lodash transform object with array to array of objects

Question

Using a lodash, I want to transform an object that contains array into array of objects. here is an example:

Original object :

[
  {
    name:"name1"
    params: [{param: "value1"}, {param: "value2"}]
  },
  {
    name:"name2"
    params: [{param: "value3"}, {param: "value4"}]
  }
]

After transformation:

[
  {name:"name1", param: "value1"},
  {name:"name1", param: "value2"},
  {name:"name2", param: "value3"},
  {name:"name2", param: "value4"}
]

Whats the easiest way to achieve this ? Thanks

[EDIT]

Till now I implemented the function below, but I'm almost sure there must be more elegant solution for my problem.

transform (res) {

            const data = [];

            _.each(res, (obj) => {
                const params = _.pick(obj, ['params']);
                const withoutParams = _.omit(obj, 'params');
                _.each(params.params, (param) => {
                    data.push(_.assign(param, withoutParams));
                });
            });
            console.log('data', data);

            return data

        }

Ori Drori · Accepted Answer · 2016-08-19 11:58:40Z

You can _.map() the params and the name of each object into an array of objects, and then _.flatMap() all objects arrays into one array:

var arr = [
  {
    name:"name1",
    params: [{param: "value1"}, {param: "value2"}]
  },
  {
    name:"name2",
    params: [{param: "value3"}, {param: "value4"}]
  }
];

var newArr = _.flatMap(arr, function(obj) {
  return _.map(obj.params, function(param) {
    return {
      name: obj.name,
      param: param.param
    };
  });
});

console.log(newArr);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.15.0/lodash.min.js"></script>

And this is the ES6 version using Array.prototype.map(), arrow functions, and destructuring:

const arr = [
  {
    name:"name1",
    params: [{param: "value1"}, {param: "value2"}]
  },
  {
    name:"name2",
    params: [{param: "value3"}, {param: "value4"}]
  }
];

const newArr = _.flatMap(arr, ({
  name, params
}) => params.map(({
  param
}) => ({
  name, param
})));

console.log(newArr);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.15.0/lodash.min.js"></script>

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