如何从json字符串递归地获取父ids

Question

{
  "id": "1",
  "name": "root",
  "children": [
    {
      "id": "1.1",
      "name": "Child 1",
      "children": [
        {
          "id": "1.1.1",
          "name": "Child 1-1",
          "children": [
            {
              "id": "1-1-1",
              "name": "Child 1-1-1",
              "children": [

              ]
            }
          ]
        },
        {
          "id": "1.1.2",
          "name": "Child 1-2",
          "children": [

          ]
        },
        {
          "id": "1.1.3",
          "name": "Child 1-3",
          "children": [

          ]
        }
      ]
    },
    {
      "id": "1.2",
      "name": "Child 2",
      "children": [
        {
          "id": "1.2.1",
          "name": "Child 2-2",
          "children": [

          ]
        }
      ]
    }
  ]
}

这是作为响应的JSON字符串。必须递归地获取父元素的所有父id。

例如，输入为1.2.1，然后返回1.2，输入为1.1.3，然后返回1.1，1

我怎样才能做到这一点？

Answer 1

您可以采用迭代和递归方法，并且

如果给定的数据不是对象，则返回

• chcek，然后返回id的
• 检查，如果找到，则返回一个空数组，该数组由调用的
• children填充，查找后有一个短路，然后再次调用该函数。

​

function getParentIds(object, id) {
    var ids;
    if (!object || typeof object !== 'object') return;          // no object
    if (object.id === id) return [];                            // id found
    return object.children.some(o => ids = getParentIds(o, id)) // call recursive function
        ? [...ids, object.id]                                   // if found, take ids
        : undefined;                                            // otherwise return falsy
}

var data = { id: "1", name: "root", children: [{ id: "1.1", name: "Child 1", children: [{ id: "1.1.1", name: "Child 1-1", children: [{ id: "1-1-1", name: "Child 1-1-1", children: [] }] }, { id: "1.1.2", name: "Child 1-2", children: [] }, { id: "1.1.3", name: "Child 1-3", children: [] }] }, { id: "1.2", name: "Child 2", children: [{ id: "1.2.1", name: "Child 2-2", children: [] }] }] };

console.log(getParentIds(data, '1.2.1')); // ['1.2']
console.log(getParentIds(data, '1.1.3')); // ['1.1', '1']
console.log(getParentIds(data, 'foo'));   // undefined

.as-console-wrapper { max-height: 100% !important; top: 0; }

​

Answer 2

使用dfs的简单递归

​

const data = JSON.parse('{"id":"1","name":"root","children":[{"id":"1.1","name":"Child 1","children":[{"id":"1.1.1","name":"Child 1-1","children":[{"id":"1-1-1","name":"Child 1-1-1","children":[]}]},{"id":"1.1.2","name":"Child 1-2","children":[]},{"id":"1.1.3","name":"Child 1-3","children":[]}]},{"id":"1.2","name":"Child 2","children":[{"id":"1.2.1","name":"Child 2-2","children":[]}]}]}')

function dfs (target, node) {
  if (node.id === target) { return node.id }
  if (!node.children) { return false } // we could even skip that line since in your data you seem to have an empty array
  const has = node.children.find(c => dfs(target, c))
  return has && [node.id].concat(has.id)
}
console.log(dfs('1.2.1', data))
console.log(dfs('1.1.3', data))

​

Answer 3

您必须解析完整的对象，以便递归地在子对象中注入父in。像这样的东西就行了。

function injectParents(data, parents) {
    if(!parents) {
        parents = [];
    }
    parents.push(data.id);
    data.children.map(child=>{
        child.parents = parents;
        if(child.children && child.children.length>0) {
            child = injectParents(child, Array.from(parents));
        }
        return child;
        });
    return data;    
}

你通常会把它叫做

const injectedResponse = injectParents(response, null);