How to add one array object to another 2 dimensional array by key with lodash

Question

I have one array of messages for example:

[{
    day: "1",
    msgs: [{day: "1", id: 1, msg: 'txt'}]
},{
    day: "2",
    msgs: [{day: "2", id: 2, msg: 'txt'}]
}]

and I receive new messages from server in this format:

[
    {day: "1", id: 3, msg: 'txt'},
    {day: "1", id: 4, msg: 'txt'},
    {day: "2", id: 5, msg: 'txt'},
    {day: "3", id: 6, msg: 'txt'}
]

And I need to merge new values into old messages array. And this is the example of results I need.

[{
    day: "1",
    msgs: [{day: "1", id: 1, msg: 'txt'},
       {day: "1", id: 3, msg: 'txt'},
       {day: "1", id: 4, msg: 'txt'}]
},{
    day: "2",
    msgs: [{day: "2", id: 2, msg: 'txt'},
       {day: "2", id: 5, msg: 'txt'}]
},{
    day: "3",
    msgs: [{day: "3", id: 6, msg: 'txt'}]
}]

I spend 5h on stack overflow to find similar case but I did not found it. I've already tried using lodash functions groupBy and forEch and it did not work. The important thing is if NEW DAY comes from server to add that day in old results.

Can you show us what you have actually tried and tell us what issue(s) you had with each attempt? — Justin Wood
– Justin Wood, Commented Sep 3, 2016 at 12:31

Redu · Accepted Answer · 2016-09-03 12:50:36Z

1

You requested data format has a lot of redundant information. With due respect i would like to advise you to adjust your code to use a data format as follows;

var data = [{day: "1", id: 3, msg: 'txt'},
            {day: "1", id: 4, msg: 'txt'},
            {day: "2", id: 5, msg: 'txt'},
            {day: "3", id: 6, msg: 'txt'}
           ],
dailyMsg = data.reduce((dm,obj) => dm[obj.day] !== void 0 ? (dm[obj.day] = dm[obj.day].concat({id: obj.id, msg: obj.msg}),dm)
                                                          : (dm[obj.day] = [{id: obj.id, msg: obj.msg}],dm),{});
console.log(dailyMsg);

answered Sep 3, 2016 at 12:50

Redu

26.3k6 gold badges61 silver badges84 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Nenad Vracar · Accepted Answer · 2016-09-03 12:44:14Z

0

You can do this in pure js with forEach() and find()

var ar1 = [{
    day: "1",
    msgs: [{day: "1", id: 1, msg: 'txt'}]
},{
    day: "2",
    msgs: [{day: "2", id: 2, msg: 'txt'}]
}];

var ar2 = [
    {day: "1", id: 3, msg: 'txt'},
    {day: "1", id: 4, msg: 'txt'},
    {day: "2", id: 5, msg: 'txt'},
    {day: "3", id: 6, msg: 'txt'}
];

ar2.forEach(function(o) {
  var e = ar1.find((a) => a.day == o.day);
  (e != undefined) ? e.msgs.push(o) : ar1.push({day: o.day,msgs: [o]});
})

console.log(ar1)

edited Sep 3, 2016 at 12:44

answered Sep 3, 2016 at 12:37

Nenad Vracar

122k16 gold badges160 silver badges184 bronze badges

Comments

kernal_lora · Accepted Answer · 2016-09-03 12:33:49Z

0

Just follow below steps. Array .concat method will concat the two arrays.

    var arry1= [{
        day: "1",
        msgs: [{day: "1", id: 1, msg: 'txt'}]
    },{
        day: "2",
        msgs: [{day: "2", id: 2, msg: 'txt'}]
    }];

      var array2= [
        {day: "1", id: 3, msg: 'txt'},
        {day: "1", id: 4, msg: 'txt'},
        {day: "2", id: 5, msg: 'txt'},
        {day: "3", id: 6, msg: 'txt'}
    ];

var fullArray= arry1.cancat(array2);

answered Sep 3, 2016 at 12:33

kernal_lora

1,1553 gold badges13 silver badges26 bronze badges

Comments

robcaa · Accepted Answer · 2016-09-03 12:54:55Z

It think Nenad Vracar solution is the best. If the ECMAScript 6 is supported.

My solution does not require: ECMAScript 6

var oldMessages = [
    {
        day: "1",
        msgs: [{day: "1", id: 1, msg: 'txt'}]
    },
    {
        day: "2",
        msgs: [{day: "2", id: 2, msg: 'txt'}]
    }];
    
    var newMessages = [
        {day: "1", id: 3, msg: 'txt'},
        {day: "1", id: 4, msg: 'txt'},
        {day: "2", id: 5, msg: 'txt'},
        {day: "3", id: 6, msg: 'txt'}
    ];
    
    function merge(oldMessages, newMessages) {
      for (var i=0; i<newMessages.length; i++) {
        var exists = false;
        for (var j=0; j<oldMessages.length; j++) {
        	if (oldMessages[j].day == newMessages[i].day) {
          	oldMessages[j].msgs.push(newMessages[i]);
            exists=true;
            break;
          }
        }
        if (!exists) {
        	oldMessages.push({'day':newMessages[i].day,'msgs':newMessages[i]});
        }
      }
      return oldMessages;
    }
    
    console.log(merge(oldMessages, newMessages));

Collectives™ on Stack Overflow

How to add one array object to another 2 dimensional array by key with lodash

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related