Hierarchical json from flat with parent ID

Question

http://jsfiddle.net/eYgGK/

I stole this script from a different post:

function convertToHierarchy() {
  var arry = [
    { "Id": "1", "Name": "abc", "Parent": "", "attr": "abc" },
    { "Id": "2", "Name": "abc", "Parent": "1", "attr": "abc" },
    { "Id": "3", "Name": "abc", "Parent": "2", "attr": "abc" },
    { "Id": "4", "Name": "abc", "Parent": "2", "attr": "abc" }
  ];
  var nodeObjects = createStructure(arry);
  for (var i = nodeObjects.length - 1; i >= 0; i--) {
    var currentNode = nodeObjects[i];
    if (currentNode.value.Parent === "") {
      continue;
    }
    var parent = getParent(currentNode, nodeObjects);

    if (parent === null) {
      continue;
    }

    parent.children.push(currentNode);
    nodeObjects.splice(i, 1);
  }
  console.dir(nodeObjects);
  return nodeObjects;
}

function createStructure(nodes) {
  var objects = [];

  for (var i = 0; i < nodes.length; i++) {
    objects.push({
      value: nodes[i],
      children: []
    });
  }

  return objects;

}

function getParent(child, nodes) {
  var parent = null;

  for (var i = 0; i < nodes.length; i++) {
    if (nodes[i].value.Id === child.value.Parent) {
      return nodes[i];
    }
  }

  return parent;
}

This script produces:

[{
    "value": {
        "Id": "1",
        "Name": "abc",
        "Parent": "",
        "attr": "abc"
    },
    "children": [{
        "value": {
            "Id": "2",
            "Name": "abc",
            "Parent": "1",
            "attr": "abc"
        },
        "children": [{
            "value": {
                "Id": "4",
                "Name": "abc",
                "Parent": "2",
                "attr": "abc"
            },
            "children": []
        }, {
            "value": {
                "Id": "3",
                "Name": "abc",
                "Parent": "2",
                "attr": "abc"
            },
            "children": []
        }]
    }]
}]

What I'm looking for is:

[{
    "Id": "1",
    "Name": "abc",
    "Parent": "",
    "attr": "abc",
    "children": [{

        "Id": "2",
        "Name": "abc",
        "Parent": "1",
        "attr": "abc",
        "children": [{

            "Id": "4",
            "Name": "abc",
            "Parent": "2",
            "attr": "abc"
        }, {

            "Id": "3",
            "Name": "abc",
            "Parent": "2",
            "attr": "abc"
           
        }]
    }]
}]

I need to get rid of "value" wrapper primarily, and the empty child node secondarily. I know I can write a clean up script, but that would be less than best practice. Would be great if someone knows how to fix, or suggest a different script!

Thanks

Answer 1

Try something like

var arry = [{ "Id": "1", "Name": "abc", "Parent": "", "attr": "abc" },
               { "Id": "2", "Name": "abc", "Parent": "1", "attr": "abc" },
               { "Id": "3", "Name": "abc", "Parent": "2", "attr": "abc" },
               { "Id": "4", "Name": "abc", "Parent": "2", "attr": "abc" }];

function convert(array){
    var map = {};
    for(var i = 0; i < array.length; i++){
        var obj = array[i];
        obj.items= [];

        map[obj.Id] = obj;

        var parent = obj.Parent || '-';
        if(!map[parent]){
            map[parent] = {
                items: []
            };
        }
        map[parent].items.push(obj);
    }

    return map['-'].items;

}

var r = convert(arry)

Demo: Fiddle

Result

[{
    "Id" : "1",
    "Name" : "abc",
    "Parent" : "",
    "attr" : "abc",
    "children" : [{
                "Id" : "2",
                "Name" : "abc",
                "Parent" : "1",
                "attr" : "abc",
                "children" : [{
                            "Id" : "3",
                            "Name" : "abc",
                            "Parent" : "2",
                            "attr" : "abc",
                            "children" : []
                        }, {
                            "Id" : "4",
                            "Name" : "abc",
                            "Parent" : "2",
                            "attr" : "abc",
                            "children" : []
                        }]
            }]
}]

Answer 2

@Arun P Johny's answer is good, but it has a problem, when the array is not sorted, it will flush sub-trees. I updated it as this.

var arry = [
                { "Id": "5", "Name": "abc", "Parent": "3", "attr": "abc" },
               { "Id": "2", "Name": "abc", "Parent": "1", "attr": "abc" },
               { "Id": "4", "Name": "abc", "Parent": "2", "attr": "abc" },
               { "Id": "3", "Name": "abc", "Parent": "2", "attr": "abc" },
               { "Id": "1", "Name": "abc", "Parent": "", "attr": "abc" }
               ];

function convert(array){
    var map = {}
    for(var i = 0; i < array.length; i++){
        var obj = array[i]
        if(!(obj.Id in map)){
            map[obj.Id] = obj
            map[obj.Id].children = []
        }

        if(typeof map[obj.Id].Name == 'undefined'){
            map[obj.Id].Id = obj.Id
            map[obj.Id].Name = obj.Name
            map[obj.Id].attr = obj.attr
            map[obj.Id].Parent= obj.Parent
        }

        var parent = obj.Parent || '-';
        if(!(parent in map)){
            map[parent] = {}
            map[parent].children = []
        }

        map[parent].children.push(map[obj.Id])
    }
    return map['-']
}
console.log(JSON.stringify(convert(arry)))

The result is as this:

{
  "children": [
    {
      "children": [
        {
          "Id": "2",
          "Name": "abc",
          "Parent": "1",
          "attr": "abc",
          "children": [
            {
              "Id": "4",
              "Name": "abc",
              "Parent": "2",
              "attr": "abc",
              "children": []
            },
            {
              "children": [
                {
                  "Id": "5",
                  "Name": "abc",
                  "Parent": "3",
                  "attr": "abc",
                  "children": []
                }
              ],
              "Id": "3",
              "Name": "abc",
              "attr": "abc",
              "Parent": "2"
            }
          ]
        }
      ],
      "Id": "1",
      "Name": "abc",
      "attr": "abc",
      "Parent": ""
    }
  ]
}