Filtering xsl:value-of on attributes

Kawahee · December 16th, 2009, 01:26 AM

Hi,

I currently have an XML document like this:

Code:

<?xml version="1.0" encoding="ISO-8859-1"?>
<?xml-stylesheet type="text/xsl" href="./transform.xsl"?>
<Documentation><Tables>
<TABLE TABLE_NAME="FirstTable">
  <COLUMN COLUMN_NAME="FirstColumn" ORDINAL_POSITION="1" IS_NULLABLE="NO" DATA_TYPE="int" />
  <COLUMN COLUMN_NAME="SecondColumn" ORDINAL_POSITION="2" IS_NULLABLE="NO" DATA_TYPE="int" />
</TABLE>

...

</Tables><Comments>
<COMMENT ForTable="FirstTable" ForColumn="FirstColumn">Description of FirstColumn</COMMENT>
</Comments></Documentation>

My question is, how do I get the value of the COMMENT when looping over the tables and columns? I have:

Code:

<xsl:for-each select="//TABLE">
  ...
  <xsl:for-each select="COLUMN">
    ...
    <xsl:value-of select="//COMMENT[@ForTable = @TABLE_NAME and @ForColumn=@COLUMN_NAME]" />

But this doesn't work. Any advice?

samjudson · December 16th, 2009, 05:00 AM

The thing you have to remember if context. When you are filtering a COMMENT element in a predicate (the square brackets) you are within the context of that COMMENT element, so @ForTable is a valid attribute, but @TABLE_NAME does not exist on a COMMENT element.

You can refer to the XSLT function current() which returns the current context node from outside of the predicate (in this example that would be the COLUMN element).

Code:

<xsl:value-of select="//COMMENT[@ForTable = current()/../@TABLE_NAME AND @ForColumn=current()/@COLUMN_NAME]"/>

It may be easier to read/follow if you create temporary variables however:

Code:

<xsl:for-each select="TABLE">
  <xsl:variable name="tableName" select="@TABLE_NAME"/>
  <xsl:for-each select="COLUMN">
     <xsl:variable name="columnName" select="@COLUMN"/>
     <xsl:value-of select="//COMMENT[@ForTable=$tableName AND @ForColumn=$columnName]"/>
  ...

Kawahee · December 16th, 2009, 07:33 PM

Quote:

Originally Posted by samjudson

Code:

<xsl:value-of select="//COMMENT[@ForTable = current()/../@TABLE_NAME AND @ForColumn=current()/@COLUMN_NAME]"/>

Thank you. This is the solution I ended up using.