java - 在 DataWeave 中递归遍历和展平 JSON 对象

问题描述

我想遍历并展平具有以下结构的大型 JSON 文件，显示产品层次结构（将其视为在线商店中的导航）：

productGroups: [
    {
        "key": "child 1"
        ...
        "childrenProductGroups": [
            {
                "key": "child 1.1",
                ...,
                "childrenProductGroups": []
            },
            {
                "key": "child 1.2"
                ...
                "childrenProductGroups": [
                    {
                        "key": "child 1.2.1",
                        ...,
                        "childrenProductGroups": [
                            {
                                "key": "child 1.2.1.1",
                                ...,
                                childrenProductGroups": [
                                    ...
                                ]
                            }
                        ]
                    },
                    {
                        "key": "child 1.2.2",
                        ...,
                        "childrenProductGroups": []
                    }
                ]
                
            },
            {
                "key": "child 1.3",
                ...,
                "childrenProductGroups": [
                    ...
                ]
            }
        ]
    }, 
    {
        "key": "child 2",
        ...,
        "childrenProductGroups": [
            ...
        ]
    },
    {
        "key": "child 3",
        ...,
        "childrenProductGroups": [
            ...
        ]
    }
]

我想以这样的格式将它们展平：

{
    "hierarchieSet": [
        {
            "Nodeid": "00000001", # Number in this json
            "Nodename": "child 1",
            "Tlevel": "01", # First child of product group
            "Parentid": "00000000", # Parent is null
            "Childid": "00000002", # Child node number
            "Nextid": "00000008" # Node number on the same level (child 2)
        }, 
        {
            "Nodeid": "00000002",
            "Nodename": "child 1.1",
            "Tlevel": "02",
            "Parentid": "00000001",
            "Childid": "00000003",
            "Nextid": "00000003"
        }, 
        {
            "Nodeid": "00000003",
            "Nodename": "child 1.2",
            "Tlevel": "02",
            "Parentid": "00000002",
            "Childid": "00000005",
            "Nextid": "00000007"
        }, 
        {
            "Nodeid": "00000004",
            "Nodename": "child 1.2.1",
            "Tlevel": "03",
            "Parentid": "00000003",
            "Childid": "0000005",
            "Nextid": "00000006"
        }
        , 
        {
            "Nodeid": "00000005",
            "Nodename": "child 1.2.1.1",
            "Tlevel": "04",
            "Parentid": "00000004",
            "Childid": "0000000", #No more children
            "Nextid": "00000000"
        }, 
        {
            "Nodeid": "00000006",
            "Nodename": "child 1.2.2",
            "Tlevel": "03",
            "Parentid": "00000003",
            "Childid": "0000000",
            "Nextid": "00000000"
        }, 
        {
            "Nodeid": "00000007",
            "Nodename": "child 1.3",
            "Tlevel": "02",
            "Parentid": "00000001",
            "Childid": "0000000",
            "Nextid": "00000000"
        }, 
        {
            "Nodeid": "00000008",
            "Nodename": "child 2",
            "Tlevel": "01",
            "Parentid": "00000000",
            "Childid": "0000009", # 00000009 not shown
            "Nextid": "00000014" # 
        }, 
        ...
        {
            "Nodeid": "000000014",
            "Nodename": "child 3",
            "Tlevel": "01",
            "Parentid": "00000000",
            "Childid": "00000015",
            "Nextid": "00000000" # 00000010 does not exist
        }
    ]
}

因此，我确定了一些主要问题：

树结构的递归
转换元素
扁平化结构
跟踪父母、兄弟姐妹和孩子
跟踪递归级别
格式化数字

我试图通过两种不同的方法来解决这个问题：

使用 DataWeave 转换所有元素
使用Java遍历结构

由于我对函数式编程还很陌生，因此我将更多的精力放在了 Java 实现上，但遇到了许多问题。

Java 方法 读取 json > Init Tree var 并为顶级数组调用中的每个元素分配 Java 实例 > 。树.java：

traverse(data, level)Tree.java

import org.json.JSONObject;

public class Tree {
    private int id = 0;
    private List<Node> nodes = new ArrayList<Node>();
    
