Example – using a variable to access lookup data

In this example the data template contains a lookup table that is not included in the source data. The XPath function tdt:template is used to access the lookup table (see tdt:template() for more information about this function).

Data source

<data> <message> <issue id="123" status="i"/> <issue id="789" status="f"/> <issue id="007" status="c"/> </message> </data>

Expected resut

<data> <issues> <issue id="123">In Progress</issue> <issue id="789">Resolved</issue> <issue id="007">Closed</issue> </issues> </data>

Data template

<data> <stmap> <status value="i">In Progress</status> <status value="f">Resolved</status> <status value="c">Closed</status> </stmap> <issues> <issue id="?"/> </issues> </data>

To make this work you must create a rule for the node /data/issues/issue in the template, and use a repeater in this rule to reference /data/message/issue in the source data.

Now that you have referenced the <issue> element in the source data you have access to its attributes, and can create a transformation variable $status for the @status attribute.

The value of the <issue> element in the output should be retrieved from the lookup table, and the $status variable determines which node to retrieve the value from. This is the value of the <status> element that has a @value attribute that equals the value of $status. To achieve this you can use the following XPath:

tdt:template()/data/stmap/status[@value=$status]

The following example summarizes what is described above.

Node:
	/data/message/issue
$status	@status
Attributes and value:
text()	tdt:template()/data/stmap/status[@value=$status]

If you had not used a transformation variable, the result would not be the expected: tdt:template()/data/stmap/status[@value=@status]

This XPath selects <status> elements having equal @value and @status values.