由于 if 语句，PHP 表单无法验证或发送？

Question

我正在尝试通过让用户填写已验证的表单来更新页面上的表格。由于某种原因，当我添加验证 if 语句时，除了当用户单击“添加新”时刷新之外，表单不会执行任何操作。如果我删除 if 语句，表就会更新。我缺少什么？

<?php
session_start();
require_once "db.php";

if ( isset ($_POST['url']) && isset ($_POST['email']) 
&& isset ($_POST['length']) && isset ($_POST['rating']) ) {

    //Reject empty form fields
    if (strlen($_POST['url']) < 1 || strlen($_POST['email']) <1 || strlen ($_POST['length']) <1 || strlen($_POST['rating']) < 1) {
    $_SESSION['error'] = 'All values are required';
    header('Location: add.php');
    return;
    } 

    //Reject urls that are not http or https
    $url = $_POST['url'];
    if (strpos($url,"http://") !== 0 && strpos($url, "https://") !== 0 ) {
    $_SESSION['error'] = 'Error in input data';
    header('Location: add.php');
    return;
    }

    //Reject emails without '@' symbol
    if ( strpos($_POST['email'], "@") === false ) {
    $_SESSION['error'] = 'Error in input data';
    header('Location: add.php');
    return;
    }

    //Reject track lengths or rating numbers that are too small
    if ( $_POST['length'] +0 < 1 || $_POST['rating'] +0 < 1 ) {
    $_SESSION['error'] = 'Error in input data';
    header('Location: add.php');
    return;
    }

    $sql = "INSERT INTO videos (url, email, length, rating) 
              VALUES (:url, :email, :length, :rating)";
    $stmt = $pdo->prepare($sql);
    $stmt->execute(array(
            ':url' => $_POST ['url'],
            ':email' => $_POST ['email'],        
            ':length' => $_POST['length'],
            ':rating' => $_POST['rating']));
   $_SESSION['success'] = 'Record Added';
   header( 'Location: index.php' ) ;
   return;

}

?>

<p>Add A New Video</p>
<form method="post">
<p>URL:
<input type="text" name="url"></p>
<p>Email:
<input type="text" name="email"></p>
<p>Length:
<input type="text" name="length"></p>
<p>Rating:
<input type="text" name="rating"></p>
<p><input type="submit" value="Add New"/>
<a href="index.php">Cancel</a></p>
</form>

Answer 1

我想说，使用 strpos 进行验证很容易出现问题。尝试使用这样的正则表达式:

if (! preg_match('/[^@\s]{3,}@([-a-z0-9]{2,}\.)+[a-z]{2,}/', $_POST['e_mail'])) { $_SESSION['error'] = 'Error in input data'; }