Question

    echo "<form method='post' action='regprocess.php' id='registerform'>";
        echo '<fieldset class="register">';
        echo"<h2>Register</h2>";
            echo "<ul>";
                    echo '<li><label for="FirstName">First Name: </label> <input type="text" name="FirstName" id="FirstName"></li>';
                    echo '<li><label for="LastName">Last Name: </label> <input type="text" name="LastName" id="LastName"></li>';
                    echo '<li><label for="Email">Email: </label><input type="email" name="Email" id="Email"></li>';
                    echo '<li><label for="Username">Username: </label><input type="text" name="Username" id="Username"></li>';
                    echo '<li><input type="button" id="check_username_availability" value="Check Availability"></li>';  
                    echo '<div id="username_availability_result"></div>'; 
                    echo '<li><label for="Password">Password: </label><input type="password" name="Password" id="Password"></li>';
                    echo '<li><input type="submit" value="Register"></li>';
                    echo "</ul>";
        echo "</fieldset>";
        echo "</form>";


<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js"></script>

<SCRIPT LANGUAGE="JAVASCRIPT" TYPE="TEXT/JAVASCRIPT">
$(document).ready(function() {  

        var checking_html = 'Checking...';  

        //when button is clicked  
        $('#check_username_availability').click(function(){  
            //run the character number check  
                $('#username_availability_result').html(checking_html);  
                check_availability();  
        });  

  });  

//function to check username availability  
function check_availability(){  

        //get the username  
        var username = $('#username').val();  

        //use ajax to run the check  
        $.post("check_username.php", { username: username },  
            function(result){  
                //if the result is 1  
                if(result == 1){  
                    //show that the username is available  
                    $('#username_availability_result').html(username + ' is Available');  
                }else{  
                    //show that the username is NOT available  
                    $('#username_availability_result').html(username + ' is not Available');  
                }  
        });  

}
</script>


<?php
$conn = new mysqli('sapphire', 'cgreenheld', '', 'cgreenheld_dev');
$username = mysqli_real_escape_string($conn, $_POST['Username']);  

//mysql query to select field username if it's equal to the username that we check '  
$usernameresult = 'Select Username from User where Username = "'. $username .'"'; 
$uresult = $conn->query($usernameresult); 

//if number of rows fields is bigger them 0 that means it's NOT available '  
if($uresult->num_rows==1) {  
    //and we send 0 to the ajax request  
    echo 0;  
}else{  
    //else if it's not bigger then 0, then it's available '  
    //and we send 1 to the ajax request  
    echo 1;  
}  
?>

Hi everyone, I’m trying to check if a username is in the database, and I’m not sure quite what’s wrong with my code, when it retrieves the stuff from the database it just always shows “undefined is not avaliable” so for some reason it’s not retrieving the username, wondering if anyone could help me? I’m really stuck.. The php is in a different file just for anyone who wanted to know.

Answer 1

You have an Uppercase ‘Username’ id attribute on your input and you are selecting it with a lowercase ‘username’ in jquery:

echo '<li><label for="Username">Username: </label><input type="text" name="Username" id="Username"></li>';

var username = $('#username').val();

and

you are posting lowercase ‘username’ to php and trying to access it with an uppercase ‘Username’

$.post("check_username.php", { username: username }, 

$username = mysqli_real_escape_string($conn, $_POST['Username']);  

Set them all to lowercase or uppercase and you should be OK