如何用MuleSoft DataWeave聚合JSON数组并转换为XML？

需求说明 #

需要将给定的JSON订单数组按客户聚合，把同一客户的多个订单合并到对应的客户节点下，最终转换为指定结构的XML。

输入JSON（原输入中Francis的对象缺少逗号，已修正） #

[
    {
        "name": "Alex",
        "city": "Rome",
        "id": "1054",
        "orderId": "100054",
        "amount": "3"
    },
    {
        "name": "Jack",
        "city": "Paris",
        "id": "1078",
        "orderId": "107709",
        "amount": "65"
    },
    {
        "name": "Alex",
        "city": "Rome",
        "id": "1054",
        "orderId": "100987",
        "amount": "34"
    },
    {
        "name": "Francis",
        "city": "LosAngeles",
        "id": "1942",
        "orderId": "100454",
        "amount": "19"
    },
    {
        "name": "Robert",
        "city": "London",
        "id": "1685",
        "orderId": "306954",
        "amount": "98"
    }
]

目标XML结构 #

<?xml version="1.0" encoding="UTF-8"?>
<DeliveryMessage>
    <customer>
        <name>Alex</name>
        <city>Rome</city>
        <id>1054</id>
        <order>
            <orderId>100054</orderId>
            <amount>3</amount>
        </order>
        <order>
            <orderId>100987</orderId>
            <amount>34</amount>
        </order>
    </customer>
    <customer>
        <name>Jack</name>
        <city>Paris</city>
        <id>1078</id>
        <order>
            <orderId>107709</orderId>
            <amount>65</amount>
        </order>
    </customer>
    <!-- 其他客户节点省略 -->
</DeliveryMessage>

DataWeave映射代码 #

%dw 2.0
output application/xml writeDeclaration=true
---
DeliveryMessage: {
    // 按客户ID分组订单
    (payload groupBy $.id) pluck ((orders, customerId) -> 
        customer: {
            // 提取客户基础信息（同组客户信息一致，取第一个即可）
            name: orders[0].name,
            city: orders[0].city,
            id: customerId,
            // 将同组订单映射为order节点数组
            (orders map (order) -> 
                order: {
                    orderId: order.orderId,
                    amount: order.amount
                }
            )
        }
    )
}

关键逻辑说明 #

• groupBy $.id：以客户ID为键，将输入的订单数组分组，得到键为ID、值为对应订单数组的对象
• pluck：把分组后的键值对转换为数组，方便后续生成<customer>节点列表
• orders[0].name/city：同一分组下的订单属于同一个客户，直接取第一个订单中的客户信息即可
• orders map ...：遍历每个分组的订单数组，将每个订单转换为目标XML的<order>节点
• output application/xml writeDeclaration=true：指定输出格式为XML，并自动生成XML声明头

内容的提问来源于stack exchange，提问作者Claudio