如何使用 PHP 函数正确验证我的注册表单输入？

Question

我是 PHP 的初学者，正在尝试验证我的注册表单，但 preg_match 函数和 email 过滤器 function 没有验证输入。 表单提交和值或插入到我的数据库中，任何输入都可以在未经验证的情况下工作。 这是我的 PHP：

<?php

// define errors
$firstnameErr = $lastnameErr = $usernameErr = $passwordErr = $emailaddressErr = "";




if ($_SERVER["REQUEST_METHOD"] == "POST") {


  if (empty($_POST["firstname"])) {
    $firstnameErr = "First Name is required";
  } else {
    $firstname = ($_POST["firstname"]);
    // name only contains letters and space
    if (!preg_match("/^[a-zA-Z ]*$/",$firstname)) {
      $firstnameErr = "Only letters and white space allowed";
    }
  }
    if (empty($_POST["lastname"])) {
    $lastnameErr = "Last Name is required";
  } else {
    $lastname= ($_POST["lastname"]);
    // name only contains letters and space
    if (!preg_match("/^[a-zA-Z ]*$/",$lastname)) {
      $lastnameErr = "Only letters and white space allowed";
    }
  }


 if (empty($_POST["emailaddress"])) {
    $emailaddressErr = "Email address is required";
  } else {
    $emailaddress = ($_POST["emailaddress"]);

    if (!filter_var($emailaddress, FILTER_VALIDATE_EMAIL)) {
      $emailaddressErr = "Invalid email format";
    }
  }


 if (empty($_POST["username"])) {
    $usernameErr = "A username is required";
  } else {
    $username = ($_POST["username"]);
  }



            if (empty($_POST["password"])) {
    $passwordErr = "A password is required";
  } else {

    $password = PASSWORD_HASH($_POST['password'], PASSWORD_DEFAULT);
        }

我的 HTML 在下面。 我想由于正则表达式，名字在客户端是经过验证的，但我希望它也可以在服务器端使用 preg_match 完成。 我不确定我这样做是否正确。

<form style="display:flex"; name="signupform" action="registration.php" method="post">


              <div class="container">
                <div class ="row justify-content-center">
                    <div class ="col-md-6">
                        <h1>Registration</h1>
                        <hr class="mb-3">

                        <label for="firstname"><b>First Name</b></label>
                        <input class= "form-control" type="text" placeholder="Enter your First Name" name="firstname" required>
                        <span class="error">* <?php echo $firstnameErr;?></span>

                        <label for="lastname"><b>Last Name</b></label>
                        <input class= "form-control" type="text" placeholder="Enter your Last Name" name="lastname" required>
                        <span class="error">* <?php echo $lastnameErr;?></span>

                        <label for="emailaddress"><b>Email Address</b></label>
                        <input class= "form-control" type="text" placeholder="Enter your Email Address" name="emailaddress" required>
                        <span class="error">* <?php echo $emailaddressErr;?></span>


                        <label for="username"><b>Username</b></label>
                        <input class= "form-control" type="text" placeholder="Enter your desired username" name="username" required>
                        <span class="error">* <?php echo $usernameErr;?></span>

                        <label for="password"><b>Password</b></label>
                        <input class= "form-control" type="password" placeholder="Enter a password" name="password" pattern="(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{8,}" title="Must contain at least one number and one uppercase and lowercase letter, and at least 8 or more characters" required>
                        <span class="error">* <?php echo $passwordErr;?></span>
                        <em> Password must contain at least one number and one uppercase and lowercase letter, and at least 8 or more characters</em><br>


                        <hr class ="mb-3">
                        <input class="btn btn-block btn-primary" type="submit" name="create" value="Sign Up">
                        <hr class = "mb-3">


