实用的脚本
Good tips everybody, thanks! A brief summary:
SERVER-SIDE PROCESSING (GET and POST)
<!-- If your form submission WILL NOT WRITE anything on the SERVER-SIDE, use GET -->
<form action="action.php" method="get">
<!-- If your form submission WILL WRITE some data on the SERVER-SIDE, use POST -->
<form action="action.php" method="post">
CLIENT-SIDE PROCESSING (ID and NAME)
<!-- If the CLIENT-SIDE NEEDS to access or modify this field, use the id attribute -->
<input id="firstName" name="firstName" type="text">
<!-- create a script that runs on the CLIENT-SIDE to access and modify the field -->
<script type="javascript">
var firstName = document.getElementById("firstName");
firstName.value = 'some text';
firstName.focus();
</script>
<!-- If the CLIENT-SIDE DOES NOT NEED to access or modify this field, -->
<!-- then there is no need for the ID attribute or a client side script -->
<input name="firstName" type="text">
Note the HTML SYNTAX:
- In <form>, 'get' and 'post' are the VALUE of the attribute named 'method'.
- In <input>, 'id' and 'name' are the NAME of the attribute with values of 'firstName'.
处理表单
PHP 一个很有用的特点体现在它处理 PHP 表单的方式。需要理解的非常重要的原理，是表单的任何元素都在 PHP 脚本中自动生效。请参阅本手册中“PHP 的外部变量”以获取关于在 PHP 中使用表单的详细信息及范例。以下是 HTML 表单的范例：
Example#1 一个简单的 HTML 表单
<form action="action.php" method="post"> <p>姓名: <input type="text" name="name" /></p> <p>年龄: <input type="text" name="age" /></p> <p><input type="submit" /></p> </form>
该表单中并没有什么特殊的地方，其中没有使用任何特殊的标识符。当用户填写了该表单并点击了提交按钮，页面 action.php 将被调用。在该文件中，可以加入如下内容：
Example#2 打印来自表单的数据
你好，<?php echo htmlspecialchars($_POST['name']); ?>。
你 <?php echo (int)$_POST['age']; ?> 岁了。
该脚本的输出可能是：
你好，Joe。你 22 岁了。
Apart from the htmlspecialchars() and (int) parts, it should be obvious what this does. htmlspecialchars() makes sure any characters that are special in html are properly encoded so people can't inject HTML tags or Javascript into your page. For the age field, since we know it is a number, we can just convert it to an integer which will automatically get rid of any stray characters. You can also have PHP do this for you automatically by using the filter extension. PHP 将自动设置 $_POST['name'] 和 $_POST['age'] 变量。在这之前我们使用了超全局变量 $_SERVER，现在我们引入了超全局变量 $_POST，它包含了所有的 POST 数据。请注意我们的表单提交数据的方法（method）。如果使用了 GET 方法，那么表单中的信息将被储存到超全局变量 $_GET 中。如果并不关心请求数据的来源，也可以用超全局变量 $_REQUEST，它包含了所有 GET、POST、COOKIE 和 FILE 的数据。请参阅 import_request_variables() 函数。
也可以在 PHP 中处理 XForms 的输入，尽管可能更喜欢使用长久以来支持良好的 HTML 表单。XForms 目前还不适合初学者使用，但是用户可能对它感兴趣。手册中在“特点”一章有一节对如何处理从 XForum 接收到的数据进行了简短的介绍。
add a note
User Contributed Notes处理表单
wbcarts at juno dot com
06-Oct-2008 03:03
06-Oct-2008 03:03
rosko at zeta dot org dot au
11-Aug-2008 08:55
11-Aug-2008 08:55
@Lord Pacal: the attributes 'name' and 'id' have different intent and are used differently. 'id' uniquely identifies an element in the HTML DOM, whereas 'name' identifies the field that will be transmitted on the form submit. You can omit the 'id' attribute, but not the 'name' attribute.
Where a field requires multiple elements, e.g. radio buttons and check boxes, the 'name' attribute must be the same but the 'id' must be unique for each element.
