Not getting posted data using AJAX

Question

i want to be able to check if a user eamil exists on "blur()" with AJAX by posting the textbox data to php, i can see the data posted when i use firebug but i keep getting this error: Undefined index: data, i've tried so hard but haven't been able to resolve this issue yet. This is the javascript:

$(document).ready(function() {
$('#regEmail').blur(function() {
            var Email = $('#regEmail').val();
            var data = '{Email:' + Email + '}';
            $.ajax({
                type: "POST",
                url: "register.php",
                data: data,
                contentType: "application/json; charset=utf-8",
                dataType: "json",
                success: function (response) {
                    var result = response.exists;
                    if (result == true) {
                        alert('Email already exists!');
                        return;
                    }
                    else {
                        alert("Does not exist!");
                    }
                }
            });
        });
});

And this is the php code:

if (isset($_POST['data']))
    {
        $db = new mysqli("localhost", "xxxx", "xxxxxxx", "xxxxxxx");

        $data = $_POST['data'];
        json_decode($data);

        $Email = $data->fetch_assoc();
        $Email = $Email["Email"];

        $sql = "SELECT COUNT(*) as isExisting FROM users WHERE user_email='$Email'"; 
        $sql_result = $db->query($sql);
        $result = $sql_result->fetch_assoc();

        if ($result["isExisting"] > 0)
        {
            $response = json_encode(array('exists' => true));
        } else {
            $response = json_encode(array('exists' => false));
        }

        echo $response;
        print json_encode($_POST);
    }

I added "if (isset($_POST['data']))" to check if the post data has been set but apparently it hasn't.

Answer 1

$_POST is for key/value formatted, URL encoded data. You're sending raw JSON which is different. With your current Javascript, you would need to use $HTTP_RAW_POST_DATA to get the JSON on the PHP side.

This will do it:

        var data = { Email : Email };
        $.ajax({
            type: "POST",
            url: "register.php",
            data: { data : JSON.stringify(data) },
            dataType: "json",
            success: function (response) {
                var result = response.exists;
                if (result == true) {
                    alert('Email already exists!');
                    return;
                }
                else {
                    alert("Does not exist!");
                }
            }
        });

Changes:

• data variable to a Javascript object (not JSON)
• send as form encoded POST data, with one input (data) that is the JSON encoded version of the data object.
• removed the JSON content type

On the PHP side, your JSON will be decoded to an object, so use:

$data = $_POST['data'];
$email = json_decode($data);
$Email = $Email->Email;

You can use the array syntax, but only if you set the second argument for json_decode() to true . json_decode() does not update the variable passed as an argument, you must capture the return value.

Answer 2

With the jQuery.ajax method, the data parameter is supposed to be a JSON object. You should write instead :

var data = { 'Email': Email };
$.ajax({
    type: "POST",
    url: "register.php",
    data: data,
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: function (response) {
        var result = response.exists;
            if (result == true) {
                alert('Email already exists!');
                return;
            }
            else {
                alert("Does not exist!");
            }
        }
    }
);

And then you can use the email value server-side by accessing $_POST['Email'] .