Javascript - 将数组转换为递归对象[重复]

Question

我有一个递归对象的结构：

const obj = {
  name: 'entity-0',
  children: [{
    name: 'entity-0-0',
    children: []
  }, {
    name: 'entity-0-1',
    children: [{
      name: 'entity-1-0',
      children: []
    }]
  }]
}

我目前正在将其转换为这样的平面数组：

const arr = [];

function convertObjToArr(obj, level, parent) {
  arr.push({ name: obj.name, parent: parent?.name, level });
  obj.children.forEach(v => this.convertObjToArr(v, level + 1, obj));
}

convertObjToArr(obj, 0);

这导致数组看起来像这样：

[
  { name: 'entity-0', level: 0 },
  { name: 'entity-0-0', parent: 'entity-0', level: 1 },
  { name: 'entity-0-1', parent: 'entity-0', level: 1 },
  { name: 'entity-1-0', parent: 'entity-0-1', level:  2}
]

我现在需要做的是扭转这个过程。我将生成的arr 作为输入并得到obj 作为输出。这可能吗？我该怎么做？

据我所知：

function convertArrToObj(iArr) {
  for(let i = 0; i < iArr.length; i++) {
    if(!iArr[i].parent) newObj = { ...iArr[i], children: [] };
    else {
      // this should somehow find iArr[i].parent and insert itself into its children array
    }
  }
}

但是正如你所看到的，它是不完整的，我很确定它不会是递归的，所以如果它的深度超过 1 层，它将无法工作，我不认为。

Answer 1

这可能有效。

如果只有一个根，则取结果数组中的第一个元素。

const arr = [
  { name: 'entity-0', level: 0 },
  { name: 'entity-0-0', parent: 'entity-0', level: 1 },
  { name: 'entity-0-1', parent: 'entity-0', level: 1 },
  { name: 'entity-1-0', parent: 'entity-0-1', level:  2}
];

const convertArrToObj = (arr, parent) => {
    return arr.filter(item => item.parent === parent)
        .reduce((acc, item) => {
            acc.push({name: item.name, children: convertArrToObj(arr, item.name)});
            return acc;
        }, []);
};

const result = convertArrToObj(arr);

console.log(result);

// using map is simpler, advised by Nick Parsons
const convertArrToObj2 = (arr, parent) => {
    return arr.filter(item => item.parent === parent)
        .map(item => ({name: item.name, children: convertArrToObj2(arr, item.name)}));
};

console.log(convertArrToObj2(arr));

Answer 2

您可以采用一个循环并构建一个新结构。

const
    getTree = (data, root) => {
        const t = {};
        data.forEach(({ name, parent }) => 
            ((t[parent] ??= {}).children ??= []).push(Object.assign(t[name] ??= {}, { name }))
        );
        return t[root].children;
    },
    data = [{ name: "entity-0", parent: undefined, level: 0 }, { name: "entity-0-0", parent: "entity-0", level: 1 }, { name: "entity-0-1", parent: "entity-0", level: 1 }, { name: "entity-1-0", parent: "entity-0-1", level: 2 }],
    tree = getTree(data);

console.log(tree);

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