jQuery Validator Plugin - check for existing Username/Email in mysql database

Question

I've successfully created a form that submits and adds users to a mysql database, and form validation with 'jQuery Validator' plugin works great for everything except checking to see if the username already exists in the database...

I've just spent about 8 hours reading and trying to figure out a way to define a new method with the 'jQuery Validator' plugin. I just can't seem to understand how I would go about checking the database for the entered username or email and return whether it already exists or not using jQuery.

My code:

<script src="../assets/js/main.js"></script>
<script src="../assets/js/ajax.js"></script>
<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.11.0/jquery.validate.min.js"></script>
<!-- FORM VALIDATION -->
<script type="text/javascript">


    jQuery.validator.addMethod("checkExists", 
function(value, element) {
    //No idea what to call here
}, 
"Username already exists."
);


        //<![CDATA[
        $(window).load(function(){
        $("form").validate({
        rules: {
            username: {minlength: 3, required: true, checkExists: true},
            email: {email: true, required: true},
            pass1: {minlength: 3, required: true},
            pass2: {minlength: 3, required: true, equalTo: "#pass1"},
            country: {required: true},
            tandc: {required: true},
        },
        messages: {
        username:   {required: "You need to enter a Username."},
        email:      {required: "You need to enter an Email Address."},
        pass1:      {required: "You need to enter a Password."},
        pass2:      {required: "You need to enter your password again.", equalTo: "Your passwords don't match."},
        country:    {required: "You need to tell us where you live."},
        tandc:      {required: "You need to read and agree to the Terms and Conditions to use CGE."}
        },


        showErrors: function(errorMap, errorList) {
        $.each(this.successList, function(index, value) {
        return $(value).popover("hide");
        });
        return $.each(errorList, function(index, value) {
        var _popover;
        console.log(value.message);
        _popover = $(value.element).popover({
        trigger: "manual",
        placement: "right",
        content: value.message,
        template: "<div class=\"popover\"><div class=\"arrow\"></div><div class=\"popover-inner\"><div class=\"popover-content\"><p></p></div></div></div>"
        });
        _popover.data("popover").options.content = value.message;
        return $(value.element).popover("show");
        });
        }
        });
        });//]]>
</script>

If anyone clever could please amend my code to show me how I should have done it, it would be a great help - I feel like I'm about to go crazy!

Thanks in advance, can't wait to see the solution :-)

---

EDIT - This is my current code

Nothing seems to happen at all, I feel like I'm closer though:

CURRENT CODE:

signup.php

    $(window).load(function(){
            $("form").validate({
            rules: {
                username: {minlength: 3, required: true},
                email: {email: true, required: true, remote: {url: "./validation/checkUnameEmail.php", type : "post"}},
                pass1: {minlength: 3, required: true},
                pass2: {minlength: 3, required: true, equalTo: "#pass1"},
                country: {required: true},
                tandc: {required: true}
},

checkUnameEmail.php

<?php
    include_once(".../php_includes/db_conx.php");
    $email = urldecode($_POST['email']);
    $result = mysqli_query($db_conx, "SELECT * FROM users WHERE email = '$email' LIMIT 1;");
    $num = mysqli_num_rows($result);
    if($num == 0){
        echo "true";
    } else {
        echo "E-Mail-Adresse schon registriert.";
    }
    mysqli_close($db_conx);
?>

*db_conx.php*

<?php
$db_conx = mysqli_connect("localhost", "root", "root", "membership");
//Evlauate the connection
if (mysqli_connect_errno()){
    echo mysqli_connect_error();
    exit();
}
?>

Answer 1

$.validator.addMethod("checkExists", function(value, element)
{
    var inputElem = $('#register-form :input[name="email"]'),
        data = { "emails" : inputElem.val() },
        eReport = ''; //error report

    $.ajax(
    {
        type: "POST",
        url: validateEmail.php,
        dataType: "json",
        data: data, 
        success: function(returnData)
        {
            if (returnData!== 'true')
            {
              return '<p>This email address is already registered.</p>';
            }
            else
            {
               return true;
            }
        },
        error: function(xhr, textStatus, errorThrown)
        {
            alert('ajax loading error... ... '+url + query);
            return false;
        }
    });

}, '');

OR

You can use the remote method instead which allows you to do remote checks: http://docs.jquery.com/Plugins/Validation/Methods/remote

Eg.

    $("#yourFormId").validate({
            rules: {
                email: {
                    required: true,
                    email: true,
                    remote: {
                        url: "checkUnameEmail.php",
                        type: "post"
                     }
                }
            },
            messages: {
                email: {
                    required: "Please Enter Email!",
                    email: "This is not a valid email!",
                    remote: "Email already in use!"
                }
            }
        });

checkUnameEmail.php //Eg.

    <?php
    $registeredEmail = array('[email protected]', '[email protected]', '[email protected]', '[email protected]', '[email protected]');

    $requestedEmail  = $_REQUEST['email'];

    if( in_array($requestedEmail, $registeredEmail) ){
        echo 'false';
    }
    else{
        echo 'true';
    }
    ?>

Answer 2

js code

username: {
        required: true,
        minlength: 5,
        remote: '/userExists'
       },

Php code to check if exist and return messages

public function userExists()
{
    $user = User::all()->lists('username');
    if (in_array(Input::get('username'), $user)) {
        return Response::json(Input::get('username').' is already taken');
    } else {
        return Response::json(Input::get('username').' Username is available');
    }
}