Generating and configuring an AgConcat expression

Talend Data Mapper can automatically generate an AgConcat expression to deal with incompatible loops.

<root>
	<loopA>
		<A>a1</A>
		<loopB>
			<B>b11</B>
		</loopB>
		<loopB>
			<B>b12</B>
		</loopB>
		<loopC>
			<C>c11</C>
		</loopC>
		<loopC>
			<C>c12</C>
		</loopC>
	</loopA>
	<loopA>
		<A>a2</A>
		<loopB>
			<B>b21</B>
		</loopB>
		<loopB>
			<B>b22</B>
		</loopB>
		<loopC>
			<C>c21</C>
		</loopC>
		<loopC>
			<C>c22</C>
		</loopC>
	</loopA>
</root>

root
	row (0:*)
		A
		B
		C1
		C2

1. Create a map and add your input and output structure.

   Example

   
2. Drag the input A element to the output A element.
   A looping expression is automatically created on the output row element.

   
3. Drag the input B element to the output B element.
   This action creates a conflict, the looping context of the input B element is not compatible with the current output looping context.
4. Select Generate AgConcat value expression on out$/root/row/B and click OK.
   
   An AgConcat function is automatically added to the output B element.
5. Drag the input C element to the output C1 element, then select Generate AgConcat value expression on out$/root/row/C1 and click OK.
6. Drop a SingleIndex function on the Filter argument of the AgConcat function.
   This allows you to specify that the output C1 element should only return the first value of the input C element.
7. Drag the input C element to the output C2 element, then select Generate AgConcat value expression on out$/root/row/C2 and click OK
   Because the sibling C1 element contains a filter, a matching filter is automatically added to C2 so that it only returns the second value of the input C element.

   

<root>
  <row>
    <A>a1</A>
    <B>b11b12</B>
    <C1>c11</C1>
    <C2>c12</C2>
  </row>
  <row>
    <A>a2</A>
    <B>b21b22</B>
    <C1>c21</C1>
    <C2>c22</C2>
  </row>
</root>