Reusing an existing loop expression

Use a LoopReference function to reuse a loop expression previously defined in another element.

<customers>
	<customer>
		<lastName>Harrison</lastName>
		<firstName>Emily</firstName>
		<state>New Jersey</state>
	</customer>
	<customer>
		<lastName>Reagan</lastName>
		<firstName>James</firstName>
		<state>New Jersey</state>
	</customer>
	<customer>
		<lastName>Smith</lastName>
		<firstName>Karen</firstName>
		<state>Texas</state>
	</customer>
</customers>

<root>
	<customers>
		<state/>
		<customer>
			<lastName/>
			<firstName/>
		</customer>
		<customer>
			<lastName/>
			<firstName/>
		</customer>
	</customers>
	<customers>
		<state/>
		<customer>
			<lastName/>
			<firstName/>
		</customer>
		<customer>
			<lastName/>
			<firstName/>
		</customer>
	</customers>
</root>

1. Right-click the output customers element and click Split Loop to create a separate loop for each state value.

   

2. Click the first customers loop in the output structure and drag and drop a FixedLoop function in its Loop tab.
   This is used to indicate that the output should only produce one iteration of this loop.
3. Drag and drop a Constant function on the first output state element, then double-click the function, enter New Jersey in the Value field and click OK.
4. Drag and drop the input customer element on the first output customer element.
   A SimpleLoop function is automatically added.
5. Drag and drop an Equal function on the Filter argument of the SimpleLoop.
6. Drag and drop the input state element on the First Value argument and the first output state on the Second Value.

   

7. Click the customers[2] element and drag and drop a FixedLoop function in its Loop tab.
8. Drag and drop a Constant function on the second output state element and set its value to Texas.
9. Click the second output customer loop and drag and drop a LoopReference function in its Loop tab.
10. Drag and drop the first output customer loop on the Map Element argument.
    This allows you to specify that the loop used in this element should be the same as the one defined in the first customer element. Unlike the LoopCopy function, the LoopReference does not apply the filters or sort keys defined in the referenced loop.
11. Add an Equal function to the Filter argument and set the input state as First Value and the second output state as Second Value.
12. Drag and drop the input customer element on the second output customer to map the child elements.

Results

Your map is configured and should look like this:

You can use the Test Run feature to see the result. In this example, the following output is returned:

<root>
  <customers>
    <state>New Jersey</state>
    <customer>
      <lastName>Harrison</lastName>
      <firstName>Emily</firstName>
    </customer>
    <customer>
      <lastName>Reagan</lastName>
      <firstName>James</firstName>
    </customer>
  </customers>
  <customers>
    <state>Texas</state>
    <customer>
      <lastName>Smith</lastName>
      <firstName>Karen</firstName>
    </customer>
  </customers>
</root>