jQuery AJAX Call to PHP Script with JSON Return

Question

I've been smashing my head against a brick wall with this one, i've tried loads of the solutions on stackoverflow but can't find one that works!

Basically when I POST my AJAX the PHP returns JSON but the AJAX shows Undefined instead of the value:

JS:

  /* attach a submit handler to the form */
  $("#group").submit(function(event) {

  /* stop form from submitting normally */
  event.preventDefault();

  /*clear result div*/
  $("#result").html('');

  /* get some values from elements on the page: */
  var val = $(this).serialize();

  /* Send the data using post and put the results in a div */
  $.ajax({
      url: "inc/group.ajax.php",
      type: "post",
      data: val,
  datatype: 'json',
      success: function(data){
            $('#result').html(data.status +':' + data.message);   
            $("#result").addClass('msg_notice');
            $("#result").fadeIn(1500);           
      },
      error:function(){
          $("#result").html('There was an error updating the settings');
          $("#result").addClass('msg_error');
          $("#result").fadeIn(1500);
      }   
    }); 
});

PHP:

  $db = new DbConnector();
  $db->connect();
  $sql='SELECT grp.group_id, group_name, group_enabled, COUNT('.USER_TBL.'.id) AS users, grp.created, grp.updated '
        .'FROM '.GROUP_TBL.' grp '
        .'LEFT JOIN members USING(group_id) '
        .'WHERE grp.group_id ='.$group_id.' GROUP BY grp.group_id';

    $result = $db->query($sql);     
    $row = mysql_fetch_array($result);
    $users = $row['users'];
    if(!$users == '0'){
        $return["json"] = json_encode($return);
        echo json_encode(array('status' => 'error','message'=> 'There are users in this group'));
    }else{

        $sql2= 'DELETE FROM '.GROUP_TBL.' WHERE group_id='.$group_id.'';
        $result = $db->query($sql2);

        if(!$result){
            echo json_encode(array('status' => 'error','message'=> 'The group has not been removed'));
        }else{
            echo json_encode(array('status' => 'success','message'=> 'The group has been removed'));
        }
    }

JSON Result from firebug:

{"status":"success","message":"success message"}

AJAX Displays the JSON result as Undefined and I dont have a clue why. I have tried displaying adding dataType='json' and datatype='json'. I have also tried changing it to data.status and data['status']: still no joy though.

Any help would be really appreciated.

Set a "application/json" header `header('Content-Type: application/json');` — hank, Oct 03 '13 at 09:12
`datatype` should have a capital `T`: `dataType: 'json'`. In theory it should infer the type from the response, so this may not fix the issues. — Rory McCrossan, Oct 03 '13 at 09:13
Either @hank or @Rory's suggestion should be enough. If the correct mimetype is set, there is no need to specify the `dataType` — Johan, Oct 03 '13 at 09:15

score 48 · Accepted Answer · edited May 23 '17 at 12:26

48

Make it dataType instead of datatype.

And add below code in php as your ajax request is expecting json and will not accept anything, but json.

header('Content-Type: application/json');

Correct Content type for JSON and JSONP

The response visible in firebug is text data. Check Content-Type of the response header to verify, if the response is json. It should be application/json for dataType:'json' and text/html for dataType:'html'.

edited May 23 '17 at 12:26

Community

1
1

answered Oct 03 '13 at 09:17

Sorter

8,190
5
52
63

Hi Thanks for this! most of the posts say that header('Content-Type: application/json'); isnt required! obviously it is! – Steven Marks Oct 03 '13 at 09:41
I'm very glad if this helped you. I know how it feels when something like this doesn't work. And yes I've too banged my wall on the head for this in the past :D but with a different server side language. – Sorter Oct 03 '13 at 09:44
I do have one script that still doesn't work, I am deleting a row from a table and then returning json however the json seems to have the ID from the deleted row in front of it: `38{"status":"success","message":"The group has been removed"}` – Steven Marks Oct 03 '13 at 09:53
You have to print and see what php is sending and fix accordingly. – Sorter Oct 03 '13 at 09:57
This was the solution to my problem – AdRock Oct 21 '16 at 13:46

score 5 · Answer 2 · answered Oct 03 '13 at 09:19

5

I recommend you use:

var returnedData = JSON.parse(data);

to convert the JSON string (if it is just text) to a JavaScript object.

answered Oct 03 '13 at 09:19

Shakti Patel

3,482
4
19
27

if you use success callback, you already have resulting string parsed into javascript object and put as a parameter in the success callback function. – Simon Polak May 07 '14 at 19:06

score 3 · Answer 3 · answered Oct 03 '13 at 09:25

3

Use parseJSON jquery method to covert string into object

var objData = jQuery.parseJSON(data);

Now you can write code

$('#result').html(objData .status +':' + objData .message);

answered Oct 03 '13 at 09:25

mujaffars

1,327
12
33

score 2 · Answer 4 · answered Oct 03 '13 at 09:16

2

try to send content type header from server use this just before echoing

header('Content-Type: application/json');

answered Oct 03 '13 at 09:16

Pankaj Sharma

1,765
1
16
22

score 2 · Answer 5 · answered Feb 13 '14 at 21:07

2

Your datatype is wrong, change datatype for dataType.

answered Feb 13 '14 at 21:07

Arleal

96
3

jQuery AJAX Call to PHP Script with JSON Return

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