Replace null values to empty values in a JSON OBJECT

Question

Hi I've got a JSON object provided by an ajax request.

Some of the values inside the json appears as null, but I want an empty String instead

My sample of code :

$.post("/profil_process/wall/preview-post.php",param, function (data){
    // this does not work
    JSON.stringify(data, function(key, value) { return value === "" ? "" : value });
    $('#previewWall').html(getPostWall(data.type,data.titre,data.url,data.description,data.media,data.photo_auteur,data.nom_auteur,data.url_auteur,data.date_publication)).fadeIn();
    $(".bouton-vertM").show();
    $("#wLoader").hide();
},'json');

Any ideas?

Your code says that if the value is an empty string, then the empty string should be returned; if it's anything else, then the value should be returned as-is. Thus, it's exactly equivalent to just return value; — Pointy
– Pointy, Commented Mar 5, 2014 at 16:30
You realize that data doesn't really change even if you stringify the object like that ? — adeneo
– adeneo, Commented Mar 5, 2014 at 16:35
@Kuma: Where did you get that code from? It doesn't appear in the revision history. — BoltClock
– BoltClock, Commented Mar 7, 2014 at 1:26
@BoltClock, I believe it was edited first by him (to narrow down the code) before I applied my edit. See one answer here that contains the same code. — Rey Libutan
– Rey Libutan, Commented Mar 7, 2014 at 1:35

double-beep · Accepted Answer · 2021-07-21 08:13:33Z

45

Your function should be like this:

function (key, value) {
    return (value === null) ? "" : value;
}

If the value is null, then it returns an empty string.

edited Jul 21, 2021 at 8:13

double-beep

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answered Mar 5, 2014 at 16:31

Amin Abu-Taleb

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7 Comments

Pointy Over a year ago

value == null will be true when value is either null or undefined, so there's no need for any further comparison.

adeneo Over a year ago

@Anthony - As I commented on the answer, this doesn't change anything, strings are immutable, and the object surely isn't updated just because you decided to stringify it.

Kevin Farrugia Over a year ago

This could be refactored to return value || "";

kook Over a year ago

Should not use return value || "" . 0 or false will be empty string, either.

Julix Over a year ago

@KevinFarrugia not that, for reason that @kook mentioned, but you could do null-coalescing: return value ?? '' without those weird side effects.

|

Багдаулет Сайын · Accepted Answer · 2019-05-27 13:42:49Z

21

If you can replace null-s with empty strings on serialized string, do something like this:

data = JSON.parse(JSON.stringify(data).replace(/\:null/gi, "\:\"\""));

edited May 27, 2019 at 13:42

Багдаулет Сайын

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answered Mar 5, 2014 at 16:36

gradosevic

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6 Comments

adeneo Over a year ago

Don't you think it would be better to use the built in replacer argument rather than a string replace ?

gradosevic Over a year ago

I don't see a reason why this would be bad idea, in cases where we use serialized JSON string anyway and when it wouldn't affect performance

adeneo Over a year ago

But JSON.stringify has a built in replacer as the second argument, which is what the OP is using. Don't you think it would be a better idea to use the built in replacer argument than to create your own for no apparent reason ?

gradosevic Over a year ago

Yeah, you're right. I think about this as clean on-line-solution, but I definitely agree with you that built-in solutions should always have priority over custom solutions.

Evan Carroll Over a year ago

This is a horrible idea.

|

adeneo · Accepted Answer · 2014-03-05 16:53:46Z

Here's how you should be doing it, replacing the objects values with empty strings, not stringifying it

$.post("/profil_process/wall/preview-post.php",param, function (data){

    (function removeNull(o) {
        for(var key in o) {
            if( null === o[key] ) o[key] = '';
            if ( typeof o[key] === 'object' ) removeNull(o[key]);
        }
     })(data);

     $('#previewWall').html(
          getPostWall(
              data.type,
              data.titre,data.url,
              data.description,
              data.media,
              data.photo_auteur,
              data.nom_auteur,
              data.url_auteur,
              data.date_publication
          )  // ^^^ why not just pass the entire object ?
    ).fadeIn();

    $(".bouton-vertM").show();
    $("#wLoader").hide();

},'json');

Moshood Aminu · Accepted Answer · 2019-01-10 19:18:31Z

2

For anyone still looking for a solution.

Used this in my angular 2 app to remove all null values returned by my db query.

Create an angular 2 function in the component

    replacer(i, val) {
     if ( val === null ) 
     { 
        return ""; // change null to empty string
     } else {
        return val; // return unchanged
     }
    }

Or Javascript function

    function replacer(i, val) {
     if ( val === null ) 
     { 
        return ""; // change null to empty string
     } else {
        return val; // return unchanged
     }
    }

Then use the function in JSON.stringify method

    JSON.stringify(result, this.replacer)

answered Jan 10, 2019 at 19:18

Moshood Aminu

2911 silver badge5 bronze badges

Comments

wondim · Accepted Answer · 2020-09-11 05:25:10Z

2

I recommend you the check the return type of the Ajax because it determines how to remove null.

