Aggregate mapping and unknown numbers of instances

Aggregate mapping is performed from instance to instance. You cannot map the repeatable elements, only the instances.

There might be times when you want to map from all possible inputs to one or more outputs, either an array copy or an assignment to a scalar (such as a summation). For this, there are additional restrictions. You must create all the instances needed and then map from those instances.

There is a special case where you might not know how many instances will arrive and the order is either unpredictable or irrelevant. The summation example described in Repeating mappings is a common case; in this situation, use the [All] node as the input without using the other numbered instances. Create a mapping to the scalar target as normal and a loop executes from 1 to the cardinality of the number of repeating element runtime instances in the source and performs the same, aggregated operation on the target. The Compose Expression editor shows the loop in addition to the usual fields to provide the required information about the mapping.

Related concepts
Mapping conditions
Case mappings
Related tasks
Developing mappings
Configuring a mapping
Related reference
Mappings