Stop and validate empty fields - php

cobusbo · January 20, 2015

Hi I'm currently having a problem with my form. Users submit an empty field into the database and the next time another user tries to enter it just says username has been taken. I need some help on how to confirm that the username and email field isnt empty when inserted and that the email address is in the correct format.

<?php include "base.php"; ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">  
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />  
 
<title>User Management System (Tom Cameron for NetTuts)</title>
<link rel="stylesheet" href="style.css" type="text/css" />
</head>  
<body>  
<div id="main">
<?php
     $username = mysql_real_escape_string($_POST["username"]);
$email = mysql_real_escape_string($_POST["email"]);








$mxitid = mysql_real_escape_string($_SERVER["HTTP_X_MXIT_USERID_R"]);
if(!isset($mxitid))
{
	$mxitid = "DEFAULT";
}

     $checkusername = mysql_query("SELECT * FROM Users WHERE mxitid = '".$mxitid."'");
      $checkemail = mysql_query("SELECT * FROM Users WHERE email = '".$email."'");

     if(mysql_num_rows($checkusername) == 1)
     {
        echo "<h1>Error</h1>";
        echo "<p>Sorry, that username is taken. Please go <a href=\"register.php\">back</a>and try again.</p>";
     }
elseif(mysql_num_rows($checkemail) == 1)
     {
        echo "<h1>Error</h1>";
        echo "<p>Sorry, that email is taken. Please go <a href=\"register.php\">back</a>and try again.</p>";
     }

     elseif ($_POST["register"]) 
     {
$username = mysql_real_escape_string($_POST["username"]);
if(!isset($mxitid))

$mxitid = mysql_real_escape_string($_SERVER["HTTP_X_MXIT_USERID_R"]);
if(!isset($mxitid))
{
	$mxitid = "DEFAULT";
}

        $registerquery = mysql_query("INSERT INTO Users (Username,mxitid,email) VALUES('".$username."','".$mxitid."','".$email."')");
        if($registerquery)
        {
            echo "<h1>Success</h1>";
            echo "<p>Your account was successfully created. Please <a href=\"index9.php\">click here to start chatting</a>.</p>";
        }
     }

else
{
    ?>
     
   <h1>Register</h1>
     
   <p>Please enter your details below to register.</p>
<p>Keep it clean! or you might get banned!</p>

     
    <form method="post" action="register.php" name="registerform" id="registerform">
    <fieldset>
        <label for="username">Username:<br>
Using emoticons in your name won't work!</label><input type="text" name="username" id="username" /><br />
<label for="email">Email:<br>(We need your real one to be able to contact you!)<br>
 If you don't have one make use of your mxit email service.</label><input type="email" name="email" id="email" /><br />

        <input type="hidden" name="mxitid" id="mxitid" value="<? $_SERVER['HTTP_X_MXIT_USERID_R']; ?>"/><br />
        <input type="submit" name="register" id="register" value="Register" />
    </fieldset>
    </form>
     
    <?php
}
?>
 
</div>
</body>
</html>

I tried using

function check_input($data, $problem='')
{
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    if ($problem && strlen($data) == 0)
    {
        die($problem);
    }
    return $data;
}

but it didnt seems to work

cyberRobot · January 20, 2015

Before anything gets added to the database, you could check if the username (or email) is empty by doing something like this:

<?php
if($username != '') {
    //continue processing form
} else {
    //let user know that $username can't be blank
}

Of course, you'll want to adapt the code so that it checks all the necessary form fields before the script saves anything to the database.

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Stop and validate empty fields - php

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