JS: dot notation to nested object

Question

i struggle with this simple function. My goal is it to parse a dot notated string to a nested object.

An array of this:

["image", "groups", "groups.tasks", "groups.image"]

Should me give this:

[{
        path: "image",
        populate: []
    }, {
        path: "groups",
        populate: [{
                path: "tasks",
                populate: []
            }, {
                path: "image",
                populate: []
            }]
    }]

My code so far:

let populate = [];
const query = ["image", "groups", "groups.tasks", "groups.image"];


function parse(str, arr) {


	let c = str.split(".");
	let p = c.shift();

	console.log(c)

	let entry = {
		path: p,
		populate: []
	};


	if (c.length > 0) {

		console.log("Add to '%s'", p, c)
		parse(c.join("."), entry.populate);

	} else {

		arr.push(entry);

	}


}


query.forEach(function (str, index) {

	parse(str, populate);

});

console.log(populate)

All i get is the parent array, no childs:

[ { path: 'image', populate: [] },
  { path: 'groups', populate: [] } ]

I want to use it in a RESTful API where i can populate over nested mongoose documents. The populate array pass i then to the ".populate(...)" function in my express route

e.g:

GET /api/computer?populate=image,groups,group.tasks

There should be no limitation on the deep of nested objects.

By my reaseaches i found this awnser: How transform string dot notation to nested object? But im not sure how to modify it to reach my goal.

Nina Scholz · Accepted Answer · 2018-09-25 09:32:29Z

3

You could reduce the array by reducing the splitted path strings.

var array = ["image", "groups", "groups.tasks", "groups.image"],
    result = array.reduce((r, s) => {
        s.split('.').reduce((a, path) => {
            var object = a.find(o => o.path === path);
            if (!object) {
                a.push(object = { path, populate: [] });
            }
            return object.populate;
        }, r);
        return r;
    }, []);
    
console.log(result);

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

answered Sep 25, 2018 at 9:32

Nina Scholz

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1 Comment

Marc Over a year ago

Awesome! Thanky you verry much!

Just code · Accepted Answer · 2018-09-25 09:41:23Z

You can do something like this.

var aa = ["groups","image","groups.tasks", "groups.image" ]
var result = [];
aa.forEach(element => {

    if (!result.some(a=> a.path === element) && element.indexOf(".") === -1) {
        result.push({ path: element, populate: [] })
    } else {
        if (element.indexOf(".") !== -1) {
            let splittedText = element.split(".");
            if (result.some(a=> a.path === splittedText[0])) {
               var index= result.findIndex(a=> a.path === splittedText[0]);
               result[index].populate.push({ path: splittedText[1], populate: [] });
            }else{
              result.push({ path: splittedText[0], populate: [{ path: splittedText[1], populate: [] }] })              
            }
            
        }
    }
});
console.log(result);

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