Array in hidden variable changes to string

Question

I'm setting an array to a hidden field using JavaScript. However, the issue is that the array gets converted to a string on form submit when I catch it using PHP.

This is the code that sets the hidden input field value:

document.getElementById("hiddenFieldId").value = arrayFromJS;

Is there any workaround for this?

Actually the problem is earlier I had a select box which sent it's values nicely on form submit. But now I've got a custom select box using JS which sets comma separated values in a hidden field... So in a nutshell I want that input field to act like a pseudo-select box

More code is needed. What is the array you are setting? How are you submitting the form? — Michael Berkowski
– Michael Berkowski, Commented Aug 14, 2013 at 13:07
I'd prefer that nothing changes at the server end. I'm submitting the form using POST — Batman
– Batman, Commented Aug 14, 2013 at 13:52

Andreas Louv · Accepted Answer · 2013-08-14 13:17:21Z

1

You should JSON encode/decode the value:

On the client side you use JSON.stringify to encode the array:

document.getElementById("hiddenFieldId").value = JSON.stringify(arrayFromJS);

And then on the server side you can use json_decode:

$arr = json_decode($_POST['hiddenFieldId']); // Fetch the data from POST / GET

foreach ( $arr as $value ) {
    // iterate the array on the server side.
}

unset($arr); // Remember to unset the $arr variable

If you know you are handeling a simple array (with string only) you can join the string in javascript and explode/split it php:

document.getElementById("hiddenFieldId").value = arrayFromJS.join('/:/');

PHP:

$arr = explode('/:/', $_POST['hiddenFieldId']);

To support older browser you can use this JSON plugin to the front end: https://github.com/douglascrockford/JSON-js

edited Aug 14, 2013 at 13:17

answered Aug 14, 2013 at 13:11

Andreas Louv

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