How to create JSON array and push values into it in node.js

Question

I am trying to push key, value in array and then converting it into JSON using JSON.stringify(). But it is not working.

My node.js code:

var jarray=[];
var json1=""; 

for (var i=0; i<jsonObj["Masters"]['Customer'].length; i++){

     var name= jsonObj["Masters"]['Customer'][i];
      var cust_name=name['Customer_Name'];
      var cust_code=name['Customer_Code'];

    connection.query("SELECT code FROM ((SELECT ccode AS code FROM customermaster WHERE companyid='AXWPM1658D') UNION ALL (SELECT scode AS code FROM suppliermaster WHERE companyid='AXWPM1658D') UNION ALL (SELECT stcode AS code FROM stockmaster WHERE companyid='AXWPM1658D') UNION ALL (SELECT gcode AS code FROM generalledger2 WHERE companyid='AXWPM1658D') UNION ALL (SELECT bcode AS code FROM bankmaster WHERE companyid='AXWPM1658D'))p  where code='"+cust_code+"' ", function(err, rows, fields) {
     if (!err){

        var item ={"customer_name":cust_name ,"customer_code": cust_code };

      jarray.push(item);

    }
      else{
        console.log('Error while performing Query.'+err);
          }
    });

    }

json1=JSON.stringify({jarray:jarray});

var jsonObj1 = JSON.parse(json1); 
console.log("Json:"+jsonObj1);
console.log("arr length:"+jsonObj1.jarray.length);

It prints:

Json:{ jarray: [] }
arr length:0

My question is how to push values in array and convert it into JSON array?

JSON.stringify should be just JSON.stringify(jarray). No need of the curly braces again. — Dhanush Gopinath
– Dhanush Gopinath, Commented Dec 2, 2015 at 7:36
your code is synchronous but database query is asynchronous. So before getting result from database, your code executes. Thats way j array is empty as you initialized var jarray=[]; — Hiren S.
– Hiren S., Commented Dec 2, 2015 at 7:39
If i write json1=JSON.stringify(jarray); var jsonObj1 = JSON.parse(json1); console.log("Json:"+jsonObj1); then it prints : [] [] — Amit Shirke
– Amit Shirke, Commented Dec 2, 2015 at 7:43

jkoestinger · Accepted Answer · 2015-12-02 07:45:11Z

1

What do you use to make SQL requests? It looks like it has an asynchronous behaviour. If so, it can be the reason on why your array is still empty when you stringify it. By the way, making SQL request in a loop is not very effective. Perhaps is it better to fetch all results with one SQL request, this will also make it easier to stringify in the callback

answered Dec 2, 2015 at 7:45

jkoestinger

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1 Comment

Amit Shirke Over a year ago

to make sql requests: var mysql = require('mysql'); var connection = mysql.createConnection({ host : '', user : '', password : '', database : '' }); connection.connect();

Hiren S. · Accepted Answer · 2015-12-02 07:52:07Z

1

Use this:

var jarray = [];
var json1 = "";

var async = require('async');

async.forEachLimit(jsonObj["Masters"]['Customer'], 1, function(customer, callback) {

    var name = customer;
    var cust_name = name['Customer_Name'];
    var cust_code = name['Customer_Code'];

    connection.query("SELECT code FROM ((SELECT ccode AS code FROM customermaster WHERE companyid='AXWPM1658D') UNION ALL (SELECT scode AS code FROM suppliermaster WHERE companyid='AXWPM1658D') UNION ALL (SELECT stcode AS code FROM stockmaster WHERE companyid='AXWPM1658D') UNION ALL (SELECT gcode AS code FROM generalledger2 WHERE companyid='AXWPM1658D') UNION ALL (SELECT bcode AS code FROM bankmaster WHERE companyid='AXWPM1658D'))p  where code='" + cust_code + "' ", function(err, rows, fields) {
        if (!err) {

            var item = {
                "customer_name": cust_name,
                "customer_code": cust_code
            };

            jarray.push(item);
            callback();

        } else {
            callback(err);
            console.log('Error while performing Query.' + err);
        }
    });



}, function(err) {
    if (err) {
        console.log(err);
    } else {

        json1 = JSON.stringify({
            jarray: jarray
        });

        var jsonObj1 = JSON.parse(json1);
        console.log("Json:" + jsonObj1);
        console.log("arr length:" + jsonObj1.jarray.length);
    }
})

answered Dec 2, 2015 at 7:52

Hiren S.

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7 Comments

Amit Shirke Over a year ago

Hiren S. It's working but when i print console.log("Json:" + jsonObj1); it prints: [Object Object]

Hiren S. Over a year ago

Yes because it is JSON Object. thats why . USE console.log("Json:" + JSON.stringify( jsonObj1));

Amit Shirke Over a year ago

Thany you so much Hiren S... but what if i want to access customer_name. How can i access particular value from that json array?

Amit Shirke Over a year ago

I have to access that array outside of that for loop and function(err).

Hiren S. Over a year ago

jsonObj1.jarray[indexValue].customer_name

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