Something interesting which might help someone else:
If your input field in HTML is "disabled", even if it contains text, $_POST will not return/contain any value.
As an alternative, you can use "readonly" in your input field.
$_POST -- $HTTP_POST_VARS [已弃用] — HTTP POST 变量
当 HTTP POST 请求的 Content-Type 是 application/x-www-form-urlencoded 或 multipart/form-data 时，会将变量以关联数组形式传入当前脚本。
$HTTP_POST_VARS 包含相同的信息，但它不是一个超全局变量。 (注意 $HTTP_POST_VARS 和 $_POST 是不同的变量，PHP 处理它们的方式不同)
| 版本 | 说明 |
|---|---|
| 4.1.0 | 引入 $_POST，弃用 $HTTP_POST_VARS。 |
Example #1 $_POST 范例
<?php
echo 'Hello ' . htmlspecialchars($_POST["name"]) . '!';
?>
假设用户通过 HTTP POST 方式传递了参数 name=Hannes
以上例程的输出类似于：
Hello Hannes!
Note:
"Superglobal"也称为自动化的全局变量。这就表示其在脚本的所有作用域中都是可用的。不需要在函数或方法中用 global $variable; 来访问它。
Something interesting which might help someone else:
If your input field in HTML is "disabled", even if it contains text, $_POST will not return/contain any value.
As an alternative, you can use "readonly" in your input field.
There's an earlier note here about correctly referencing elements in $_POST which is accurate. $_POST is an associative array indexed by form element NAMES, not IDs. One way to think of it is like this: element "id=" is for CSS, while element "name=" is for PHP. If you are referring to your element ID in the POST array, it won't work. You must assign a name attribute to your element to reference it correctly in the POST array. These two attributes can be the same for simplicity, i.e.,
<input type="text" id="txtForm" name="txtForm">...</input>
I know it's a pretty basic thing but I had issues trying to access the $_POST variable on a form submission from my HTML page. It took me ages to work out and I couldn't find the help I needed in google. Hence this post.
Make sure your input items have the NAME attribute. The id attribute is not enough! The name attribute on your input controls is what $_POST uses to index the data and therefore show the results.
Note that $_POST is NOT set for all HTTP POST operations, but only for specific types of POST operations. I have not been able to find documentation, but here's what I've found so far.
$_POST _is_ set for:
Content-Type: application/x-www-form-urlencoded
In other words, for standard web forms.
$_POST is NOT set for:
Content-Type:text/xml
A type used for a generic HTTP POST operation.
One feature of PHP's processing of POST and GET variables is that it automatically decodes indexed form variable names.
I've seem innumerable projects that jump through extra & un-needed processing hoops to decode variables when PHP does it all for you:
Example pseudo code:
Many web sites do this:
<form ....>
<input name="person_0_first_name" value="john" />
<input name="person_0_last_name" value="smith" />
...
<input name="person_1_first_name" value="jane" />
<input name="person_1_last_name" value="jones" />
</form>
When they could do this:
<form ....>
<input name="person[0][first_name]" value="john" />
<input name="person[0][last_name]" value="smith" />
...
<input name="person[1][first_name]" value="jane" />
<input name="person[1][last_name]" value="jones" />
</form>
With the first example you'd have to do string parsing / regexes to get the correct values out so they can be married with other data in your app... whereas with the second example.. you will end up with something like:
<?php
var_dump($_POST['person']);
//will get you something like:
array (
0 => array('first_name'=>'john','last_name'=>'smith'),
1 => array('first_name'=>'jane','last_name'=>'jones'),
)
?>
This is invaluable when you want to link various posted form data to other hashes on the server side, when you need to store posted data in separate "compartment" arrays or when you want to link your POSTed data into different record handlers in various Frameworks.
Remember also that using [] as in index will cause a sequential numeric array to be created once the data is posted, so sometimes it's better to define your indexes explicitly.
For a page with multiple forms here is one way of processing the different POST values that you may receive. This code is good for when you have distinct forms on a page. Adding another form only requires an extra entry in the array and switch statements.
<?php
if (!empty($_POST))
{
// Array of post values for each different form on your page.
$postNameArr = array('F1_Submit', 'F2_Submit', 'F3_Submit');
// Find all of the post identifiers within $_POST
$postIdentifierArr = array();
foreach ($postNameArr as $postName)
{
if (array_key_exists($postName, $_POST))
{
$postIdentifierArr[] = $postName;
}
}
// Only one form should be submitted at a time so we should have one
// post identifier. The die statements here are pretty harsh you may consider
// a warning rather than this.
if (count($postIdentifierArr) != 1)
{
count($postIdentifierArr) < 1 or
die("\$_POST contained more than one post identifier: " .
implode(" ", $postIdentifierArr));
// We have not died yet so we must have less than one.
die("\$_POST did not contain a known post identifier.");
}
switch ($postIdentifierArr[0])
{
case 'F1_Submit':
echo "Perform actual code for F1_Submit.";
break;
case 'Modify':
echo "Perform actual code for F2_Submit.";
break;
case 'Delete':
echo "Perform actual code for F3_Submit.";
break;
}
}
else // $_POST is empty.
{
echo "Perform code for page without POST data. ";
}
?>