[使用dataweave合并数组中的元素

Question

输入：

{
  "letterCountArray": [
    {
      "letter": "A",
      "count": 5
    },
    {
      "letter": "B",
      "count": 3
    },
    {
      "letter": "C",
      "count": 6
    },
    {
      "letter": "D",
      "count": 5
    },
    {
      "letter": "E",
      "count": 6
    }
  ]
}

预期输出：

  {
    "count D+E": 11
  }

我尝试了以下数据编织，但未成功：

%dw 1.0 
%input payload application/json
%output application/json
---
payload.letterCountArray filter ($.letter == "D" or $.letter == "E") map { "countD+E": $ reduce ($ + $) } 

Answer 1

这将汇总元素：

%dw 1.0
%input payload application/json
%output application/json
---
"count D+E": sum (payload.letterCountArray filter ($.letter == "D" or $.letter == "E") map (
    $.count
))