Get data from complex Json structure using NodeJs

Question

json Structure:

    {
    "id" : "1",
    "Data" : [
    {
            "name" : "abc",

        },
        {
            "name" : "option1",
            "position" : [
                {
                    "name" : "option1",
                    "status" : [
                        {
                            "code" : "0",
                            "value" : "OFF"
                        },
                        {
                            "code" : "1",
                            "value" : "ON"
                        }
                    ]
                }]
        }   ]   
}

Here,I want to get the data from above complex Json structure.How to do that, Have tried below code but giving error like; error: uncaughtException: Cannot read property 'status' of undefined

function myfunc(req,res){
var collectionname  = db.collection("col1");
collectionname.find({}).each(function(err, doc) {
   if(doc != null)
    {
        var fdata = [];
        for(var i =0;i<doc.Data.length;i++){
            fdata.push(doc.Data[i].position.status);
            }
        console.log("fdata............",fdata);
    }
});
}

Please help with the same.

Position is an array, so can't access it using position.status. You can use position[0].status if there is only one object in the position array — fawee
– fawee, Commented Mar 12, 2018 at 9:39
@TB.M doc.Data[i].position[0].status But you need to think a bit about this. The fact that it's an array means that it can contain any number (including 0) of objects with or without a status property. Can you be sure there's always at least one object? If there are more than one, can you be sure the first one is always the one you want? — Lennholm
– Lennholm, Commented Mar 12, 2018 at 10:19
yeah,It will not always 0 element,I hav updated the array in question and below i got the answer also.Thanks for understanding. — TB.M
– TB.M, Commented Mar 12, 2018 at 10:24

Liberateur · Accepted Answer · 2018-03-15 17:04:30Z

1

You can use foreach for prevent length undefined.

function myfunc(req,res)
{
    let collectionname = db.collection("col1");
    collectionname.find({}).each(function(err, doc)
    {
        if(doc != null)
        {
            let fdata = [];

            for(let i in doc.Data)
            {
                for(let j in doc.Data[i].position)
                {
                    fdata.push(doc.Data[i].position[j].status);
                }
            }

            console.log("fdata............", fdata);
        }
    });
}

@MikaelLennholm have right, for(let i in doc.Data) works but not recommanded, be careful not to use it in prototyped or object-built arrays.

EDIT:

function myfunc(req,res)
{
    db.collection('col1').find({}).each(function(err, doc)
    {
        if(err)
        {
            console.log('[INFOS] Request fail, more details:\n', err);
        }
        else if(doc)
        {
            let fdata = [];

            if(doc.Data && doc.Data.length)
            {
                for(let i = doc.Data.length-1; i >= 0; i--)
                {
                    if(doc.Data[i].position && doc.Data[i].position.length)
                    {
                        for(let j = doc.Data[i].position.length-1; j >= 0; j--)
                        {
                            if(doc.Data[i].position[j].status)
                            {
                                fdata = fdata.concat(doc.Data[i].position[j].status);
                            }
                        }
                    }
                }
            }

            console.log("[INFOS] Datas:\n", fdata);
        }
    });
}

edited Mar 15, 2018 at 17:04

answered Mar 12, 2018 at 10:12

Liberateur

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12 Comments

TB.M Over a year ago

And if we want to include name along with status .how we can do?

Lennholm Over a year ago

NEVER use in for arrays, it's going to cause weird bugs

TB.M Over a year ago

Than,how we can archive the result?

TB.M Over a year ago

I m using In but it is not iterating,,I want to iterate the array ??How we can do that ?

Liberateur Over a year ago

For add name, you can just edit fdata.push(doc.Data[i].position[j].status); by fdata.push(doc.Data[i].position[j]);

|

Thiện Sinh · Accepted Answer · 2018-03-12 09:54:26Z

1

im a newbie at nodejs, hope this's correctly

//I assume this is a object or you can convert from string to object
var data = {
    "id": "1",
    "Data": [
        {
            "name": "option1",
            "position": [
                {
                    "name": "option1",
                    "status": [
                        {
                            "code": "0",
                            "value": "OFF"
                        },
                        {
                            "code": "1",
                            "value": "ON"
                        }
                    ]
                }]
        }]
}

var statusArr = data.Data[0].position[0].status;
console.log(...statusArr);

Result: { code: '0', value: 'OFF' } { code: '1', value: 'ON' }

answered Mar 12, 2018 at 9:54

Thiện Sinh

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1 Comment

TB.M Over a year ago

but same way I am doing it is not happening..If u check in my code.

Anusha kurra · Accepted Answer · 2018-03-12 09:44:40Z

0

Parse through position array as well

function myfunc(req,res){
var collectionname  = db.collection("col1");
collectionname.find({}).each(function(err, doc) {
   if(doc != null)
    {
        var fdata = [];

        for(var i =0;i<doc.Data.length;i++){
        for(var j =0;j<doc.Data[i].position.length;j++){
            fdata.push(doc.Data[i].position[j].status);
            }
        }
        console.log("fdata............",fdata);
    }

}); }

answered Mar 12, 2018 at 9:44

Anusha kurra

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2 Comments

TB.M Over a year ago

error: uncaughtException: Cannot read property 'length' of undefined.

Anusha kurra Over a year ago

is position array always,

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