JSON.stringify JS array to send to PHP and json_decode in PHP

Question

I have a form with different sections, when a user saves a section it is sent via JS to another file where it saves it as a session variable in PHP until the rest of the form is filled out and then it is all processed together.

Here is my JS that sends my array:

console.log(price_array);
price_array = JSON.stringify(price_array);
var formData = new FormData();
formData.append("price_array", price_array);
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function(){
    if(this.readyState == 4 && this.status == 200){
        //session set
    }
};
xmlhttp.open("POST", "myFile.php", true);
xmlhttp.send(formData);

So at this point I can see my array exactly the way I want when I log it in the console before I stringify it and send it.

(2) [empty, Array(0)]1: Array(0)EUR: Array(0)cost: "100"discount: "10"margin: "10"z1: "0"z2: "10"z3: "20"z4: "30"z5: "40"z6: "50"z7: ""z8: ""length: 0__proto__: Array(0)GBP: Array(0)cost: "100"discount: "10"margin: "10"z1: "0"z2: "10"z3: "20"z4: "30"z5: "40"z6: "50"z7: ""z8: ""length: 0__proto__: Array(0)attribute: "default"model_no: "test"length: 0__proto__: Array(0)length: 2__proto__: Array(0)

My PHP file then is very simple it is just:

if(isset($_POST['price_array'])){
    $_SESSION['price_array'] = json_decode($_POST['price_array']);
    echo 'session_set';
    exit();
}

However, when I do a var_dump($_SESSION['price_array']); it appears blank. Can anyone explain why this is happening or what I can do about it?

array (size=2)
  0 => null
  1 => 
    array (size=0)
      empty

Edit

I did this:

console.log(price_array);
var json = JSON.stringify(price_array);
console.log(json);

And got this:

(2) [empty, Array(0)]
1: Array(0)
EUR: [cost: "1830.00", discount: "31.00", margin: "28.00", z1: "0.00", z2: "110.00", …]
GBP: [cost: "1525.00", discount: "31.00", margin: "28.00", z1: "50.00", z2: "0.00", …]
attribute: "1-1_"
model_no: "FMS 20M"
length: 0
__proto__: Array(0)
length: 2
__proto__: Array(0)

[null,[]]

So when it is being stringified something is going wrong is this because it is a multidimensional array?

No need to stringify it as JSON the decode it again via PHP. You can send the array directly if you suffix the name of the property you append to `formdata` with `[]`. See https://stackoverflow.com/questions/16104078/appending-array-to-formdata-and-send-via-ajax/28434829#28434829 — Mitya, Jul 08 '19 at 10:24
@Utkanos tried changing my JS to this:`console.log(price_array);//price_array = JSON.stringify(price_array);var formData = new FormData();for(var i=0; i string 'undefined' (length=9)1 => string '' (length=0)` — Paddy Hallihan, Jul 08 '19 at 10:29
You don't need the loop - just `formData.append('price_array[]', price_array);` — Mitya, Jul 08 '19 at 10:31
@Utkanos that doesn't work either it just returns `array (size=1) 0 => string ',' (length=1)` — Paddy Hallihan, Jul 08 '19 at 10:33

score 0 · Accepted Answer · answered Jul 08 '19 at 11:50

0

The issue was stringifying a multidimensional array, changed this to an object and it worked as expected.

Instead of declaring it like:

var myVar = [];

I just changed it to:

var myVar = {};

answered Jul 08 '19 at 11:50

Paddy Hallihan

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JSON.stringify JS array to send to PHP and json_decode in PHP

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