页面加载时会自动调用PHP函数，而不是通过onclick事件调用
[英]PHP function is automatically called when page loads, instead of being called through onclick event
问题描述
I'm trying to redirect users of a web page to one of two different pages, depending on which of two buttons they click. 
我试图将网页的用户重定向到两个不同的页面之一，具体取决于他们单击的是两个按钮中的哪个。 My approach was to link each onclick event to a javascript function, which would in turn call a php function which uses the header() function to redirect to the appropriate page. 我的方法是将每个onclick事件链接到javascript函数，该函数随后将调用php函数，该函数使用header（）函数重定向到相应的页面。 Unfortunately, the latter of the two php functions, namely insertIntoTable(), is being called automatically each time the page loads and redirecting, without giving the user a chance to even look at the page with the buttons. 不幸的是，每次页面加载和重定向时，都会自动调用两个php函数中的后者，即insertIntoTable（），而没有给用户提供甚至使用按钮查看页面的机会。 I'm wondering if this is an artifact of way PHP is expanded? 我想知道这是否是PHP扩展方式的产物？ I don't really understand, becauseit seems like the wrapping javascript function shouldn't be called until the onclick event listener does so, and the php functions shouldn't be called until on the the javascript functions linked to onclick do so. 我不太了解，因为似乎只有在onclick事件监听器调用包装的javascript函数之前，才应该调用包装的javascript函数，而在链接到onclick的javascript函数上才应该调用php函数。 Here is the code... 这是代码...
<?php
session_start();
?>
<html>
<head>
<script>
function createATable()
{
<?php createATable(); ?>
}
function insertIntoTable()
{
<?php insertIntoTable(); ?>
}
</script>
</head>
<body>
<?php
// Define our redirection functions for button click events
function createATable()
{
header("Location: http://codd.edu/Project2/createtable.php?<?php echo htmlspecialchars(SID); ?>");*/
}
function insertIntoTable()
{
header("Location: http://codd.edu/Project2/insertintotable.php?<?php echo htmlspecialchars(SID); ?>");*/
}
// Set session variables so that we don't need to worry about whether
// we're coming from sign in or registration - if $Session['user_name']
// isn't set, we know were coming from the sign in
if (!$_SESSION['user_name'])
{
$_SESSION['user_name'] = $_POST['nametextbox'];
$_SESSION['user_psswd'] = $_POST['psswdtextbox'];
echo "<br />setting session variables";
}
echo "<br />Not setting session variables";
// If we aren't setting the session variables, then we are coming from the
// registration page, and therefore know that this isn't an admin account
$_SESSION['is_admin'] = "false";
// Connect to database
$conn = mysql_connect("localhost", "601", "23");
or die('Could not connect: ' . mysql_error());
// Open database
mysql_select_db("601", $conn)
or die('Could not find database: ' . mysql_error());
// Get USER tuples, if any
$user = mysql_query("SELECT * FROM USERS WHERE name='$_SESSION[user_name]' AND password='$_SESSION[user_psswd]'");
// If there are no entries for this SELECT command, we cannot
// allow the user to log in
$num_user = mysql_num_rows($user);
if ($num_user < 1)
{
$_SESSION['is_user'] = "false";
header("Location: http://codd.edu/Project2/login.php?<?php echo htmlspecialchars(SID); ?>");
exit;
}
else
{
$_SESSION['user_id'] = SID;
$_SESSION['is_user'] = "true";
echo "Welcome ", $_SESSION['user_name'], "!";
echo "<br />User ID: " . $_SESSION['user_id'];
echo "<br /> User Password: " . $_SESSION['user_psswd'];
echo "Is valid user? " . $_SESSION['is_user'];
session_destroy();
echo "<button name='createtable' onclick='createATable()'>Create a Table</button>";
echo "<br /><button name='insert' onclick='insertIntoTable()'>Insert into Table</button>";
}
?>
</body>
</html>
2 个解决方案
解决方案1
3 已采纳 2012-10-27 23:06:48
I see no reason why createATable() shouldn't be called anytime the page is loaded. 我认为没有理由为什么在页面加载时不应该调用createATable() 。 PHP is evaluated before javascript and on a different environment. PHP在使用JavaScript之前和在其他环境中进行评估。 Moreover, PHP allows you do define/declare a function after you call it, that is exactly what you're doing. 而且，PHP允许您在调用函数后定义/声明一个函数，这正是您正在做的事情。
Pretend to be the PHP interpreter: it has no idea of what javascript is. 伪装成PHP解释器：它不知道什么是javascript。 You can even wrap the <?php createATable(); ?> 您甚至可以包装<?php createATable(); ?> <?php createATable(); ?> line with yadayadayada ... qweryasdasd before and after it, and it will run. <?php createATable(); ?>前后都有yadayadayada ... qweryasdasd行，它将运行。
Please, read this and see if it helps: http://www.developer.com/tech/article.php/923111/Client-side-Versus-Server-side-Coding---Part-1.htm 请阅读此内容，看看是否有帮助： http : //www.developer.com/tech/article.php/923111/Client-side-Versus-Server-side-Coding---Part-1.htm
PS.: this is not related to your question, but please take a look at this: http://en.wikipedia.org/wiki/SQL_injection PS .：这与您的问题无关，但是请看一下： http : //en.wikipedia.org/wiki/SQL_injection
解决方案2
1 2012-10-27 23:17:41
Php runs on the server, the htnl output goes to the client. Php在服务器上运行，htnl输出发送到客户端。
Instead of trying to use php to redirect, use javascript or a simple a href. 与其尝试使用php进行重定向，不如使用javascript或简单的href。
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