Merge different rows of an array using lodash

Question

I have a JSON array which has the following entries:

[{"customer":"xyz","date":"10.10.2014","attr1":"ABC","attr2":"001"},{"customer":"xyz","date":"10.10.2014","attr3":"XYZ","attr4":"123"},{"customer":"xyz","date":"11.10.2014","attr1":"DEF","attr2":"002"},{"customer":"xyz","date":"11.10.2014","attr3":"DDD","attr4":"222"}]

Is there a way, using lodash, I can merge the array so that this becomes:

[{"customer":"xyz","date":"10.10.2014","attr1":"ABC","attr2":"001","attr3":"XYZ","attr4":"123"},{"customer":"xyz","date":"11.10.2014","attr1":"DEF","attr2":"002","attr3":"DDD","attr4":"222"}]

Basically use the "date" attribute to merge multiple rows with different JSON attributes into a single JSON object entry ?

What should happen if the date values are the same but the customer values are different (is that not possible with your data)? — cybersam
– cybersam, Commented Oct 7, 2016 at 0:46

Ori Drori · Accepted Answer · 2016-10-07 14:35:23Z

1

Use _.groupBy() to group the objects by date. Then _.merge() each group:

var customers = [{"customer":"xyz","date":"10.10.2014","attr1":"ABC","attr2":"001"},{"customer":"xyz","date":"10.10.2014","attr3":"XYZ","attr4":"123"},{"customer":"xyz","date":"11.10.2014","attr1":"DEF","attr2":"002"},{"customer":"xyz","date":"11.10.2014","attr3":"DDD","attr4":"222"}];

var result = _(customers)
  .groupBy('date') // group the objects by date
  .map(function(item) { // map each group
    return _.merge.apply(_, item); // merge all objects in the group
  })
  .value();

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.16.4/lodash.js"></script>

edited Oct 7, 2016 at 14:35

answered Oct 7, 2016 at 14:19

Ori Drori

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Meir · Accepted Answer · 2016-10-07 09:54:07Z

0

Here is a solution using lodash 3.10.1. I assumed you want to merge each pair and that the second element of a pair will override existing properties from the first one (if there are such).

var source  = [{"customer":"xyz","date":"10.10.2014","attr1":"ABC","attr2":"001"},{"customer":"xyz","date":"10.10.2014","attr3":"XYZ","attr4":"123"},{"customer":"xyz","date":"11.10.2014","attr1":"DEF","attr2":"002"},{"customer":"xyz","date":"11.10.2014","attr3":"DDD","attr4":"222"}];

var chunked = _.chunk(source, 2);

var result = _.map(chunked, _.spread(_.merge));

console.log(result);

And here is a working jsbin.

answered Oct 7, 2016 at 9:54

Meir

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