    public Tree() {
        nodes.add(new Node("01", "00000001", "HOME", "01", "00000000", "00000002", "00000000"));
    }
    
    public void traverse(String data, int level) {
        System.out.println(data);
        // TODO parse json
    }
    
    private void visit(JSONObject parent, JSONObject node, int level) {
        id++;
        nodes.add(new Node("01", String.valueOf(id), node.getString("key"), String.valueOf(level), "", "", ""));
    }
    
    public List<Node> getNodes() {
        return nodes;
    }

    private static class Node {
        private String zshop, nodename, parentid, childid, nextid, nodeid, tlevel;
        
        public Node(String zshop, String nodeid, String nodename, String tlevel, String parentid, String childid, String nextid) {
            this.zshop = zshop;
            this.nodeid = nodeid;
            this.nodename = nodename;
            this.tlevel = tlevel;
            this.parentid = parentid;
            this.childid = childid;
            this.nextid = nextid;
        }
    }
}

调用调用操作时，我使用此有效负载：

%dw 2.0
output application/java
---
{
    data: vars.rootMessage.payload as String,
    level: 1
}

但这会产生以下错误：

“无法强制对象 { 编码：UTF-8，mediaType：text/json；charset=UTF-8，mimeType：text/json，原始：org.mule.weave.v2.el.SeekableCursorStream@50ecee52 } (org.mule. weave.v2.el.MuleTypedValue@511ba9cc) 到字符串

5| 数据：vars.rootMessage.payload 作为字符串，^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 跟踪：在 main (line : 5, column: 7)" 评估表达式："%dw 2.0 output application/java --- { data: vars.rootMessage.payload as String, level: 1 }"。

我尝试了很多事情：

将其转换为ProductGroup我用 Java 编写的对象
尝试将检索到的对象转换为org.json.JSONObject
尝试缓冲和读取vars.rootMessage.payload (Binary)

但是我无法解决任何这些问题。

DataWeave 方法 我的 .dw 脚本

%dw 2.0
fun append
(item: Object, acc: Object = {
}) = acc ++ item

fun mapper(item: Object) = 
{
    Zshop: "01",
    Nodeid: "00000000",
    Nodename: item.key as Number as String {format: ""},
    Tlevel: "02",
    Parentid: "00000000",
    Childid: "00000000",
    Nextid: "00000000"
}
    
fun traverse(a: Array, level: Number) = 
    a map $ flatMap(value, index) -> value
    
output application/json
---
{
    test: payload.productGroups reduce (item, acc) -> append(mapper(item), acc)
}

我试图解决一些问题的地方。mapper(item)应该创建我可以附加到最终输出的 json 对象appender(item, acc)。递归已经勾勒出来，但还不是我主要关心的问题。

这产生了这个结果：

(original payload),
"Zshop": "01",
"Nodeid": "00000000",
"Nodename": "800",
"Tlevel": "02",
"Parentid": "00000000",
"Childid": "00000000",
"Nextid": "00000000",
"Zshop": "01",
"Nodeid": "00000000",
"Nodename": "110",
"Tlevel": "02",
"Parentid": "00000000",
"Childid": "00000000",
"Nextid": "00000000",
"Zshop": "01",
"Nodeid": "00000000",
"Nodename": "720",
"Tlevel": "02",
"Parentid": "00000000",
"Childid": "00000000",
"Nextid": "00000000",
"Zshop": "01",
"Nodeid": "00000000",
"Nodename": "710",
"Tlevel": "02",
"Parentid": "00000000",
"Childid": "00000000",
"Nextid": "00000000",
...

我想知道为什么我在没有任何对象结构的情况下得到一个平坦的结果。

我的问题：

Java：为什么我不能转换字符串或者它是如何正确完成的
DataWeave：有没有我看不到的简单解决方案？
为什么它是一个平坦的结果而不是一个对象？
reduce和功能的用法是否flatMap正确？

欢迎任何帮助和/或反馈。

标签： javajsontransformationdataweavemulesoft

java - 在 DataWeave 中递归遍历和展平 JSON 对象

问题描述

解决方案

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