op.arrayAggregate( aggColName as String, columndef as String, [options as String] ) as aggregatedef
This function constructs an array whose items are the result of evaluating the column for each row in the group or row set. The result is used for building the parameters used by the prototype.groupBy function.
const op = require('/MarkLogic/optic'); op.fromView('main', 'expenses') .groupBy('Category', op.arrayAggregate("Expense Array", "Amount")) .orderBy('Category') .result();