Question

What I am trying to do is validate whether an email address is in the database or not. My CheckEmailAddress checks if the email is in the database and it seems to work(rewrite it if needed). The problem is when I post my JSON email data from my JQuery function it always returns true when there should be a false if the email is entered in the database.

JQUERY:

$('#checkemail').click(function() {
    $.post('http://' +  location.host + '/buyme/include/getemailaddress.php', 
        {'email':'[e-mail]'},  function(res){
        var obj = JSON.parse(res);
        alert(obj)
    });
});

PHP

<?PHP
    require_once("membership.php");
    $membership = new Membership();
    $val = $_POST["email"];;
    $result = $membership->CheckEmailAddress(trim($val));
    echo json_encode($result); //output [e-mail]   
?>

function CheckEmailAddress($email_address) {
    $connection = mysql_connect('localhost:3306','root','')or die('Error connecting');
    mysql_select_db('buyme') or die('Connection not working properly');     
    $query = "SELECT email_address from users where email_address='$email_address'";
    $result = mysql_query($query, $connection);
    $row = mysql_fetch_assoc($result);

            $emailInUse = 'false';
    if(!$row || $row["email_address"] == '') {
        $emailInUse = 'true';
    }else{
        $emailInUse = 'false';  
    }

    return $emailInUse;
}

if anything needs correction please update my code so i can test thanks

UPDATE:

    try {
    $pdo = new PDO('mysql:dbname=buyme;host=localhost:3306', 'root', '', 
        $options = array (
        PDO::ATTR_ERRMODE,  PDO::ERRMODE_EXCEPTION
    ));
    $email_address = '[e-mail]';

    $stmt = $pdo->prepare("SELECT email_address
            FROM users 
            WHERE email_address=:email_address");
    $stmt->execute(array('email_address'=>$email_address));
    $rows = $stmt->fetchObject();

    echo empty($rows->email_address) ? "" : $rows->email_address; // $row["email_address"];

}catch (PDOException $e) {
    die('error: ' . $e->getMessage());      
} 

Answer 1

The issue is your TRUE & FALSE assignments are returning strings & not TRUE or FALSE values. Meaning they will always essentially be seen as TRUE because they are strings that contain values. A FALSE will always contain nothing. Also, you are doing an OR by doing || when it should be an AND by doing &&. So this snippet of code:

if(!$row || $row["email_address"] == '') {
    $emailInUse = 'true';
}else{
    $emailInUse = 'false';  
}

Should be rewritten like this:

if(!$row && $row["email_address"] == '') {
    $emailInUse = TRUE;
}else{
    $emailInUse = FALSE;  
}

And the final function would look like this:

function CheckEmailAddress($email_address) {
    $connection = mysql_connect('localhost:3306','root','')or die('Error connecting');
    mysql_select_db('buyme') or die('Connection not working properly');     
    $query = "SELECT email_address from users where email_address='$email_address'";
    $result = mysql_query($query, $connection);
    $row = mysql_fetch_assoc($result);

    if(!$row && $row["email_address"] == '') {
        $emailInUse = TRUE;
    }else{
        $emailInUse = FALSE;  
    }

    return $emailInUse;
}

That said, I would recommend avoiding an else statement by doing this:

    $emailInUse = FALSE;        
    if(!$row || $row["email_address"] == '') {
        $emailInUse = TRUE;
    }

    return $emailInUse;

Might not seem like a big difference, but from my experience, initing values like this with default values saves you headaches in the long run. Might not mean much in this script, but if you are a beginning programmer it’s a habit I recommend you getting into early on.

EDIT WITH ADDITIONAL PERSPECTIVE: Also, I just re-read your post. You seem to want to return the words “true” and “false”? Bad habit. Let the function return a logically TRUE or FALSE as I explained & then act on it in your main code. So this coding:

<?PHP
    require_once("membership.php");
    $membership = new Membership();
    $val = $_POST["email"];;
    $result = $membership->CheckEmailAddress(trim($val));
    echo json_encode($result); //output [e-mail]   
?>

Would now look like this:

<?PHP
    require_once("membership.php");
    $membership = new Membership();
    $val = $_POST["email"];;
    $result = $membership->CheckEmailAddress(trim($val));
    $result_value = !empty($result) ? 'true' : 'false';
    echo json_encode($result_value); //output [e-mail]   
?>

See that line that reads $result_value = !empty($result) ? 'true' : 'false';? That is an inline bit of code that is an alternative to if/else stuff for values. I have genuine forgotten the formal name for that method, but it is useful for cases like this. The log flow is basically

[value] = [test] ? [test value] : [default value];

That basically means if test passes, make the value what comes after the ?. If the test does not pass? then use the default value to the right of the :.