Working With Iterators

An Iterator is a special type of step that allows you to loop (iterate) through an array or list of XML nodes. For each array element or XML node (each "iteration"), you can execute multiple filter rules or transformer steps (the "children").

For example, let us say you are mapping inbound HL7 v2.x messages to an outbound HL7 v2.x template, and you want to copy OBR.16 .1 (ordering provider) component to a the PV1.9.1 (consulting doctor) component in the outbound template.

Typically you would do this with a Message Builder Transformer Step:

This works so far when there is only one OBR segment and one OBR.16 field. But what if you want to handle multiple segments or repeating fields? This is where Iterators come into play.