Create JSON object dynamically via JavaScript (Without concate strings)

Question

I have this JSON data:

{
    "employees": [
        {
            "firstName": "John",
            "lastName": "Doe"
        },
        {
            "firstName": "Anna",
            "lastName": "Smith"
        },
        {
            "firstName": "Peter",
            "lastName": "Jones"
        }
    ]
}

Suppose I don't know how many columns and rows of employees I have, how do I create this object in JavaScript (Without concate strings)? Assume that I get each row in "onGeneratedRow" method, and I need to push each column (firstName, lastName) to the '{}' brackets.

var viewData = { 
    employees : [] 
};

var rowNum = -1; 

function onGeneratedRow(columnsResult)
{
    rowNum = rowNum + 1;
    viewData.employees.push({});    
    columnsResult.forEach(function(column) {                  
    var columnName = column.metadata.colName;
    viewData.employees[rowNum][columnName] = column.value;  });
}

This questions does not make sense to me at present, can you explain further, where is your data coming from and in what format. Are you just adding to existing data or creating all of it from scratch. Maybe you can create a jsfiddle to demonstrate what the problem you are having is.Is your question really just, how to access data within an array/ or javascript object? And lets be clear about the data, JSON or Javascript object: stackoverflow.com/questions/8294088/javascript-object-vs-json — Xotic750
– Xotic750, Commented May 12, 2013 at 12:20
assume "columnName" is "firstName" and "column.value" is the value (for example: "John"). I just need to know how to push them dynamically into the brackets ('{}') — ohadinho
– ohadinho, Commented May 12, 2013 at 12:24
@ohadinho it is unclear what is your input data strucuture (json) columnsResult — Kamil Kiełczewski
– Kamil Kiełczewski, Commented Apr 25, 2019 at 10:24

Waqar Alamgir · Accepted Answer · 2013-05-12 12:28:10Z

200

This is what you need!

function onGeneratedRow(columnsResult)
{
    var jsonData = {};
    columnsResult.forEach(function(column) 
    {
        var columnName = column.metadata.colName;
        jsonData[columnName] = column.value;
    });
    viewData.employees.push(jsonData);
 }

edited May 12, 2013 at 12:28

answered May 12, 2013 at 12:15

Waqar Alamgir

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6 Comments

Xotic750 Over a year ago

How did you know that the OP does not need to count the rows with ´rowNum´?

Waqar Alamgir Over a year ago

push does not need row number

Waqar Alamgir Over a year ago

because json generation does not need count, more you can always use .length to get rows.

Xotic750 Over a year ago

I never said that JSON generation does. It was more the case that you state "This is what you need!", but I wanted to know how you knew that count was not needed by the OP, or did you just assume? Your answer does not generate JSON btw.

bob.mazzo Over a year ago

@WaqarAlamgir - that's exactly what I needed at this moment. Cheers!

|

Xotic750 · Accepted Answer · 2016-12-15 04:13:37Z

137

Perhaps this information will help you.

var sitePersonel = {};
var employees = []
sitePersonel.employees = employees;
console.log(sitePersonel);

var firstName = "John";
var lastName = "Smith";
var employee = {
  "firstName": firstName,
  "lastName": lastName
}
sitePersonel.employees.push(employee);
console.log(sitePersonel);

var manager = "Jane Doe";
sitePersonel.employees[0].manager = manager;
console.log(sitePersonel);

console.log(JSON.stringify(sitePersonel));

edited Dec 15, 2016 at 4:13

answered May 12, 2013 at 12:32

Xotic750

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Comments

Adrian Wiik · Accepted Answer · 2017-12-17 11:31:49Z

This topic, especially the answer of Xotic750 was very helpful to me. I wanted to generate a json variable to pass it to a php script using ajax. My values were stored into two arrays, and i wanted them in json format. This is a generic example:

valArray1 = [121, 324, 42, 31];
valArray2 = [232, 131, 443];
myJson = {objArray1: {}, objArray2: {}};
for (var k = 1; k < valArray1.length; k++) {
    var objName = 'obj' + k;
    var objValue = valArray1[k];
    myJson.objArray1[objName] = objValue;
}
for (var k = 1; k < valArray2.length; k++) {
    var objName = 'obj' + k;
    var objValue = valArray2[k];
    myJson.objArray2[objName] = objValue;
}
console.log(JSON.stringify(myJson));

The result in the console Log should be something like this:

{
   "objArray1": {
        "obj1": 121,
        "obj2": 324,
        "obj3": 42,
        "obj4": 31
   },
   "objArray2": {
        "obj1": 232,
        "obj2": 131,
        "obj3": 443
  }
}

Can I stress the usefulness in properly spacing the code you submit here? It's much harder to read without spacing.

Tirolel · Accepted Answer · 2019-02-15 13:45:17Z

2

JavaScript

var myObj = {
   id: "c001",
   name: "Hello Test"
}

Result(JSON)

{
   "id": "c001",
   "name": "Hello Test"
}

edited Feb 15, 2019 at 13:45

Tirolel

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answered Feb 4, 2019 at 6:25

Ishan Lakshitha

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