PHP当表单空白时发布值

Question

我有一个php表单，用于更改没有必填字段的用户数据。 我想检查用户是否在表单的字段中输入数据。

我最初的想法是，如果用户点击提交留下了一些 字段为空，那么POST方法将在 $ _POST ['field']变量中输入NULL值。

因此，我检查了是否使用'isset'函数设置了$ POST ['field']变量。不幸的是，看起来，POST方法不会在表单中未指定的变量中输入NULL值。这使得if（isset（$ [POST]）语句成为真实的，因为POST方法确实为这些变量设置了一些值。

有关如何检查用户是否在字段中输入数据的任何想法？ 这里是我的代码：

<?php 
include 'core/init.php'; 
//logged_in_redirect(); 
include 'includes/overall/admin_start.php'; 
?> 

<h2>Employee information: </h2> 
<?php 
echo "Username: ", $_SESSION['user_data']['username'], "<br>"; 
echo "First name: ", $_SESSION['user_data']['first_name'], "<br>"; 
echo "Last name: ", $_SESSION['user_data']['last_name'], "<br>"; 
echo "Email: ", $_SESSION['user_data']['email'], "<br>"; 
echo "City: ", $_SESSION['user_data']['city'], "<br>"; 
echo "Type: ", $_SESSION['user_data']['type'], "<br>"; 

?> 

<h2> Alter information: </h2> 

<?php 

if(empty($_POST) === true){ 
    echo "print"; 
} 
else{ 
    if(isset($_POST['username'])){ 
     if(user_exists($_POST['username']) === true){ 
      $errors[] = 'Sorry, the username \'' . $_POST['username'] . '\' 
is already taken.'; 
     } 
     if(preg_match("/\\s/", $_POST['username']) == true){ 
      $errors[] = 'Your username must not contain any spaces.'; 
     } 
     if(strlen($_POST['username']) > 30){ 
      $errors[] = 'The size of one of your entries is not acceptable. 
Entry size must be smaller than 30 characters.'; 
     } 
    } 
    if(isset($_POST['password'])){ 
     //echo $_POST['password']; 
     if(strlen($_POST['password']) < 6){ 
      $errors[] = 'Your password size is not acceptable. Password size 
must be between 6 and 30 characters.'; 
     } 
     if($_POST['password'] !== $_POST['repeat_pass']){ 
      $errors[] = 'Your password entries do not match.'; 
     } 
     if(strlen($_POST['password']) > 30){ 
      $errors[] = 'The size of one of your entries is not acceptable. 
Entry size must be smaller than 30 characters.'; 
     } 
    } 
    if(isset($_POST['email'])){ 
     if(filter_var($_POST['email'], FILTER_VALIDATE_EMAIL) === false){ 
      $errors[] = 'A valid email address is required.'; 
     } 
     if(email_exists($_POST['email']) === true){ 
      $errors[] = 'Sorry, the email \'' . $_POST['email'] . '\' is 
already in use.'; 
     } 
     if(strlen($_POST['email']) > 30){ 
      $errors[] = 'The size of one of your entries is not acceptable. 
Entry size must be smaller than 30 characters.'; 
     } 
    } 
    if(isset($_POST['type'])){ 
     if(($_POST['type'] !== "1") && ($_POST['type'] !== "2") && 
($_POST['type'] !== "3")){ 
      $errors[] = 'Please insert a correct number in the field type'; 
     } 
    } 
    if(isset($_POST['city'])){ 
     if(city_exists($_POST['city']) === false){ 
      $errors[] = 'Sorry, there is no shop in the specified city'; 
     } 
     if(strlen($_POST['city']) > 30){ 
      $errors[] = 'The size of one of your entries is not acceptable. 
Entry size must be smaller than 30 characters.'; 
     } 
    } 
} 
?> 

<?php 
if(isset($_GET['success']) && empty($_GET['success'])){ 
    echo 'You have altered the employee successfully'; 
} 
else 
{ 
    if(empty($_POST) === false && empty($errors) === true) 
    { 
     if(isset($_POST['username'])){$register_data['username'] = 
$_POST['username'];} 
     if(isset($_POST['password'])){$register_data['password'] = 
$_POST['password'];} 
     if(isset($_POST['first_name'])){$register_data['first_name'] = 
$_POST['first_name'];} 
     if(isset($_POST['last_name'])){$register_data['last_name'] = 
$_POST['last_name'];} 
     if(isset($_POST['email'])){$register_data['email'] = 
$_POST['email'];} 
     if(isset($_POST['city'])){$register_data['city'] = $_POST['city'];} 
     if(isset($_POST['type'])){$register_data['type'] = $_POST['type'];} 


     alter_user($register_data); 
     header('Location: alter_employee.php?success'); 
    } 
    else{echo output_errors($errors);} 
?> 

<form action="" method="post"> 
    <ul> 

     <li> 
      Username:<br> 
      <input type="text" name="username"> 
     </li> 
     <p><li> 
      Password:<br> 
      <input type="password" name="password"> 
     </li></p> 
     <p><li> 
      Repeat password*:<br> 
      <input type="password" name="repeat_pass"> 
     </li></p> 
     <p><li> 
      First name:<br> 
      <input type="text" name="first_name"> 
     </li></p> 
     <p><li> 
      Last name:<br> 
      <input type="text" name="last_name"> 
     </li></p> 
     <p><li> 
      Email:<br> 
      <input type="text" name="email"> 
     </li></p> 
     <p><li> 
      City:<br> 
      <input type="text" name="city"> 
     </li></p> 
     <p><li> 
      Type (1,2,3):<br> 
      <input type="text" name="type"> 
     </li></p> 
     <p><li> 
      <input type="submit" value="Register"> 
     </li></p> 

    </ul> 

</form> 

<?php 
} 
include 'includes/overall/end.php'; ?> 

Answer 1

避免使用empty，因为它还会检查像0和"0"这样的伪造条件，并且只有使用isset才会捕获空字符串。最好检查空输入的预期值，例如

if (isset($_POST['fieldName']) && trim($_POST['fieldName']) !== "") { 
    echo "There's something here!"; 
} 

Answer 2

例如，你可以这样做：

$foo = (!isset($_POST['foo']) || empty($_POST['foo'])) ? 'default value' : $_POST['foo']; 

您检查，看看它是不是与发布设置，并提供一个默认值，否则填充变量值。