using lodash .groupBy. how to add your own keys fo

Question

I have this sample data returned from an API.

I'm using Lodash's _.groupBy to convert the data into an object I can use better. The raw data returned is this:

[
    {
        "name": "jim",
        "color": "blue",
        "age": "22"
    },
    {
        "name": "Sam",
        "color": "blue",
        "age": "33"
    },
    {
        "name": "eddie",
        "color": "green",
        "age": "77"
    }
]

I want the _.groupBy function to return an object that looks like this:

[
    {
        color: "blue",
        users: [
            {
                "name": "jim",
                "color": "blue",
                "age": "22"
            },
            {
                "name": "Sam",
                "color": "blue",
                "age": "33"
            }
        ]
    },
    {
        color: "green",
        users: [
            {
                "name": "eddie",
                "color": "green",
                "age": "77"
            }
        ]
    }
]

Currently I'm using

_.groupBy(a, function(b) { return b.color})

which is returning this.

{blue: [{..}], green: [{...}]}

the groupings are correct, but I'd really like to add the keys I want (color, users). is this possible using _.groupBy? or some other LoDash utility?

Answer 1

You can do it like this

var result = _.chain(data)
    .groupBy("color")
    .pairs()
    .map(function(currentItem) {
        return _.object(_.zip(["color", "users"], currentItem));
    })
    .value();
console.log(result);

Online Demo

Note: Lodash 4.0 onwards, the .pairs function has been renamed to _.toPairs()

Answer 2

Here is an updated version using lodash 4 and ES6

const result = _.chain(data)
    .groupBy("color")
    .toPairs()
    .map(pair => _.zipObject(['color', 'users'], pair))
    .value();

Answer 3

In 2017 do so

_.chain(data)
  .groupBy("color")
  .toPairs()
  .map(item => _.zipObject(["color", "users"], item))
  .value();