PHP - Manual: filter_input

2024-12-22

filter_input

(PHP 5 >= 5.2.0, PHP 7, PHP 8)

filter_input — 通过名称获取特定的外部变量，并且可以通过过滤器处理它

说明

filter_input(
    int $type,
    string $variable_name,
    int $filter = FILTER_DEFAULT,
    mixed $options = ?
): mixed

参数

type

INPUT_GET, INPUT_POST, INPUT_COOKIE, INPUT_SERVER或 INPUT_ENV之一。

variable_name

待获取的变量名。

filter

The ID of the filter to apply. The Types of filters manual page lists the available filters.

If omitted, FILTER_DEFAULT will be used, which is equivalent to FILTER_UNSAFE_RAW. This will result in no filtering taking place by default.

options

一个选项的关联数组，或者按位区分的标示。如果过滤器接受选项，可以通过数组的 "flags" 位去提供这些标示。

返回值

如果成功的话返回所请求的变量。如果过滤失败则返回 false ，如果variable_name 不存在的话则返回 null 。如果标示 FILTER_NULL_ON_FAILURE 被使用了，那么当变量不存在时返回 false ，当过滤失败时返回 null 。

范例

示例 #1 一个 filter_input() 的例子


<?php
$search_html = filter_input(INPUT_GET, 'search', FILTER_SANITIZE_SPECIAL_CHARS);
$search_url = filter_input(INPUT_GET, 'search', FILTER_SANITIZE_ENCODED);
echo "You have searched for $search_html.\n";
echo "<a href='?search=$search_url'>Search again.</a>";
?>

以上例程的输出类似于：

You have searched for Me &#38; son.
<a href='?search=Me%20%26%20son'>Search again.</a>

参见

filter_var() - 使用特定的过滤器过滤一个变量
filter_input_array() - 获取一系列外部变量，并且可以通过过滤器处理它们
filter_var_array() - 获取多个变量并且过滤它们
Types of filters

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User Contributed Notes 15 notes

down

CertaiN ¶

8 years ago


This function provides us the extremely simple solution for type filtering.

Without this function...
<?php
if (!isset($_GET['a'])) {
    $a = null;
} elseif (!is_string($_GET['a'])) {
    $a = false;
} else {
    $a = $_GET['a'];
}
$b = isset($_GET['b']) && is_string($_GET['b']) ? $_GET['b'] : '';
?>

With this function...
<?php
$a = filter_input(INPUT_GET, 'a');
$b = (string)filter_input(INPUT_GET, 'b');
?>

Yes, FILTER_REQUIRE_SCALAR seems to be set as a default option. 
It's very helpful for eliminating E_NOTICE, E_WARNING and E_ERROR. 
This fact should be documented.

down

rimelek at rimelek dot hu ¶

7 years ago


If your $_POST contains an array value:
<?php
$_POST  = array(
    'var' => array('more', 'than', 'one', 'values')
);
?>
you should use FILTER_REQUIRE_ARRAY option:
<?php
var_dump(filter_input(INPUT_POST, 'var', FILTER_DEFAULT , FILTER_REQUIRE_ARRAY));
?>
Otherwise it returns false.

down

anthony dot parsons at manx dot net ¶

14 years ago


FastCGI seems to cause strange side-effects with unexpected null values when using INPUT_SERVER and INPUT_ENV with this function. You can use this code to see if it affects your server:
<?php
var_dump($_SERVER);
foreach ( array_keys($_SERVER) as $b ) {
    var_dump($b, filter_input(INPUT_SERVER, $b));
}
echo '<hr>';
var_dump($_ENV);
foreach ( array_keys($_ENV) as $b ) {
    var_dump($b, filter_input(INPUT_ENV, $b));
}
?>
If you want to be on the safe side, using the superglobal $_SERVER and $_ENV variables will always work. You can still use the filter_* functions for Get/Post/Cookie without a problem, which is the important part!

down

ss23 at ss23 dot geek dot nz ¶

11 years ago


Note that this function doesn't (or at least doesn't seem to) actually filter based on the current values of $_GET etc. Instead, it seems to filter based off the original values.
<?php
$_GET['search'] = 'foo'; // This has no effect on the filter_input

$search_html = filter_input(INPUT_GET, 'search', FILTER_SANITIZE_SPECIAL_CHARS);
$search_url = filter_input(INPUT_GET, 'search', FILTER_SANITIZE_ENCODED);
echo "You have searched for $search_html.\n";
echo "<a href='?search=$search_url'>Search again.</a>";
?>

If you need to set a default input value and filter that, use filter_var on your required input variable instead

down

Stefan Weinzierl ¶

8 years ago


Here is an example how to work with the options-parameter. Notice the 'options' in the 'options'-Parameter!

