List to Tree doesn't work when key_id and key_parent is string.

The option passed in for empty_children is ignored when GetTree is called. It always calls with false.

See line 54

Sometime, we need an order_key to sort the tree.
Could we add this feature?

Hi, This library works well with my list except that it rearrange some records with negative IDs and puts them at the beginning instead of their normal location.

Is there a way around it ?

License

I recommend add license to the people can use the package in commercial projects too

I am facing some issues while parsing the tree; where in the big tree it does not parse the node appropriately. but When I test with only that specific sub tree it works okay.

I am getting below warnings for all the missing nodes in the tree. This might be helpful for you.
Warning
tree.js:42
RowDataPacket { id: 24834, name: "Loans for vehicle - interest component", category_id: "Loa556", parent_id: 24904, …}
tree.js:42

uMode.find({}, (err,data) => {
let ltt = new LTT(data, {
key_id: 'id',
key_parent: 'parent'
});
let tree = ltt.GetTree();
console.log(tree);
}

I have a need to generate a tree from a collection (array of objects). But my paths are nested - eg:

{
  id: 100,
  field: 'val',
  // ... 
  meta: {
    parent: 'abc-123'
  }
}

I need to either pass dot-notation paths (and use a third party lib, like _ or object-path) or, to avoid dependencies, perhaps consider passing a matching fn to the constructor, which I can use third party libs without affecting deps on this module.

// list-to-tree constructor - add new param to end
 constructor(list, options = {}, matcher) {
    const _list = list.map((item) => item);

    options = Object.assign({}, defaultOptions, options);
    this.options = options;
    const { key_id, key_parent } = options;

    sortBy(_list, key_parent, key_id);
    const tree = new IronTree({ [key_id]: 0 });
    _list.forEach((item, index) => {
      tree.add((parentNode) => {
       // crude example below:
        return matcher ? matcher(item, key_id, parentNode, key_parent) : parentNode.get(key_id) === item[key_parent];
      }, item);
    });

    this.tree = tree;
  }

Then you could pass whatever id-to-id matching fns you need.

// my application code
const objectPath = require('object-path')
matcher = function (item, key_id, parentNode, key_parent) {
  return objectPath.get(parentNode, key_id) === objectPath.get(item, key_parent)
}

Now I can use:

new Tree(list, {
  key_id: 'id',
  key_parent: 'meta.parent'
}, matcher)

Thoughts?

Need rewrite code base.
Use package for build tree - https://github.com/DenQ/iron-tree

It seems, links / references do not work with string values.
Is this on purpose? Are there are some reasons?

`const list = [
{
_id: "EL",
parentId: 0
}, {
_id: 2,
parentId: "EL"
}, {
_id: 3,
parentId: "EL"
}
];

getTree() {
const llt = new LLT(list, {
key_id: '_id',
key_parent: 'parentId'
});
return llt.GetTree();
}`

Lib just gives warnings:

Problem

When the child's ID is smaller than the parent's ID, the child may not be associated properly.
The reason is that there is code that sorts by parent ID, then sorts by ID, and adds to the tree.

example

PR

I think you can solve this problem by sorting the list by the depth of the tree.

Here is a suggestion:
#26

Is there a way of removing duplicate children?