我使用来自W3 (http://www.w3schools.com/php/php_form_complete.asp)的代码为给定的示例表单进行服务器端验证。
<!DOCTYPE HTML>
<html>
<head>
<style>
.error {color: #FF0000;}
</style>
</head>
<body>
<?php
// define variables and set to empty values
$nameErr = $emailErr = $genderErr = $websiteErr = "";
$name = $email = $gender = $comment = $website = "";
if ($_SERVER["REQUEST_METHOD"] == "POST") {
if (empty($_POST["name"])) {
$nameErr = "Name is required";
} else {
$name = test_input($_POST["name"]);
// check if name only contains letters and whitespace
if (!preg_match("/^[a-zA-Z ]*$/",$name)) {
$nameErr = "Only letters and white space allowed";
}
}
if (empty($_POST["email"])) {
$emailErr = "Email is required";
} else {
$email = test_input($_POST["email"]);
// check if e-mail address syntax is valid
if (!preg_match("/(['w'-]+'@['w'-]+'.['w'-]+)/",$email)) {
$emailErr = "Invalid email format";
}
}
if (empty($_POST["website"])) {
$website = "";
} else {
$website = test_input($_POST["website"]);
// check if URL address syntax is valid (this regular expression also allows dashes in the URL)
if (!preg_match("/'b(?:(?:https?|ftp):'/'/|www'.)[-a-z0-9+&@#'/%?=~_|!:,.;]*[-a-z0-9+&@#'/%=~_|]/i",$website)) {
$websiteErr = "Invalid URL";
}
}
if (empty($_POST["comment"])) {
$comment = "";
} else {
$comment = test_input($_POST["comment"]);
}
if (empty($_POST["gender"])) {
$genderErr = "Gender is required";
} else {
$gender = test_input($_POST["gender"]);
}
}
function test_input($data) {
$data = trim($data);
$data = stripslashes($data);
$data = htmlspecialchars($data);
return $data;
}
?>
<h2>PHP Form Validation Example</h2>
<p><span class="error">* required field.</span></p>
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
Name: <input type="text" name="name" value="<?php echo $name;?>">
<span class="error">* <?php echo $nameErr;?></span>
<br><br>
E-mail: <input type="text" name="email" value="<?php echo $email;?>">
<span class="error">* <?php echo $emailErr;?></span>
<br><br>
Website: <input type="text" name="website" value="<?php echo $website;?>">
<span class="error"><?php echo $websiteErr;?></span>
<br><br>
Comment: <textarea name="comment" rows="5" cols="40"><?php echo $comment;?></textarea>
<br><br>
Gender:
<input type="radio" name="gender" <?php if (isset($gender) && $gender=="female") echo "checked";?> value="female">Female
<input type="radio" name="gender" <?php if (isset($gender) && $gender=="male") echo "checked";?> value="male">Male
<span class="error">* <?php echo $genderErr;?></span>
<br><br>
<input type="submit" name="submit" value="Submit">
</form>
<?php
echo "<h2>Your Input:</h2>";
echo $name;
echo "<br>";
echo $email;
echo "<br>";
echo $website;
echo "<br>";
echo $comment;
echo "<br>";
echo $gender;
?>
</body>
</html>
虽然服务器端验证工作得很好，但我不能让mail()函数只有在$name(作为主题)和$comment(作为消息)字段都被填充时才能工作。我试过很多组合，但是电子邮件总是提交，即使字段是空的。
所以我的问题是:如何使这个验证表单发送电子邮件只有当$name和$comment字段填充和验证?
当名称无效时创建$nameErr，当注释有效时创建$comment为空字符串，您可以使用以下条件:
if (!$nameErr && $comment) {
}
空字符串被认为是FALSE:http://php.net/manual/en/language.types.boolean.php
你总是可以使用标志。
<?php
....
// let's say there are some flags for validation
if($flag1 && $flag2 && .. $flagN){
// perform email sending here
}
?>
或者您可以使用默认的错误消息变量;检查它们是否为空
<?php
if(!empty($nameErr) && !empty($comment)){
// perform email sending
}
?>
在验证了$name和$comment之后执行验证:
if($nameErr == "" && $emailErr == "") { // If they are empty, no errors where found
// Do your email validation here
}