Question

如果有人能够弄明白这一点，那会非常有帮助。所以我试图在登录表单的同一页面上显示错误。我认为问题是表单操作，因为总是加载该页面。我添加了空条件和变量但不确定如何将它们添加到HTML中。

错误消息已添加为php代码
目前，表单操作是问题（我认为）其加载checklogin.php并带有空白页
如何在同一页面上显示表单下方显示的错误消息？

...谢谢

HTML：

<head>
<meta charset="UTF-8">
    <title>Entry form login</title>     

</head>

<body>


    <div class= "wrap">
      <img src="/images/logo.png" alt="Highdown logo" />
      <h1>Sports day</h1> 
    </div>


    <div class='container'>     
        <div class='form'>
            <form id ="form" action ="checklogin.php" method="post">                                                
                <label for = "user">Username:</label> 
                <input type ="text" name ="username"><br>

                <label for ="password">Password:</label>    
                <input type ="password" name ="password"><br> <span class="error"> <?php echo $error;?></span>  



                <input type ="submit" name ="loginbutton" id ="loginbutton" value ="Log in">    
            </form>
        </div>
    </div>  


    <link rel="stylesheet" type="text/css" href="styles.css">
</body>

php：

<?php
    session_start();
    require_once 'db/connect.php';
    $error='';

    if (isset($_POST['loginbutton'])){

        if (empty($_POST['username']) && empty($_POST['password'])) { 
            $error = 'Please enter your username and password';
        }   


        else {
            // Username and password sent from the form
            $username = $_POST['username'];
            $password = $_POST['password'];

            // Protect MySQL injection
            $username= stripslashes($username);
            $password = stripslashes($password);
            $username = mysqli_real_escape_string($con, $username);
            $password = mysqli_real_escape_string($con, $password);
            $encryptpass = md5($password); // Use md5 to encrypt password 

            $sql = "SELECT * FROM teacher WHERE Username = '$username' and Password = '$encryptpass'"; 

            $result=mysqli_query($con, $sql);

            // my_sql_num row is counting table row
            $count = mysqli_num_rows($result);

            //If result matched $username and $password, table row must be 1 row
            if ($count==1) {        
                $_SESSION['Username']=$username;
                header("location:homepage.php");
            }

            else {
                $error = 'Username and/or password is invalid';
            }
        }
    }   
?>

Answer 1

您可以组合它们并从表单元素中删除action属性。

<?php
    session_start();
    require_once 'db/connect.php';
?>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
    <title>Entry form login</title>     
    <link rel="stylesheet" type="text/css" href="styles.css">
</head>

<body>


    <div class= "wrap">
      <img src="/images/logo.png" alt="Highdown logo" />
      <h1>Sports day</h1> 
    </div>


    <div class='container'>     
        <div class='form'>
            <form id ="form" method="post">                                                
                <label for = "user">Username:</label> 
                <input type ="text" name ="username"><br>

                <label for ="password">Password:</label>    
                <input type ="password" name ="password"><br> <span class="error"> <?php echo $error;?></span>  



                <input type ="submit" name ="loginbutton" id ="loginbutton" value ="Log in">    
            </form>
<?php
    $error='';

    if (isset($_POST['loginbutton'])){

        if (empty($_POST['username']) && empty($_POST['password'])) { 
            $error = 'Please enter your username and password';
        }   


        else {
            // Username and password sent from the form
            $username = $_POST['username'];
            $password = $_POST['password'];

            // Protect MySQL injection
            $username= stripslashes($username);
            $password = stripslashes($password);
            $username = mysqli_real_escape_string($con, $username);
            $password = mysqli_real_escape_string($con, $password);
            $encryptpass = md5($password); // Use md5 to encrypt password 

            $sql = "SELECT * FROM teacher WHERE Username = '$username' and Password = '$encryptpass'"; 

            $result=mysqli_query($con, $sql);

            // my_sql_num row is counting table row
            $count = mysqli_num_rows($result);

            //If result matched $username and $password, table row must be 1 row
            if ($count==1) {        
                $_SESSION['Username']=$username;
                header("location:homepage.php");
            }

            else {
                $error = 'Username and/or password is invalid';
            }
        }
    }   
?>
        </div>
    </div>  


</body>
</html>

Answer 2

另一种方法是让表单操作指向同一个脚本，如下所示：

 action="<?php echo $_SERVER['PHP_SELF'] ?>"

在同一页面上显示错误

2 个答案: