SyntaxError: JSON.parse: unexpected non-whitespace character after JSON data

Question

I have the following AJAX call:

$('#FonykerUsernameRegister').blur(function(){
            if($(this).val().length > 2) {
                alert($(this).val());
                $.ajax({
                    url: '<?php echo $html->url('/fonykers/validate_username',true); ?>' + '/' + $(this).val(),
                    dataType: 'json',
                    type: 'POST',
                    success: function(response) {
                        if(!response.ok) {
                            $(this).addClass('error');
                            error.html(response.msg);
                            error.fadeIn();
                        } else {
                            if($(this).is('.error')) {
                                alert('im in');
                                $(this).removeClass('error');
                            }
                            $(this).addClass('ok');
                        }
                    },
                    error:function (xhr, ajaxOptions, thrownError){
                        alert('You fail');
                        alert(xhr.statusText);
                        alert(thrownError);
                    } 
                });        
            } else {
               error.html('Username must have at least 3 characters');
               error.fadeIn();
               $(this).addClass('error');
            }
        });

And this is the method it's calling:

function validate_username($username) {
        $this->layout = 'ajax';
        $response = array();
        $fonyker = $this->Fonyker->find('first', array(
            'conditions' => array('Fonyker.username' =>  $username)
        ));

        if(!strlen($username) > 2) {
            $response = json_encode(array('ok' => false, 'msg' => 'Username must have at least 3 characters'));
        } else if(!preg_match('"^[a-zA-Z0-9]+$"', $username)) {
            $response = json_encode(array('ok' => false, 'msg' => 'Username must be alphanumeric'));
        } else if ($fonyker) {
            $response = json_encode(array('ok' => false, 'msg' => 'Username is already in use'));
        } else {
            $response = json_encode(array('ok' => true, 'msg' => ''));
        }

        echo $response;
    }

In the AJAX call it always goes to the error part and outputs that error, and I don't see any whitespaces in my PHP code. Any thoughts?

EDIT:

What was happening is that CakePHP was echoing the entire view in the response, but not really the view but the error screen.

If you need AJAX methods in your controller that do not require a view you must set the $this->autoRender property on the controller method to false before doing anything.

the error is for a non-whitespace character, not a whitespace character. Also, could you post the resultant json? Use Firebug (or the like) to observe the response. — Jonathan Fingland
– Jonathan Fingland, Commented Jul 20, 2011 at 19:42
Looking at the response I see that cake is sending back the entire page HTML with the JSON response, because it says it requires a view. — 8vius
– 8vius, Commented Jul 20, 2011 at 19:52
You shouldn't be echoing out things from within your controller method. That's what views are for. The technically correct way to approach this would be to set a response variable here, and echo it in the view. Its a little tedious to create a whole new file to echo out one line, so you can also return $response from this method and you'll get the response in your ajax call. Both are preferable to echoing in a controller method I would think. — Jeff Ryan
– Jeff Ryan, Commented Jan 11, 2013 at 7:31

Bo Persson · Accepted Answer · 2012-06-24 12:56:29Z

2

There may have been an echo in your ajax function. Check it and remove any echo, print, debug from the ajax function.

When you return json data, you can't echo anything.

edited Jun 24, 2012 at 12:56

Bo Persson

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answered Jun 24, 2012 at 6:49

Hanif

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Comments

Jonathan Fingland · Accepted Answer · 2011-07-20 20:53:10Z

1

Based on OP's comment response:

Although I'm not specifically familiar with the CakePHP way of doing it, when using ZendApplication, one of the first things to do is make an empty layout. Normal responses get placed in the default layout, while ajax responses get placed in the empty layout.

In your controller methods, set $this->layout to your empty layout to override the default where applicable.

See http://www.balistupa.com/blog/2009/07/how-to-change-cakephp-layout/ for more specific instructions

answered Jul 20, 2011 at 20:53

Jonathan Fingland

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2 Comments

8vius Over a year ago

In the end it was setting $this->autoRender = false; on the controller method to set that it doesn't have a view, you were the most help, Jonathan, thank you, I'll edit my question with the answer but I'll accept yours for setting me on the right path.

Jonathan Fingland Over a year ago

Glad I could help, even if it wasn't the specific solution. Thanks as well for editing your question so it can help others in the future

Passionate Engineer · Accepted Answer · 2011-07-21 08:05:03Z

0

Did you check ajax.ctp file in layouts folder inside view folder?

answered Jul 21, 2011 at 8:05

Passionate Engineer

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Comments

ttemple · Accepted Answer · 2012-11-30 17:22:19Z

0

When using ColdFusion for development, be sure to turn debugging OFF or else it can cause this issue

answered Nov 30, 2012 at 17:22

ttemple

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Comments

eadjei · Accepted Answer · 2013-03-20 21:31:30Z

0

Your client/ajax call expects a JSON dataType from the server. Now you need to make sure the server is returning a JSON dataType, else change the request to request to reflect what the service is returning.

To investigate this, use firebug to see what you are getting as response. I just got this error and I fixed it.

answered Mar 20, 2013 at 21:31

eadjei

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Comments

Cocuba · Accepted Answer · 2013-10-07 21:50:22Z

0

i had the same problem, but i solved with "$this->autoRender = false;" in the function!

answered Oct 7, 2013 at 21:50

Cocuba

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