would need to do if you were using a procedural programming language. You can't use the same kind of thinking in a functional programming language: and usually you don't need to. You're instinctively thinking about the problem algorithmically rather than functionally.

You first need to group securities by customer: in XSLT 2.0 use xsl:for-each-group, in 1.0 use Muenchian grouping (www.jenitennison.com/xslt/grouping). Then you need to iterate over the resulting customers. In this grouped iteration position() will give you the current customer number and can be used to compute the x coordinate in your graphic.

Schematically, in XSLT 2.0:

<xsl:for-each-group select="Security" group-by="PortfolioID">
  <xsl:variable name="x" select="position()*0.25"/>
  <xsl:for-each select="current-group()">
     -- draw a rectangle --




Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Unfortunately I dont have XSLT V2.0 so I am trying to use the Muenchian grouping method as you suggested.

Below is my key and template:

  <xsl:key name="portfolios" match="NewDataSet/Security" use="number(.//PortfolioID)"/>

  <xsl:template match="NewDataSet/Security" name="Tester">
    <xsl:for-each select="Security[count(. | key('portfolios', number(.//PortfolioID))[1]) = 1]">
      <xsl:sort select="number(.//PortfolioID)" />
      <xsl:for-each select="key('portfolios', number(.//PortfolioID))">
        <xsl:sort select="forename" />
        <xsl:value-of select="position()"/>
        <xsl:value-of select=".//FirstName" />
        <xsl:value-of select=".//LastName" />
      </xsl:for-each>
    </xsl:for-each>
  </xsl:template>



I am just trying to get this basic template working before I make it more complex. Currently, when I run it nothing happens at all. I want it to group all the records by "PortfolioID" and then display the position and names of all records.

Using this method, will positio() reset itself for each new group that has been created?

<xsl:template match="NewDataSet/Security" name="Tester">
    <xsl:for-each select="Security[...]"

Your Security element does not have any children called Security.

You want

<xsl:template match="NewDataSet">

I think.

<xsl:sort select="forename" />

I don't see an element called forename.



Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Thank you very much, that works great now and I can use the position() function as a counter for each group as well!

It's iteresting to note though that it wont work at all if I call the template by name. But if I call <xsl:apply-templates/> then it works fine. Why might that be?

Thanks again for your excellent help, I appreciate it a great deal.

>It's iteresting to note though that it wont work at all if I call the template by name. But if I call <xsl:apply-templates/> then it works fine.

position() is the position of the current node in the current iteration: apply-templates and for-each establish a current iteration, as do "/" and "[]".


Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference