Updating a JSON object using Javascript

Question

How can i update the following JSON object dynamically using javascript or Jquery?

var jsonObj = [{\'Id\':\'1\',\'Username\':\'Ray\',\'FatherName\':\'Thompso         


        

Answer 1

I took Michael Berkowski's answer a step (or two) farther and created a more flexible function allowing any lookup field and any target field. For fun I threw splat (*) capability in there incase someone might want to do a replace all. jQuery is NOT needed. checkAllRows allows the option to break from the search on found for performance or the previously mentioned replace all.

function setVal(update) {
    /* Included to show an option if you care to use jQuery  
    var defaults = { jsonRS: null, lookupField: null, lookupKey: null,
        targetField: null, targetData: null, checkAllRows: false }; 
    //update = $.extend({}, defaults, update); */

    for (var i = 0; i < update.jsonRS.length; i++) {
        if (update.jsonRS[i][update.lookupField] === update.lookupKey || update.lookupKey === '*') {
            update.jsonRS[i][update.targetField] = update.targetData;
            if (!update.checkAllRows) { return; }
        }
    }
}


var jsonObj = [{'Id':'1','Username':'Ray','FatherName':'Thompson'},  
           {'Id':'2','Username':'Steve','FatherName':'Johnson'},
           {'Id':'3','Username':'Albert','FatherName':'Einstein'}]

With your data you would use like:

var update = {
    jsonRS: jsonObj,
    lookupField: "Id",
    lookupKey: 2, 
    targetField: "Username",
    targetData: "Thomas", 
    checkAllRows: false
    };

setVal(update);

And Bob's your Uncle. :) [Works great]

Answer 2

A plain JavaScript solution, assuming jsonObj already contains JSON:

Loop over it looking for the matching Id, set the corresponding Username, and break from the loop after the matched item has been modified:

for (var i = 0; i < jsonObj.length; i++) {
  if (jsonObj[i].Id === 3) {
    jsonObj[i].Username = "Thomas";
    break;
  }
}

Here it is on jsFiddle.

Here's the same thing wrapped in a function:

function setUsername(id, newUsername) {
  for (var i = 0; i < jsonObj.length; i++) {
    if (jsonObj[i].Id === id) {
      jsonObj[i].Username = newUsername;
      return;
    }
  }
}

// Call as
setUsername(3, "Thomas");

Answer 3

JSON is the JavaScript Object Notation. There is no such thing as a JSON object. JSON is just a way of representing a JavaScript object in text.

So what you're after is a way of updating a in in-memory JavaScript object. qiao's answer shows how to do that simply enough.