Test within for-each

yankleber · January 5th, 2015, 03:15 PM

Hi,

I use XSLT for a lot of time, but mostly of time I use it wrongly because I am basically a programmer and then I have this habit of think proceduraly.

Anyway, recently I learn this nice way of make tests within a for-each loop:

Code:

<xsl:variable name="AlphaExact">
  <xsl:for-each select="//root/Inventory/InventoryRow[control = 1][1]">
      <xsl:value-of select="substring(InventoryNumber,10,1)" />
  </xsl:for-each>
</xsl:variable>

In this case, it sets my variable 'AlphaExact' with a proper vaue when the 'control' field in a row matches the value 1.

OK, It works fine for me but I really don't know exactly what the [1] does.

Is this the number of times that my test should match then if I replace it with [2] it should have at least two rows matching 1 before to load the var 'AlphaExact' with the given value?

samjudson · January 5th, 2015, 04:41 PM

The [1] is a filter, or predicate in XSLT language, just like the [control = 1] part (which filters the set so that only elements with a sub-element called control having a value equal to 1 are returned).

When a number appears on its own in a predicate then it is equivalent to writing [position() = X], where X is the number.

So [1] returns the first element in the set preceding it, whereas [2] would return the second one. Both would only return 1 element.

You XSLT could be rewritten as this, as you are only selecting 1 element:

Code:

<xsl:variable name="AlphaExact">
   <xsl:value-of select="substring(//root/Inventory/InventoryRow[control=1][1]/InventoryNumber,10,1)" />
</xsl:variable>

yankleber · January 5th, 2015, 06:36 PM

Hey Samjudson, thank you for replying!

I don't want to abuse, but... could you point me a good place for learning XSLT language within this nice and clean non-procedural approach? I think I am tired to struggle with it due to my wrong way of looking at Xpath.

Thank you!

:)

samjudson · January 5th, 2015, 06:37 PM

Well, Wrox have a book....

yankleber · January 5th, 2015, 06:55 PM

Cool, thanks, I didn't have noticed! I will take a look!

:)