sorting and manipulating json objects , javascript

Question

I have a json response in the form :

some_array = [{
ios: "110"
rate_pl: "PlanC"
ref_site: "N/A"
reservation_id: "12709034"
},{
ios: "121"
rate_pl: "SomePlan"
ref_site: "FB"
reservation_id: "1273034
},{
ios: "141"
rate_pl: "PlanC"
ref_site: "Tweet"
reservation_id: "143034
}];

How do i group a particular attribute say 'rate_pl' and also add the values if the ios which related to that particular rate_pl.

example --> Result should be:

someObject = [
    {PlanC: ['ios':251]},              //(110+141 = 251)
    {SomePlan: ['ios':121]}
    ]; 

Answer 1

You could use reduce function, like this:

var result = some_array.reduce(function(prev, cur) {
    if (prev[cur.rate_pl] === undefined) {        
        prev[cur.rate_pl] = [];
        prev[cur.rate_pl].push({ ios : parseInt(cur.ios, 10) });
    } else {
        prev[cur.rate_pl][0].ios += parseInt(cur.ios, 10);
    }
    return prev;
}, []);

Little demo .

Answer 2

As others have stated it is a bit confusing what you want since you are mixing arrays and objects.

Just to help you going, if you are looking for this response:

{
    PlanC: {
        ios: 251
    },
    SomePlan: {
        ios: 121
    }
}

You can use this code:

var new_object = {};
for (var i = 0; i < some_array.length; i++) {
    if (angular.isUndefined(new_object[some_array[i].rate_pl])) {
        new_object[some_array[i].rate_pl] = {ios: 0};
    }
    new_object[some_array[i].rate_pl].ios += parseInt(some_array[i].ios);
}

If you actually want some of the objects to be arrays that should be easy to modify.

Answer 3

The first thing to do is to group the array by rate_pl using _.groupBy :

var groups = _.groupBy(some_array,'rate_pl')

This will return an object with the keys being the distinct rate_pl values and the values will be an array of all the objects having that rate_pl:

{
   PlanC: [ { ios: '110', etc }, {iod: '141' etc } ],
   SomePlan: [ { ios: 121 etc } ]
}

The next thing to do is to transform the values into what you want (or something similar to what you want). This can be done using _.mapObject which was introduced in Underscore 1.8:

var result = _.mapObject(groups, function(rates){
    return {
        ios: _.reduce(rates, function(memo, rate){
            return memo + parseInt(rate.ios);
        }, 0)
    }
});

This will give you:

{
   PlanC: { ios: '251' },
   SomePlan: { ios: 121 }
}