If it is string, you can use this:

data = data.replace(/null/g, '""');  //Stays as string

Or:

data = JSON.parse(data);    // Turns to a JSON object

If it is json object, then you can use this:

data = JSON.stringify(data).replace(/null/g, '""');  //Turns to string

edited Sep 11, 2020 at 5:25

answered Sep 11, 2020 at 5:20

wondim

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Comments

Sanan Ali · Accepted Answer · 2021-07-08 05:45:51Z

1

Here is a simple code that will convert all null values into an empty string

let myObject = {
  "id":1,
  "name": "Ali",
  "address":null,
  "phone":null,
  "age":22
}
Object.keys(myObject).map(function (key, index) {
                if (myObject[key] == null) {
                    myObject[key] = "";
                }
            });
console.log(myObject); 

// output
/* {
  "id": 1,
  "name": "Ali",
  "address": "",
  "phone": "",
  "age": 22
}  */

answered Jul 8, 2021 at 5:45

Sanan Ali

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Comments

CFrank · Accepted Answer · 2021-01-23 03:16:04Z

0

Underscore mapObject gave me the most compact solution. Here's a complete example:

$ npm install underscore

import _, { map, each } from 'underscore';
var x = {a:null, b:1, c:'c', d:null}
var y = _.mapObject(x, function(val, key) {
            return val || '';
        });
console.log('No nulls:', y)

No nulls: {a:"", b:1, c:"c", d:""}

edited Jan 23, 2021 at 3:16

answered Jan 23, 2021 at 3:10

CFrank

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Comments

Adam Foody · Accepted Answer · 2022-04-15 12:51:40Z

Little late to the party buy hey/ho.

The below function is the exact opposite of what you need, so just reverse engineer :D

In order to swap empty string's or strings with spaces in JSON we will need to iterate through the keys and check if a value contains an empty string.

You can complete this, easily with the .trim method. We basically check, if the length of the string trimmed, (without spaces) is equal to 0. If so we will add the same key to our new object but add a null value instead. You could also remove the length in the trim call and check if obj[keys].trim == ''.

      function myFunction(obj){
      const newObj = {}

      for(keys in obj){
      if(obj[keys].trim().length == 0){
      newObj[keys] = null; 
      }
      else{
      newObj[keys] = obj[keys];
      }
   }

   return newObj;

 }

Manish Pal · Accepted Answer · 2022-09-15 13:19:22Z

0

Here is the correct way to do it in JS

let data = {
    "msg": "Success",
    "data": [
        {
            "firstName": "Manish",
            "lastName": "Pal",
            "age": 23
        },
        {
            "firstName": "Deepak",
            "lastName": "Gupta",
            "age": null
        }
    ],
    "salary": [
        {
            "id": "1",
            "type": "SD",
            "amount": 1000000
        },
        {
            "id": "2",
            "type": "C",
            "ok": null
        }
    ]
};

let mainResponse = {};

const replaceNull = (value) => {
    return (value == null) ? "" : value
}
//Parse Json and check for null
const removeNullFromJson = (object1, jsonObj) => {
    for (const [key, value] of Object.entries(object1)) {
        if (Array.isArray(value)) {
            jsonObj[key] = [];
            for (let i = 0; i < value.length; i++) {
                jsonObj[key].push(removeNullFromJson(value[i], {}))
            }
        }
        else if (typeof value == "object" && value != null) {
            jsonObj[key] = removeNullFromJson(value, {})
        }
        else {
            jsonObj[key] = replaceNull(value);
        }
    }
    return jsonObj
}

console.log(removeNullFromJson(data, mainResponse))

answered Sep 15, 2022 at 13:19

Manish Pal

1

1 Comment

Community Over a year ago

Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.

Pichet Thantipiputpinyo · Accepted Answer · 2015-05-14 21:37:12Z

-1

Hope this help

var List = [];


$.post("/profil_process/wall/preview-post.php",param, function (data){

jQuery.each(data, function (key, value) {
                List.push({
                    ReportId : value.ReportId,
                    ReportType: CheckNullReturnBlank(value.ReportType),
                    ReportName: CheckNullReturnBlank(value.ReportName),
                    Description : CheckNullReturnBlank(value.Description)
                })
            });   },'json');



function CheckNullReturnBlank(item) {
    return item = (item == null) ? '' : item;
}

answered May 14, 2015 at 21:37

Pichet Thantipiputpinyo

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Comments

akshay · Accepted Answer · 2016-06-29 10:50:02Z

-1

You can replace null values to empty by below code in java-script

var remove_empty = function ( target ) {
  Object.keys( target ).map( function ( key ) {
    if ( target[ key ] instanceof Object ) {
      if ( ! Object.keys( target[ key ] ).length && typeof target[ key ].getMonth !== 'function') {
        target[ key ] = "";
      }
      else {
        remove_empty( target[ key ] );
      }
    }
    else if ( target[ key ] === null ) {
       target[ key ] = "";
    }
  } );
  return target;
};

you can read more about Object.keys

answered Jun 29, 2016 at 10:50

akshay

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Comments

Julieto Ompad · Accepted Answer · 2016-04-14 03:40:45Z

-2

function returnblank(item){
  if(item == null){
    return "";
  }else{
    return item;
  }
}

answered Apr 14, 2016 at 3:40

Julieto Ompad

15

2 Comments

A J Over a year ago

A little explanation would not hurt.

Lilith Daemon Over a year ago

Please try and add an explanation to your answer.

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