How to iterate through empty array or object

Question

I have an object or array like below: "[{},{},{},{},{},{},{},{},{\"subject\":\"Math\"},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{\"subject\":\"Chemistry\"},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{}]"

as well: [{},{},{},{},{},{},{},{},{"subject":"Math"},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{"subject":"Chemistry"},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{}]

when i am iterating it using foreach loop it show " Invalid argument supplied for foreach() in C:\wamp64\www\eschool\cms\admin\scripts\time-table-add-submit.php on line 11 " May be due to the empty value at the beginning and at the end. but I want to iterate it somehow how to do that. Heres my code: JavaScript:

var timeTableSub = [
       {"subject": timeTableSub1},
       {"subject": timeTableSub2},
       ... Like Wise....
       {"subject": timeTableSub42}
];
var jsonArray = JSON.stringify(timeTableSub);

$.ajax({
        url: "scripts/time-table-add-submit.php",
        type: "POST",
        dataType: 'html',
        data:{
            'arrayList': jsonArray
        },
        success: function (data) {
            data = $.trim(data);
            $("#tempDiv").html(data);
        }
    });

PHP:

<?php
$arrayList = json_encode($_POST['arrayList'], TRUE);

echo $arrayList."<br>";
$newArray = json_decode($arrayList);
echo $newArray."<br>";




foreach ($newArray as $key => $value)
{
      echo $key . " => " . $value . "<br>";
}

?>

you don't need $arrayList = json_encode($_POST['arrayList'], TRUE); because what you've sent from the browser is already JSON. And therefore you should be writing $newArray = json_decode($_POST['arrayList']); instead later on as well — ADyson
– ADyson, Commented May 20, 2020 at 12:16
thanx @ADyson now I'm getting the result but empty value lost. Is there a way it should print like "subject: " if it is empty — full_stack_developer
– full_stack_developer, Commented May 20, 2020 at 12:33

jmcgrory · Accepted Answer · 2020-05-20 12:18:16Z

1

You appear to be stringifying the data twice, once on the front end during the request with JSON.stringify and once more when receiving the POST object by encoding it once more.

Removing either would fix this issue.

answered May 20, 2020 at 12:18

jmcgrory

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7 Comments

full_stack_developer Over a year ago

following php is not working too. <?php $arrayList = $_POST['arrayList']; foreach ($arrayList as $key => $value) { echo $key . " => " . $value . "<br>"; } ?>

full_stack_developer Over a year ago

could you please send me the code to do it right. Thanx

jmcgrory Over a year ago

Okay so imagine encoding or stringifying your object as packing the data in a box. What you were doing by stringifying/encoding twice is packing the data into 2 boxes, but only unpacking once (with your json_decode). When I said to remove either the JSON.stringify or json_encode, you removed the json_encode (packing) AND the json_decode (unpacking). What that meant was you went from unpacking it once from 2 boxes (1 box still left), to unpacking it NO times from 1 box (1 box still left), i.e. same issue. Adding your json_decode back in would fix it.

full_stack_developer Over a year ago

I understood what you advised me. for example I'm doing this: hello=encode1=encode2=decode2 and the data is still in the form of ecoded1.

full_stack_developer Over a year ago

Now i'll doing it right and getting what I want as specified.

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