Question

我正在尝试在我的网站上设置登录系统。我们将在最终创建帐户，然后将详细信息发送给用户。

将所有相关的php文件上传到服务器时，login.php页面无法加载，并显示HTTP错误500。

login.php代码：

?php
// Include config file
require_once 'config.php';

// Define variables and initialize with empty values
$username = $password = "";
$username_err = $password_err = "";

// Processing form data when form is submitted
if($_SERVER["REQUEST_METHOD"] == "POST"){

    // Check if username is empty
    if(empty(trim($_POST["username"]))){
        $username_err = 'Please enter username.';
    } else{
        $username = trim($_POST["username"]);
    }

    // Check if password is empty
    if(empty(trim($_POST['password']))){
        $password_err = 'Please enter your password.';
    } else{
        $password = trim($_POST['password']);
    }

    // Validate credentials
    if(empty($username_err) && empty($password_err)){
        // Prepare a select statement
        $sql = "SELECT username, password FROM users WHERE username = ?";

        if($stmt = mysqli_prepare($link, $sql)){
            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "s", $param_username);

            // Set parameters
            $param_username = $username;

            // Attempt to execute the prepared statement
            if(mysqli_stmt_execute($stmt)){
                // Store result
                mysqli_stmt_store_result($stmt);

                // Check if username exists, if yes then verify password
                if(mysqli_stmt_num_rows($stmt) == 1){                    
                    // Bind result variables
                    mysqli_stmt_bind_result($stmt, $username, $hashed_password);
                    if(mysqli_stmt_fetch($stmt)){
                        if(password_verify($password, $hashed_password)){
                            // Password is correct, so start a new session and save the username to the session
                            session_start();
                            $_SESSION['username'] = $username;      
                            header("location: welcome.php");
                        } else{
                            // Display an error message if password is not valid
                            $password_err = 'The password you entered was not valid.';
                        }
                    }
                } else{
                    // Display an error message if username doesn't exist
                    $username_err = 'No account found with that username.';
                }
            } else{
                echo "Oops! Something went wrong. Please try again later.";
            }
        }

        // Close statement
        mysqli_stmt_close($stmt);
    }

    // Close connection
    mysqli_close($link);
}
?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Login</title>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.css" />
    <style type="text/css">
        body{ font: 14px sans-serif; }
        .wrapper{ width: 350px; padding: 20px; }
    </style>
</head>
<body>
    <div class="wrapper">
        <h2>Login</h2>
        <p>Please fill in your credentials to login.</p>
        <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
            <div class="form-group <?php echo (!empty($username_err)) ? 'has-error' : ''; ?>">
                <label>Username</label>
                <input type="text" name="username" class="form-control" value="<?php echo $username; ?>">
                <span class="help-block"><?php echo $username_err; ?></span>
            </div>    
            <div class="form-group <?php echo (!empty($password_err)) ? 'has-error' : ''; ?>">
                <label>Password</label>
                <input type="password" name="password" class="form-control">
                <span class="help-block"><?php echo $password_err; ?></span>
            </div>
            <div class="form-group">
                <input type="submit" class="btn btn-primary" value="Login">
            </div>
            <p>Don't have an account? <a href="register.php">Sign up now</a>.</p>
        </form>
    </div>    
</body>
</html>

浏览错误日志后，似乎错误位于第13和20行中，日志上的错误显示为“在写上下文中不能使用函数返回值”

任何人都可以帮忙吗？

Answer 1

问题是这个

<input id="username" type="text" 
       ng-attr-placeholder="{{localize && ('example_email' | localFilter) }}" />

因为空不是函数而是语言构造   ，并且只接受变量：

右：
!empty(trim($someText)) and doSomething()
错误：
empty($someVar)

如此处所述：

Weird PHP error: 'Can't use function return value in write context'

还值得一提的是，empty(someFunc())实际上是一种语言构造，而不是函数，不能使用变量函数（ 5.5版之前的版本）进行调用。

因此，在您的情况下，此empty()不起作用，您应该使用类似以下内容的文件：empty(trim($_POST['username']))。

有关更多信息，请参见文档： http://php.net/manual/en/function.empty.php

Login.php页面不会显示

1 个答案: