Question

登录成功后，用户将被重定向到我网站的主页面。我的代码在输入错误的登录详细信息（login_parse.php）时将用户重定向到空白页面，此处出现错误消息“登录失败”。我希望错误消息出现在登录页面上（index.php）。

登录页面：

<?php session_start(); ?>
<!DOCTYPE html> 
<html>

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

<head>
</head>

<body>


<form id='registration_form' action='registration.php' method='post'>
    <input id ='new_username' type='text' name='new_username'     placeholder='Create a username' oninvalid="this.setCustomValidity('Please create   a username')"required></input>
    <input id ='new_password' type='password' name='new_password'     placeholder='Create a password' oninvalid="this.setCustomValidity('Please create     a password')" required></input>
    <input id ='new_email' type='email' name='new_email' placeholder='Enter   a   valid student.lboro.ac.uk email     address'oninvalid="this.setCustomValidity('Please enter a valid     student.lboro.ac.uk email address')" required></input>
    <input id ='register_button' type='submit' value='Sign Up'/>
</form>

</body>
</html>

login_parse.php：

<?php

session_start();

include "dbconnect.php";

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

  $username = $_POST['username'];
  $password = $_POST['password'];
  $sql = "SELECT * FROM Users WHERE username= '".$username."' AND   password='".$password."' LIMIT 1";
  $res = mysqli_query($db, $sql) or die(mysqli_error);

       if (mysqli_num_rows($res) == 1) {

          $row = mysqli_fetch_array($res);
          $_SESSION['uid'] = $row['id'];
          $_SESSION['username'] = $row['username'];
          header("Location: shownewposts.php");
          exit();


          } 
          else {

            echo "Login unsuccessful";
            exit();
          }

}

?>

Answer 1

查看http://www.phptherightway.com/#pdo_extension输入过滤器和PDO。

您可以在else语句中创建会话变量。喜欢的东西：

<?php

session_start();

include "dbconnect.php";

if (isset($_POST['username'])) {
  unset( $_SESSION['errorMessage'] );
  $username = $_POST['username'];
  $password = $_POST['password'];
  $sql = "SELECT * FROM Users WHERE username= '".$username."' AND   password='".$password."' LIMIT 1";
  $res = mysqli_query($db, $sql) or die(mysqli_error);

   if (mysqli_num_rows($res) == 1) {

      $row = mysqli_fetch_array($res);
      $_SESSION['uid'] = $row['id'];
      $_SESSION['username'] = $row['username'];
      header("Location: shownewposts.php");
      exit();


  } 
  else {
      $_SESSION['errorMessage'] = 1;
      header("Location: index.php");
      exit();
  }

}

?>

在index.php中检查会话变量是否存在并打印消息

<?php session_start(); ?>
<!DOCTYPE html> 
<html>

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

<head>
</head>

<body>

<?php
   if (isset($_SESSION['errorMessage']){
     echo "<span style='color:red;'>Check your input</span>";
   }
?>
<form id='registration_form' action='registration.php' method='post'>
    <input id ='new_username' type='text' name='new_username'     placeholder='Create a username' oninvalid="this.setCustomValidity('Please create   a username')"required></input>
    <input id ='new_password' type='password' name='new_password'     placeholder='Create a password' oninvalid="this.setCustomValidity('Please create     a password')" required></input>
    <input id ='new_email' type='email' name='new_email' placeholder='Enter   a   valid student.lboro.ac.uk email     address'oninvalid="this.setCustomValidity('Please enter a valid     student.lboro.ac.uk email address')" required></input>
    <input id ='register_button' type='submit' value='Sign Up'/>
</form>

</body>
</html>

如何使用php在登录页面上显示登录错误消息

1 个答案: