combine json array into one json array by id

Question

I want to merge item and purchases array of json into one by matching their property value.

Here's the source :

{
    "item": [
        {
            "invoiceId": 1
        },
        {
            "invoiceId": 2
        },
        {
            "invoiceId": 3
        }
    ],
    "purchase": [
        {
            "id": "1",
            "date": "12/1/2014"
        },
        {
            "id": "2",
            "date": "12/1/2014"
        },
        {
            "id": "3",
            "date": "12/1/2014"
        }
    ]
}

I want to produce something like this :

{
    "combined": [
        {
            "invoiceId": 1,
            "id": "1",
            "date": "12/1/2014"
        },
        {
            "invoiceId": 2,
            "id": "2",
            "date": "12/1/2014"
        },
        {
            "invoiceId": 3,
            "id": "3",
            "date": "12/1/2014"
        }
    ]
}

How can I match the item.invoiceId with purchase.id?

Downgoat · Accepted Answer · 2015-04-09 03:45:23Z

2

Solution

assuming obj is your object

var new_obj = {combined:[]};
obj["purchase"].forEach(function(a) {
    obj["item"].forEach(function(b){ 
        if (+b["invoiceId"]===(+a["id"])) {
            a["invoiceId"] = b["invoiceId"] || 0;//WILL MAKE INVOICEID 0 IF IT IS NOT DEFINE. CHANGE 0 TO YOUR NEEDS
            new_obj.combined.push(a);
        }
    });
});

How it works

The first .forEach() loops through obj.purchase. Then we loop through obj.item To check if their is a matching invoiceId (if you don't need to make sure their is a matching invoiceId, use the alternate code). Then, we simply add a new value to the new_obj

The result (copied from console) is:

{
    "combined":[
        {
            "id":"1",
            "date":"12/1/2014",
            "invoiceId":1
        },
        {
            "id":"2",
            "date":"12/1/2014",
            "invoiceId":2
        },
        {
            "id":"3",
            "date":"12/1/2014",
            "invoiceId":3
        }
    ]
}

Alternative Code

Use this if you don't need to make sure, invoiceId is there

var new_obj = {combined:[]};

obj["purchase"].forEach(function(a){a["invoiceId"]=a["id"];new_obj.combined.push(a);});

edited Apr 9, 2015 at 3:45

answered Apr 9, 2015 at 3:26

Downgoat

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7 Comments

James Lemon Over a year ago

curious to know what is +a["a"] here

Downgoat Over a year ago

@JamesLemon That just converts it into an Number. It's shorthand for parseInt/parseFloat

Downgoat Over a year ago

@JamesLemon Simple fix, add a + before the b, I updated my answer. Here's your fiddle: jsfiddle.net/blue1086/ap417mde/1

James Lemon Over a year ago

just curious how the casting work. is it just add a + in any variable and it will become an integer?

Downgoat Over a year ago

@JamesLemon I'm guessing it thinks it's a math equation so it'll convert it. Also because multiplying *1 will convert it. Example '5'*1

|

Mritunjay · Accepted Answer · 2015-04-09 03:27:13Z

0

One way of achieving what you want will be

var result = {};

var getMatchingPurchase = function(invoiceId) {
    return data.purchase.filter(function(purchase) {
        return invoiceId == purchase.id; 
    })[0];
};

result.combined = data.item.map(function(invoice) {
    var purchase = getMatchingPurchase(invoice.invoiceId);
    return {
        invoiceId: invoice.invoiceId,
        id: purchase.id,
        date: purchase.date
    };
});

console.log(result);

It will print like bellow

{ combined:
   [ { invoiceId: 1, id: '1', date: '12/1/2014' },
     { invoiceId: 2, id: '2', date: '12/1/2014' },
     { invoiceId: 3, id: '3', date: '12/1/2014' } ] }

Note:- I'm using map and filter functions which are not supported in IE8. If you want to use in IE8 you have to use for loop.

answered Apr 9, 2015 at 3:27

Mritunjay

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2 Comments

James Lemon Over a year ago

says invoice id is my priority, will the id become null and the loop is still going?

Mritunjay Over a year ago

@JamesLemon do you mean if there is not matching purchase for an inovoice ?

JK ABC · Accepted Answer · 2015-04-09 15:15:27Z

0

If you have to support old browsers like IE8 (poor guy...), note that the native forEach might not be supported, in this case you can use lodash for cross-browser compatibility:

function getCombinedResult(source){
    var combinedList = [];
    _.each(source.item, function(item){
        _.each(source.purchase, function(purchase){
            if (item['invoiceId'].toString() != purchase['id'].toString()) return;
            var combinedItem = _.extend(item, purchase)
            combinedList.push(combinedItem);
        });
    })
    return {"combined": combinedList};
}

edited Apr 9, 2015 at 15:15

answered Apr 9, 2015 at 4:52

JK ABC

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2 Comments

Downgoat Over a year ago

.forEach is a 1.9 specification. Pretty much every browser nowadays should support it, even IE

JK ABC Over a year ago

you're right, it's fine since IE 9, editted to make it more clear

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