AJAX value from PHP returned as undefined with JSON

Question

I have an AJAX script updating a database via PHP.

I am then trying to return two variables back to the AJAX success function.

Currently, when alerting the data returned they are showing UNDEFINED.

When I return the JSON without stating the part of the array I require, the array displays in full. But only when I state specifically which value from the array I wish to use, I seem to get undefined on both values.

How should I manage these values returned from the PHP?

The AJAX

success: function(data) {
    $('#'+data.toUpdate).html(data.quant);
    $('#'+data.toUpdate).addClass('updated_grn');
    alert('quant:' + data.quant + '\nid:' + data.toUpdate);  
}

The PHP

if ($query) {
    echo json_encode(array("toUpdate" => $toUpdate, "quant" => $quant));
}

The Result

Ajax returns Undefined

When I alert(data) this is returned:

Returned data

The full php

$itemid   = ($_POST['itemid']);
$quant    = ($_POST['quant']);
$toUpdate = ($_POST['toUpdate']);

$sql = "UPDATE items_list
        SET `stock_level` = '$quant'
        WHERE item_id = '$itemid'";

$query = mysql_query($sql);

if ($query) {
    echo json_encode(array("toUpdate" => $toUpdate, "quant" => $quant));
}

The full AJAX

$.ajax({
    type:     'POST',
    url:      url,
    dataType: 'html',
    data: {
        itemid:   itemid,
        quant:    quant,
        toUpdate: toUpdate
    },
    beforeSend: function() {
        $('#'+id+'_num')
            .html("<img src='xxxxxxx.com/home/secure/images/gif/ajax-loader.gif'></img>");
    },
    success: function(data) {
        alert(data);
        //  $('#'+data.toUpdate).html(data.quant);
        //  $('#'+data.toUpdate).addClass('updated_grn');
        //  alert('quant:' + data.quant + '\nid:' + data.toUpdate);
    }
});

What happens if you change dataType: 'html' to dataType: 'json' — Darren
– Darren, Commented May 25, 2014 at 23:54
oh wow. Don't i feel silly now. Thank you, if you answer i shall tick yours as correct, many thanks. @Darren — Derple
– Derple, Commented May 25, 2014 at 23:56
@StuartWickenden It's a pleasure :) I too ran into that issue once upon a time and felt like a complete idiot! — Darren
– Darren, Commented May 25, 2014 at 23:58

Darren · Accepted Answer · 2014-05-25 23:57:39Z

2

Just change dataType: 'html' to dataType: 'json' :)

answered May 25, 2014 at 23:57

Darren

13.1k4 gold badges44 silver badges81 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Ladislav Gallay · Accepted Answer · 2014-05-25 23:45:20Z

0

Make sure that $query is true. I would also do die() so nothing else is in output:

 if ($query) {
    die(json_encode(array("toUpdate" => $toUpdate, "quant" => $quant)));
}

You can always check what you get from PHP:

success: function(data) {
        alert(data);
        $('#'+data.toUpdate).html(data.quant);
        $('#'+data.toUpdate).addClass('updated_grn');
        alert('quant:'+data.quant+'\nid:'+data.toUpdate);  
}

answered May 25, 2014 at 23:45

Ladislav Gallay

4886 silver badges15 bronze badges

2 Comments

Derple Over a year ago

updated, the data returns in the array when alert(data). Illustrated in question.

Ladislav Gallay Over a year ago

Use jQuery.parseJSON like this: var obj = jQuery.parseJSON(data); alert(obj.quant);

wpjr · Accepted Answer · 2015-10-11 08:08:53Z

0

FYI. I found this problem when using WordPress (4.3.1) and tried to load json data to D3.json function inside WordPress. json_encode(some_array) did not work but returned undefined. It returned a single integer value but not any array. UTF-8 check or anything else did not help.

Then incidently I closed the php ajax function by wp_die() command, it was missing there. And voila!, this suddenly works, json_encode returns array fine.

Hopefully this helps someone.

answered Oct 11, 2015 at 8:08

wpjr

111 bronze badge

Collectives™ on Stack Overflow

AJAX value from PHP returned as undefined with JSON

3 Answers 3

Comments

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related