DataWeave groupBy 和 maxBy

Question

我有点像 DataWeave 新手。我正在尝试获取用户的最新扣除记录，但也按数组中的类型进行分组。这是我必须处理的数据：

"users": [
    {
        "employeeId": "123456",
        "lastName": "smith",
        "firstName": "joe ",
        "deductions": [
            {
                "deductionType": "ABC",
                "Amt": 1000,
                "StartDate": "2001-01-02T00:00:00"
            },
            {
                "deductionType": "ABC",
                "Amt": 1000,
                "StartDate": "2019-01-02T00:00:00"
            },
            {
                "deductionType": "ABC",
                "Amt": 1000,
                "StartDate": "2016-01-02T00:00:00"
            },
            {
                "deductionType": "DCA",
                "Amt": 4000,
                "StartDate": "2019-11-02T00:00:00",
            }
        ]
    }

我尝试使用发布在以下位置的类似解决方案：Dataweave 2.0 maxBy and filter 但这似乎不起作用，因为我得到了一个空有效负载。

最终结果应该是这样的：

    "users": [
    {
        "employeeId": "123456",
        "lastName": "smith",
        "firstName": "joe ",
        "deductions": [
            {
                "deductionType": "ABC",
                "Amt": 1000,
                "StartDate": "2019-01-02T00:00:00"
            },
            {
                "deductionType": "DCA",
                "Amt": 4000,
                "StartDate": "2019-11-02T00:00:00",
            }
        ]

我目前尝试的解决方案是：

    payload.users map {($),
               deductions: (($.deductions groupBy $.deductionType) mapObject (value, key) -> 
                            {(key) : (value maxBy $.benefitStartDate)}) pluck (value) -> value

}

但这也不起作用。

Answer 1

试试这个

{ 
    users: payload.users map {
        ($ - "deductions"),
        deductions: (($.deductions groupBy $.deductionType) pluck $) map {
            ($ maxBy $.StartDate)
        }
    }
}

Answer 2

这是一种不同的解决方案，请使用性能更好的解决方案:)。 算法的注释可以在 DW 表达式中看到。 此外，我在代码中对您的示例数据进行了硬编码，因此您只需复制和粘贴即可确认 DW 表达式有效。

%dw 2.0
output application/dw

var data = "users": [
    {
        "employeeId": "123456",
        "lastName": "smith",
        "firstName": "joe ",
        "deductions": [
            {
                "deductionType": "ABC",
                "Amt": 1000,
                "StartDate": "2001-01-02T00:00:00"
            },
            {
                "deductionType": "ABC",
                "Amt": 1000,
                "StartDate": "2019-01-02T00:00:00"
            },
            {
                "deductionType": "ABC",
                "Amt": 1000,
                "StartDate": "2016-01-02T00:00:00"
            },
            {
                "deductionType": "DCA",
                "Amt": 4000,
                "StartDate": "2019-11-02T00:00:00",
            }
        ]
    }
]
---
users: data.users map do {
    // Sort by StartDate, I type casted to a `DateTime` instead of comparing strings
    // Reverse the sorted list such that the latest dates are at the top of the list
    // Finally, get a set out the list where uniqueness is the deductionType
    //   since distinctBy maintains the first element that matches and removes the rest
    //   you know have a list of distinct deductionType with the latest date.       
    var ds = ($.deductions orderBy ($.StartDate as DateTime))[-1 to 0]
              distinctBy (d) -> d.deductionType
    ---
    {
        ($ - "deductions"),
        deductions: ds
    }
}