how to use JSON.stringify and json_decode() properly

Question

Im trying to pass a mulitidimensional Javascript array to another page on my site by:

using JSON.stringify on the array
assigning the resultant value to an input field
posting that field to the second page
using json_decode on the posted value
then var_dump to test
(echo'ing the posted variable directly just to see if it came through at all)

Javascript on page one:

var JSONstr = JSON.stringify(fullInfoArray);
document.getElementById('JSONfullInfoArray').value= JSONstr;

php on page two:

$data = json_decode($_POST["JSONfullInfoArray"]);
var_dump($data);

echo($_POST["JSONfullInfoArray"]);

The echo works fine but the var_dump returns NULL

What have I done wrong?

This got me fixed up:

$postedData = $_POST["JSONfullInfoArray"];
$tempData = str_replace("\\", "",$postedData);
$cleanData = json_decode($tempData);
var_dump($cleanData);

Im not sure why but the post was coming through with a bunch of "\" characters separating each variable in the string

Figured it out using json_last_error() as sugested by Bart which returned JSON_ERROR_SYNTAX

Check the content of `$_POST["JSONfullInfoArray"]`. If something doesn't parse `json_code` will just return `null`. Also use `json_last_error()` to try and find what went wrong. — Bart, Apr 13 '13 at 09:25
A little bit HTML of the form would help too. Look into the request using your browser's inspector, do you see what you expect? — UltraInstinct, Apr 13 '13 at 09:33
@Bart see edit above, you got me where I needed to be, throw up an answer and Ill accept it :), thank you very much — Wesley Smith, Apr 13 '13 at 10:05
The answer in here worked for me (and all the other 'answers' below didn't!). — Chris Rae, Apr 02 '15 at 22:50

score 61 · Answer 1 · answered Mar 07 '18 at 11:54

61

When you save some data using JSON.stringify() and then need to read that in php. The following code worked for me.

json_decode( html_entity_decode( stripslashes ($jsonString ) ) );

Thanks to @Thisguyhastwothumbs

answered Mar 07 '18 at 11:54

S. A. Malik

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Ok, this is like the right answer and what I was looking for. Saved me a couple of hours of disgusting trial and error. – MarkSkayff Jan 24 '19 at 19:32
Thanks this is work for me!!! ... In $request["reporthead"] data as string which is from javascript $tempData = \html_entity_decode(stripslashes ($request["reporthead"])); $reportheaddata = json_decode($tempData, true); – Priyanka Ahire Dec 23 '20 at 12:30

user1881928 · Answer 2 · 2014-07-01T18:03:20.880

34

When you use JSON stringify then use html_entity_decode first before json_decode.

$tempData = html_entity_decode($tempData);
$cleanData = json_decode($tempData);

edited Jul 01 '14 at 18:03

answered Mar 26 '14 at 10:27

user1881928

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worth noting in wp I used the above with stripslashes within the html_entity_decode to make work : – treyBake Jan 22 '18 at 14:27

Bart · Accepted Answer · 2014-10-25T19:49:39.380

27

You'll need to check the contents of $_POST["JSONfullInfoArray"]. If something doesn't parse json_decode will just return null. This isn't very helpful so when null is returned you should check json_last_error() to get more info on what went wrong.

edited Oct 25 '14 at 19:49

answered Apr 13 '13 at 10:42

Bart

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Yuv · Answer 4 · 2016-06-04T05:38:22.863

11

None of the other answers worked in my case, most likely because the JSON array contained special characters. What fixed it for me:

Javascript (added encodeURIComponent)

var JSONstr = encodeURIComponent(JSON.stringify(fullInfoArray));
document.getElementById('JSONfullInfoArray').value = JSONstr;

PHP (unchanged from the question)

$data = json_decode($_POST["JSONfullInfoArray"]);
var_dump($data);

echo($_POST["JSONfullInfoArray"]);

Both echo and var_dump have been verified to work fine on a sample of more than 2000 user-entered datasets that included a URL field and a long text field, and that were returning NULL on var_dump for a subset that included URLs with the characters ?&#.

edited Jun 04 '16 at 05:38

answered Jun 04 '16 at 00:47

Yuv

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I also had to use `urldecode` on PHP for it to work properly. – Albion S. Mar 13 '17 at 08:37
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As @Albion points out, the string needs to be URI decoded before `json_decode` is invoked. `json_decode(urldecode($_POST["JSONfullInfoArray"]));` – Aurovrata Jul 31 '17 at 13:11

score 8 · Answer 5 · edited Sep 24 '14 at 08:28

8

stripslashes(htmlspecialchars(JSON_DATA))

edited Sep 24 '14 at 08:28

Gerard de Visser

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answered Sep 24 '14 at 07:12

LOVEPIN

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I am not sure why `htmlspecialchars()` must there. It will convert the quote character ( `"` ) to `"` which is mean can't be processed by `json_decode()`. I am sure `JSON` format must be something like `{"key":"value"}`, but by using `htmlspecialchars()` it will convert to `{"key":"value"}` how come `json_decode()` processing it? – Bayu Oct 04 '16 at 06:53

score 3 · Answer 6 · edited Jan 22 '18 at 11:10

3

jsonText = $_REQUEST['myJSON'];

$decodedText = html_entity_decode($jsonText);

$myArray = json_decode($decodedText, true);`

edited Jan 22 '18 at 11:10

Jobin

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answered Jan 22 '18 at 10:30

KRISHNA KANT SINGH

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score 0 · Answer 7 · answered Mar 02 '20 at 07:21

0

I don't how this works, but it worked.

$post_data = json_decode(json_encode($_POST['request_key']));

answered Mar 02 '20 at 07:21

user10971804

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how to use JSON.stringify and json_decode() properly

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