Form a nested tree from an array of objects in javascript-CodePudding

So there is array of objects of below format

let inputs = [
    {
      "id": "614344d9d9c21c0001e6af2e",
      "groupName": "Unassigned",
      "parentGroup": "null"
    },
    {
      "id": "614447da152f69c3c1d52f2e",
      "groupName": "P1",
      "parentGroup": "null"
    },
    {
      "id": "614447da152f69c3c1d52f38",
      "groupName": "K1",
      "parentGroup": "C1"
    },
    {
      "id": "614447da152f69c3c1d52f3e",
      "groupName": "A2",
      "parentGroup": "C2"
    },
    {
      "id": "614447da152f69c3c1d52f40",
      "groupName": "G1",
      "parentGroup": "P2"
    },
    {
      "id": "614447da152f69c3c1d52f46",
      "groupName": "F1",
      "parentGroup": "null"
    },
    {
      "id": "614447da152f69c3c1d52f30",
      "groupName": "P2",
      "parentGroup": "null"
    },
    {
      "id": "614447da152f69c3c1d52f36",
      "groupName": "C2",
      "parentGroup": "P1"
    },
    
    {
        "id": "614447da152f69c3c1d52f3c",
        "groupName": "A1",
        "parentGroup": "C2"
      },
      {
        "id": "614447da152f69c3c1d52f34",
        "groupName": "C1",
        "parentGroup": "P1"
      },
      {
        "id": "614447da152f69c3c1d52f32",
        "groupName": "P3",
        "parentGroup": "null"
      },
      {
        "id": "614447da152f69c3c1d52f3a",
        "groupName": "K2",
        "parentGroup": "C1"
      },
      {
        "id": "614447da152f69c3c1d52f42",
        "groupName": "GG1",
        "parentGroup": "G1"
      },
      {
        "id": "614447da152f69c3c1d52f44",
        "groupName": "GGG1",
        "parentGroup": "GG1"
      }
  ]

i am trying to create a tree structure of format

{name:'p1',children:[{name:'c1':children:[]}]}

so i sorted all the elements of given array considering element with parentGroup as "null" to be at the top of the array.

 let finalArr = [];
 inputs.sort((a,b)=> (a.parentGroup === "null") ? -1 : 1);

And for each element of the inputs array, i was iterating below logic

inputs.forEach(ele => {
            if(ele.parentGroup === "null"){
             let child= {name:ele.groupName,children:[]};
             finalArr.push(child);
            }else{
              finalArr.forEach(item => {
                this.findNode(item,ele);
              })
            }
          });

If the 'parentGroup' of element is "null", then create a leaf kind of obj and push the element to 'finalArr' array

Else, then iterate across all the elements of 'finalArr' over a recursion function

public findNode(ele, obj){
    if(ele.children.length === 0){
      if(ele.name === obj.parentGroup){
        let child = {name:obj.groupName, children:[]};
      ele.children.push(child);
      }
    }else{
      let j = ele.children.length-1;
      this.findNode(ele.children[j--],obj);
    }
  }

This recursion function will check the element has children or not, if no children, then compare the parentGroup of given obj, with name of element from 'FinalArr'. if so ,push the current obj to the children of the element of finalArr.

else, that is, when children has more elements, the same recursion will be triggered until depth of the element is reached.

With this i tought i would make a tree structure with given inputs array, but when a parent has more children, of same level, this logic fails, so the inputs array has 'c1' which is a child of 'p1', but nly the child 'c2' resides, not sure the what is that i missed.

CodePudding user response：

I think the issue is how finalArr is used to generate the html elements.

When doing console.log(finalArr) it looks like the code block below. So it seems to me like the code you have to build the structure of finalArr is working fine.

// console.log(finalArr)

[
  { "name": "P3", "children": [] },
  {
    "name": "P2",
    "children": [
      {
        "name": "G1",
        "children": [
          { "name": "GG1", "children": [
              { "name": "GGG1", "children": [] }
            ]
          }
        ]
      }
    ]
  },
  { "name": "F1", "children": [] },
  {
    "name": "P1",
    "children": [
      { "name": "C2", "children": [
          { "name": "A1", "children": [] }
        ]
      }
    ]
  },
  { "name": "Unassigned", "children": [] }
]

CodePudding user response：

You could take a standard algorithm for getting a tree with given data

const
    getTree = (data, id, parent, root, fn = o => o) => {
      var t = {};
      data.forEach(o => ((t[o[parent]] ??= {}).children ??= []).push(Object.assign(t[o[id]] = t[o[id]] || {}, fn(o))));
      return t[root].children;
    },
    data = [{ id: "614344d9d9c21c0001e6af2e", groupName: "Unassigned", parentGroup: "null" }, { id: "614447da152f69c3c1d52f2e", groupName: "P1", parentGroup: "null" }, { id: "614447da152f69c3c1d52f38", groupName: "K1", parentGroup: "C1" }, { id: "614447da152f69c3c1d52f3e", groupName: "A2", parentGroup: "C2" }, { id: "614447da152f69c3c1d52f40", groupName: "G1", parentGroup: "P2" }, { id: "614447da152f69c3c1d52f46", groupName: "F1", parentGroup: "null" }, { id: "614447da152f69c3c1d52f30", groupName: "P2", parentGroup: "null" }, { id: "614447da152f69c3c1d52f36", groupName: "C2", parentGroup: "P1" }, { id: "614447da152f69c3c1d52f3c", groupName: "A1", parentGroup: "C2" }, { id: "614447da152f69c3c1d52f34", groupName: "C1", parentGroup: "P1" }, { id: "614447da152f69c3c1d52f32", groupName: "P3", parentGroup: "null" }, { id: "614447da152f69c3c1d52f3a", groupName: "K2", parentGroup: "C1" }, { id: "614447da152f69c3c1d52f42", groupName: "GG1", parentGroup: "G1" }, { id: "614447da152f69c3c1d52f44", groupName: "GGG1", parentGroup: "GG1" }],
    tree = getTree(data, 'groupName', 'parentGroup', null, ({ groupName: name }) => ({ name }));

console.log(tree);

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