                    </div>

                </div>
            </div>  
    </form>

Answer 1

在你的逻辑中尝试这样的事情。 因为您的变量（$lastname、$emailaddress）已在代码中声明并填充了未经测试的数据。

 if (empty($_POST["lastname"])) {
    $lastnameErr = "Last Name is required";
  } else {
    if (!preg_match("/^[a-zA-Z ]*$/",$_POST["lastname"])) {
      $lastnameErr = "Only letters and white space allowed";
    }else{
     /* if lastname valid then create $lastname */
     $lastname= $_POST["lastname"];
    }
  }
  if (empty($_POST["emailaddress"])) {
    $emailaddressErr = "Email address is required";
  } else {
    if (!filter_var($_POST["emailaddress"], FILTER_VALIDATE_EMAIL)) {
      $emailaddressErr = "Invalid email format";
    }else{
      // if email address valid then create $emailaddress
      $emailaddress = ($_POST["emailaddress"]);
    }
  }

因此，在调用 function 将数据存储在数据库中之前，只需检查变量是否存在isset($lastname) && isset($emailaddress) ...好吧我猜你明白了。

从我在网上看到的内容来看，你不应该相信来自前端的任何东西，即使有输入验证，在将数据插入数据库之前总是要仔细检查。

祝你好运。

Answer 2

我简化了你的代码，希望这会有所帮助:)

<?php
//define errors
$error_message = "";

$firstname="";
$lastname="";
$emailaddress="";
$username="";
$password="";

if(isset($_POST['create']) && $_SERVER["REQUEST_METHOD"] == "POST"){

$firstname = $_POST['firstname'];
$lastname = $_POST['lastname'];
$emailaddress = $_POST['emailaddress'];
$username = $_POST['username'];
$password = password_hash($_POST['password'], PASSWORD_DEFAULT);


if(empty($firstname) || $firstname == ""){
$error_message = "First Name is required!";
}
elseif( !preg_match("/^[a-zA-Z ]*$/",$firstname) ){
$error_message = "Only letters and white space allowed!";
}
elseif(empty($lastname) || $lastname == ""){
$error_message = "Last Name is required!";
}
elseif( !preg_match("/^[a-zA-Z ]*$/",$lastname) ){
$error_message = "Only letters and white space allowed!";
}
elseif(empty($emailaddress) || $emailaddress == ""){
$error_message = "Email address is required!";
}
elseif(!filter_var($emailaddress, FILTER_VALIDATE_EMAIL)){
$error_message = "Invalid email format!";
}
elseif(empty($username) || $username == ""){
$error_message = "Username is required!";
}
elseif(empty($password) || $password == ""){
$error_message = "Password is required!";   
}
else{
//insert query
}

}

?>

<!DOCTYPE html>
<html>
<head>
<title></title>
</head>
<body>
<form style="display:flex"; name="signupform" action="" method="post">


          <div class="container">
            <div class ="row justify-content-center">
                <div class ="col-md-6">
                    <span class="error">* <?php echo $error_message;?></span>
                    <h1>Registration</h1>
                    <hr class="mb-3">

                    <label for="firstname"><b>First Name</b></label><br>
                    <input class= "form-control" type="text" placeholder="Enter your First Name" name="firstname" value="<?php echo $firstname; ?>"><br>


                    <label for="lastname"><b>Last Name</b></label><br>
                    <input class= "form-control" type="text" placeholder="Enter your Last Name" name="lastname" value="<?php echo $lastname; ?>"><br>


                    <label for="emailaddress"><b>Email Address</b></label><br>
                    <input class= "form-control" type="text" placeholder="Enter your Email Address" name="emailaddress" value="<?php echo $emailaddress; ?>"><br>


                    <label for="username"><b>Username</b></label><br>
                    <input class= "form-control" type="text" placeholder="Enter your desired username" name="username" value="<?php echo $username; ?>"><br>


                    <label for="password"><b>Password</b></label><br>
                    <input class= "form-control" type="password" placeholder="Enter a password" name="password" pattern="(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{8,}" title="Must contain at least one number and one uppercase and lowercase letter, and at least 8 or more characters" value="<?php echo $password; ?>"><br>

                    <em> Password must contain at least one number and one uppercase and lowercase letter, and at least 8 or more characters</em><br>


                    <hr class ="mb-3">
                    <input class="btn btn-block btn-primary" type="submit" name="create" value="Sign Up" style="cursor: pointer;">

</body>
</html>