'id' is useful for linking explicitly to the element, as in the following cases:
* CSS selector by ID
* JavaScript code, e.g. in-browser form validation or active forms
* the target of a <label> element
The last example is one not used nearly enough, as it allows the user to click on the text next to a radio button or check box - a bigger target and thus easier for users not used to using a mouse:
<input type="checkbox" name="example" value="yes" id="example_yes"/>
<label for="example_yes">Yes, I can click on the text and check the box</label>
arnel_milan at hotmail dot com
30-Mar-2008 01:27
30-Mar-2008 01:27
I was so shocked that some servers have a problem regarding the Submit Type Name and gives a "Not Acceptable error" or Error 406.
Consider the example below :
<form action="blah.php" method="POST">
<table>
<tr>
<td>Name:</td>
<td><input type="text" name="name"></td>
</tr>
<tr>
<td colspan="2" align="center">
<input type="submit" name="Submit_btn" id="Submit_btn" value="Send">
</td>
</tr>
</table>
</form>
This very simple code triggers the "Not Acceptable Error" on
PHP Version 5.2.5 and Apache 1.3.41 (Unix) Server.
However to fix this below is the right code:
<form action="blah.php" method="POST">
<table>
<tr>
<td>Name:</td>
<td><input type="text" name="name"></td>
</tr>
<tr>
<td colspan="2" align="center">
<input type="submit" name="Submitbtn" id="Submit_btn" value="Send">
</td>
</tr>
</table>
</form>
The only problem that took me hours to find out is the "_" in the Submit Button.
Hope this help!
Lord Pacal
04-Jan-2008 10:38
04-Jan-2008 10:38
One thing that tripped me up when I was first learning PHP was the use of the NAME attribute in form fields. The current convention is to use the ID attribute instead when creating forms. (Many HTML editors automatically include an ID attribute without a NAME attribute.) Now, I include both the NAME and ID attributes (with the same value) in all my form fields.
For example...
<form method="post">
<input type="text" id="field1">
<input type="submit" value="go">
</form>
If you then have a PHP page requesting the contents of the "field1" field...
<?php echo $_POST["field1"] ?>
...the above form will always return an empty string for "field1".
The solution is to include the NAME attribute...
<form method="post">
<input type="text" id="field1" name="field1">
<input type="submit" value="go">
</form>
With this change, the PHP code will correctly retrieve the value of the "field1" field.
SvendK
09-Nov-2006 12:02
09-Nov-2006 12:02
As Seth mentions, when a user clicks reload or goes back with the browser button, data sent to the server, may be sent again (after a click on the ok button).
It might be wise, to let the server handle whatever there is to handle, and then redirect (a redirect is not visible in the history and thus not reachable via reload or "back".
It cannot be used in this exact example, but as Seth also mentions, this example should be using GET instead of POST
yasman at phplatvia dot lv
05-May-2005 03:18
05-May-2005 03:18
[Editor's Note: Since "." is not legal variable name PHP will translate the dot to underscore, i.e. "name.x" will become "name_x"]
Be careful, when using and processing forms which contains
<input type="image">
tag. Do not use in your scripts this elements attributes `name` and `value`, because MSIE and Opera do not send them to server.
Both are sending `name.x` and `name.y` coordiante variables to a server, so better use them.
sethg at ropine dot com
02-Dec-2003 04:55
02-Dec-2003 04:55
According to the HTTP specification, you should use the POST method when you're using the form to change the state of something on the server end. For example, if a page has a form to allow users to add their own comments, like this page here, the form should use POST. If you click "Reload" or "Refresh" on a page that you reached through a POST, it's almost always an error -- you shouldn't be posting the same comment twice -- which is why these pages aren't bookmarked or cached.
You should use the GET method when your form is, well, getting something off the server and not actually changing anything. For example, the form for a search engine should use GET, since searching a Web site should not be changing anything that the client might care about, and bookmarking or caching the results of a search-engine query is just as useful as bookmarking or caching a static HTML page.