我不知道我的代码做错了什么，php表单验证的错误消息停止工作。
它一直工作得很好，直到我在输入中添加了value属性，这样即使页面刷新并且由于typeError而没有交付，用户输入也会持续存在。
表单不再显示任何错误，但我添加value属性的原因是有效的。
我正在学习php，请帮助我理解为什么我有这个问题。我不明白，因为我没有从php中得到任何错误。
这是我的代码
<?php
// empting the value variables when user have'nt typed anything to prevent error. This is the shorthand of typing samething that's going to have the same value
$email = $title = $ingredients = '';
// put out the error on the html instead of echoing it
// so i used array so that i can neatly put out all the errors instead of using different variables for all
$error = array('email' => '', 'title' => '', 'ingredients' => '');
// check if the form was clicked and retrive the values sent
// i will achieve this by using a default method called isset() and i will check if value is contained in the form using the submit btn, this is because when a user clicks on the form submit, the user have entered a value
if(isset($_POST['submit'])){
// check if the field submited is empty
// we achieve this using a default method called empty()
// we check them one field at a time
// check for email
if(empty($_POST['email'])){
$error['email'] = ' Email is empty';
} else {
$email = $_POST['email'];
}
// check for title
if(empty($_POST['title'])){
$error['title'] = ' Title is empty';
} else {
$title = $_POST['title'];
}
// check for ingredients
if(empty($_POST['ingredients'])){
$error['ingredients'] = ' Ingredients is empty';
} else {
$ingredients = $_POST['ingredients'];
}
}
?>
<!DOCTYPE html>
<html lang="en">
<?php include 'template/header.php'?>
<form action="form.php" method="POST">
<div class="input_div">
<label >Email :</label>
<input type="text" name="email" value=" <?php echo $email ?> ">
<div class="error_msg"><?php echo $error['email']; ?></div>
</div>
<div class="input_div" >
<label >Pizza Title :</label>
<input type="text" name="title" value=" <?php echo $title ?> " >
<div class="error_msg"><?php echo $error['title']; ?></div>
</div>
<div class="input_div" >
<label >Ingredients (comma seperated) :</label>
<input type="text" name="ingredients" value=" <?php echo $ingredients ?> ">
<div class="error_msg"><?php echo $error['ingredients']; ?></div>
</div>
<div class="input_div" >
<input type="submit" class="submitBtn" name="submit" value="Submit">
</div>
</form>
<?php include 'template/footer.php' ?>
</html>
除了输入中的空白问题之外，当将值插入回表单时，您还应该注意XSS(比如使用"会破坏表单(，并且在需要之前不要填充错误，这将允许您轻松地继续执行成功步骤，而无需在$errors数组上循环，还允许您隐藏<div class="error_msg"></div>元素，只在出现错误时显示。
还有您丢失的<head>和<body>，假设它们在include中，但这样做会使添加其他元素或脚本变得相当困难。
<?php
$email = $title = $ingredients = '';
$error = [];
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
// check for email
if (empty($_POST['email'])) {
$error['email'] = 'Email is empty';
} else {
$email = $_POST['email'];
}
// check for title
if (empty($_POST['title'])) {
$error['title'] = 'Title is empty';
} else {
$title = $_POST['title'];
}
// check for ingredients
if (empty($_POST['ingredients'])) {
$error['ingredients'] = 'Ingredients is empty';
} else {
$ingredients = $_POST['ingredients'];
}
if (empty($error)) {
// do some thing with $email, $title, $ingredients
die(header('Location: ./thank-you.php'));
}
}
function xss_safe($value) {
return htmlspecialchars($value, ENT_QUOTES, 'UTF-8');
}
?><!DOCTYPE html>
<html lang="en">
<?php include 'template/header.php' ?>
<form action="form.php" method="POST">
<div class="input_div">
<label>Email :</label>
<input type="text" name="email" value="<?= xss_safe($email) ?>"/>
<?= isset($error['email']) ? '<div class="error_msg">'.$error['email'].'</div>' : '' ?>
</div>
<div class="input_div">
<label>Pizza Title :</label>
<input type="text" name="title" value="<?= xss_safe($title) ?>"/>
<?= isset($error['title']) ? '<div class="error_msg">'.$error['title'].'</div>' : '' ?>
</div>
<div class="input_div">
<label>Ingredients (comma seperated) :</label>
<input type="text" name="ingredients" value="<?= xss_safe($ingredients) ?>"/>
<?= isset($error['ingredients']) ? '<div class="error_msg">'.$error['ingredients'].'</div>' : '' ?>
</div>
<div class="input_div">
<input type="submit" class="submitBtn" name="submit" value="Submit">
</div>
</form>
<?php include 'template/footer.php' ?>
</html>
由于您的错误检查只是针对空/遗漏的输入字段，因此更容易根据HTML5进行所需的输入。这是一个简化的版本，在表单提交后使用占位符作为信息。
警告：如果要将这些数据插入MySQL表，则需要首先对输入进行消毒！
<?php
$email = $title = $ingredients = "";
if (isset($_POST["submit"])) {
$email = $_POST["email"];
$title = $_POST["title"];
$ingredients = $_POST["ingredients"];
}
echo "
<form method='POST'>
<label>Email:</label>
<input type='email' name='email' placeholder='$email' required>
<label>Pizza Title:</label>
<input type='text' name='title' placeholder='$title' required>
<label>Ingredients (comma seperated):</label>
<input type='text' name='ingredients' placeholder='$ingredients' required>
<input type='submit' name='submit' value='Submit'>
</form>
";
?>