Add new object in JSON array

Question

I'm working with javascript and JSON. I have a JSON object like this one:

{"firstName":"John", "lastName":"Doe", "id":"1"}

In my case, I have a function like this one:

function addNewValues(jsonArray, firstName, lastName, id)

In case the "firstName" is not a match, I should create a new value in the array.

From

addNewValues({"firstName":"John", "lastName":"Doe", "id":"1"}, "Jane", 
"Doe", "2");

it should return:

[
{"firstName":"John", "lastName":"Doe", "id":"1"},
{"firstName":"Jane", "lastName":"Doe", "id":"2"}
]

How can I add this new position? I tried myObj.push({"firstName":firstName, "lastName":lastName }); without any success.

Thanks in advance.

JSON.parse your JSON, push the item and then JSON.stringify to have a JSON. Or work with array of objects and JSON.stringify when you have the need of JSON. — ADreNaLiNe-DJ
– ADreNaLiNe-DJ, Commented Jul 10, 2017 at 11:30
There's a much of confusion going on between JSON, arrays and objects here. An object doesn't have the push() method, an array has. You should be very careful with what you are doing - having both an array or an object being returned from your function will most probably lead to a mess. — baao
– baao, Commented Jul 10, 2017 at 11:32
@zoealonso: this is not a forum, don't change the title with [SOVLED], but rather accept an answer ;-) — Adrian Maire
– Adrian Maire, Commented Jul 11, 2017 at 8:39

Yordan Nikolov · Accepted Answer · 2017-07-10 11:46:38Z

If your json is a string, you have to parse it with JSON.parse and then put it into array if it not.

var array = [];

// with push
function addNewValues(firstName, lastname, id) {
  // check if firstName already exists
  if(array.filter(function(x) { return x.firstName===firstName; }).length===0) {
    array.push({
        'firstName': firstName,
        'lastName': lastname,
        'id': id
    });
  }
}

// with concat
// I would suggest you to use this method
function addNewValues1(arr, firstName, lastname, id) {
  if(arr.filter(function(x) { return x.firstName===firstName; }).length===0) {
    return arr.concat([{
        'firstName': firstName,
        'lastName': lastname,
        'id': id
    }]);
  }
  return arr;
}

addNewValues("Jahn", "Doe", "1");
addNewValues("Jane", "Doe", "2");
console.log(array);

// with concat
array = addNewValues1(array, "Foo", "Bar", "3");
console.log(addNewValues1(array, "Foo1", "Bar1", "4"));
console.log(array);

cнŝdk · Accepted Answer · 2017-07-10 11:52:15Z

You can use .some() method to test if the given array doesn't contain an object with this firstName, then push a new object with these properties.

This is how should be your code:

function addNewValues(jsonArray, firstName, lastName, id){
     if(!jsonArray.some(function(obj){
         return obj.firstName === firstName;
      })){
          jsonArray.push({"firstName": firstName, "lastName" : lastName, "id": id});
      };
}

Demo:

var jsonArray = [{"firstName":"John", "lastName":"Doe", "id":"1"}];

function addNewValues(jsonArray, firstName, lastName, id){
     if(!jsonArray.some(function(obj){
         return obj.firstName === firstName;
      })){
          jsonArray.push({"firstName": firstName, "lastName" : lastName, "id": id});
      };
}

addNewValues(jsonArray, "Jane", 
"Doe", "2");

console.log(jsonArray);

baao · Accepted Answer · 2017-07-10 13:07:04Z

To get that you can use below function. It will update the records if the firstname exists, or it will create a new entry in case it doesn't. Below function will find the first entry with given firstname.

let obj = {
    "firstName": "John",
    "lastName": "Doe",
    "id": "1"
};

function addNewValues(arr, firstName, lastName, id) {
    arr = Array.isArray(arr) ? arr : [arr];
    let obj = arr.find(v => v.firstName === firstName);
    if (! obj) {
        return arr.concat({firstName, lastName, id});
    }
    obj.lastName = lastName;
    obj.id = id;
    return arr;
}

console.log(addNewValues(obj, "Jane", "Foo", 3));

Abhishek Anand · Accepted Answer · 2017-07-11 10:06:32Z

Everything is ok with your code except the line

    addNewValues({"firstName":"John", "lastName":"Doe", "id":"1"}, "Jane", "Doe", "2");

You are supposed to pass array of JSON (assuming that you have written the function already), but right now you are passing JSON object only .

Try this instead

    addNewValues([{"firstName":"John", "lastName":"Doe", "id":"1"}], "Jane", "Doe", "2");

once you do this , the below mentioned line will execute without any error.

    myObj.push({"firstName":firstName, "lastName":lastName });

You can also check this working demo in jsfiddle

Alberto Trindade Tavares · Accepted Answer · 2017-07-10 11:30:38Z

0

In your call addNewValues, you should pass an array as the first parameter (you are passing an object instead):

var values = [{"firstName":"John", "lastName":"Doe", "id":"1"}];
addNewValues(values , "Jane", "Doe", "2");

answered Jul 10, 2017 at 11:30

Alberto Trindade Tavares

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Comments

Nilesh Khisadiya · Accepted Answer · 2017-07-10 11:34:52Z

Please see below code. Hope this will help to understand your problem. After adding new array, updated value showing in console.

You can read more about Javascript Array Methods: Unshift(), Shift(), Push(), And Pop()

var jsonArray=[{"firstName":"John", "lastName":"Doe", "id":"1"}];

function addNewValues(firstName, lastName, id){
// here you can check if exists or not
jsonArray.push({"firstName":firstName, "lastName":lastName,"id":id });
console.log(jsonArray);
return jsonArray;
}

<button type="button" onClick='addNewValues("Jane", 
"Doe", "2"); '>Click Me!</button>

Shiladitya · Accepted Answer · 2017-07-10 11:37:17Z

0

Here you go with the solution https://jsfiddle.net/52q9v57j/

var jsonArray = [{"firstName":"John", "lastName":"Doe", "id":"1"}];

addNewValues = function(jsonArray, firstName, lastName, id){
	return jsonArray.push(
  	{"firstName": firstName, "lastName": lastName, "id": id}
  );
}

addNewValues(jsonArray, "Jane", "Doe", "2"); 
console.log(jsonArray);

answered Jul 10, 2017 at 11:37

Shiladitya

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Comments

gaback · Accepted Answer · 2017-07-10 11:40:03Z

-1

newArray = [];
newArray.push(jsonArray);
function addNewValues(newArray, firstname, lastname, id){
    jsonArray.push({
        'firstName': firstname,
        'lastName': lastname,
        'id': id
    });
    return newArray;
}
newArray = addNewValues(newArray, 'Jane', 'Doe', '2');
// newArray now is array of 2 jsonObject

Hope this help.

edited Jul 10, 2017 at 11:40

answered Jul 10, 2017 at 11:31

gaback

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