<?php
$options=array('options'=>array('default'=>5, 'min_range'=>0, 'max_range'=>9));

$priority=filter_input(INPUT_GET, 'priority', FILTER_VALIDATE_INT, $options);
?>

$priority will be 5 if the priority-Parameter isn't set or out the given range.

down

chris at chlab dot ch ¶

10 years ago


To use a class method for a callback function, as usual, provide an array with an instance of the class and the method name.
Example:

<?php
class myValidator
{
  public function username($value)
  {
    // return username or boolean false
  }
}

$myValidator = new myValidator;
$options = array('options' => array($myValidator, 'username'));
$username = filter_input(INPUT_GET, 'username', FILTER_CALLBACK, $options);
var_dump($username);
?>

down

akshay dot leadindia at gmail dot com ¶

8 years ago


The beauty of using this instead of directly using filter_var( $_GET['search'] ) is that you don't need to check if( isset( $_GET['search'] ) ) as if you pass that to filter_var and the key is not set then it will result in a warning. This function simplifies this and will return the relevant result to you (as per your options set) if the key has not been set in the user input. 

If the type of filter you are using also supports a 'default' argument then this function will also stuff your missing input key with that value, again saving your efforts

down

descartavel1+php at gmail dot com ¶

8 years ago


contrary to what is stated here on the comments on thow to use the options for filters, there is no range option or default... in fact, there is not much option AT ALL. It is not mentioned in the manual anywhere, and the provided code on that comment does nothing with php-5.4.4..

<?php
get(GET, 'p', FILTER_VALIDATE_INT, array('options'=>array('default'=>5, 'min_range'=>0, 'max_range'=>9)) );
// ?p=30 => 30
// ?p="123" => 123
// ?p=-23 => -23
// ?p=asdf => null
?>

down

travismowens at gmail dot com ¶

11 years ago


I wouldn't recommend people use this function to store their data in a database.  It's best not to encode data when storing it, it's better to store it raw and convert in upon the time of need.

One main reason for this is because if you have a short CHAR(16) field and the text contains encoded characters (quotes, ampersand) you can easily take a 12 character entry which obviously fits, but because of encoding it no longer fits.

Also, while not as common, if you need to use this data in another place, such as a non webpage (perhaps in a desktop app, or to a cell phone SMS or to a pager) the HTML encoded data will appear raw, and now you have to decode the data.

In summary, the best way to architect your system, is to store data as raw, and encode it only the moment you need to.  So this means in your PHP upon doing a SQL query, instead of merely doing an   echo $row['title']  you need to run htmlentities() on your echos, or better yet, an abstract function.

down

-3

DoubleT ¶

3 years ago


Discovered interesting behavior when modifying super-globals directly.
$_GET['p'] = 1;
filter_input(INPUT_GET,'p'); //value is NULL

Is this expected?

down

-6

west {:a7} jsausa {:d0t}~ com ¶

9 years ago


It's worth noting that the names for variables in filter input obey the same rules as variable naming in PHP (must start with an underscore or letter).  We were allowing users to build custom forms but hashing the names to prevent them from putting arbitrary content into the dom.  Turns out the hash function occasionally produced entirely numeric values for the field name... which doesn't work with filter_input but worked fine if you read directly from $_GET, $_POST, or $_REQUEST.  A workaround is to always prefix an underscore to the field name.

down

-5

Maksym Karazeev ¶

13 years ago


Just a tip. 


Note how to setup default filter for filter_var_array


When I tried to use filter_var_array and didn't mentioned all array indexes in definition it filtered it with some filter and broke values so using this tip corrected everything


<?php

$def = array_map(create_function('', 'return array("filter"=>FILTER_UNSAFE_RAW);'), $input);

?>

down

-5

Enrique ¶

3 years ago


Para obtener el IP de cliente en sustitución de $_SERVER("REMOTE_ADDR") no se puede usar filter_input(INPUT_SERVER,'REMOTE_ADDR',FILTER_VALIDATE_IP) pues devuelve null, la formula que funciona es:

$REMOTE_ADDR = filter_input(INPUT_ENV, 'REMOTE_ADDR', FILTER_VALIDATE_IP);

down

-14

viaujoc at videotron dot ca ¶

7 years ago


filter_input() does not seem to support multiple values for a single variable name.

Here is the code comparing the behavior of bare $_GET superglobal vs filter_input(INPUT_GET,...):
<?php
print("Bare \$_GET:\n");
var_dump($_GET);
print("filter_input():\n");
var_dump(filter_input(INPUT_GET,"var"));
?>

When calling: /..../script.php?var=123 (there is only one value for variable 'var')
Output is:
Bare $_GET:
array(1) {
  ["var"]=>
  string(3) "123"
}
filter_input():
string(3) "123"

When calling: /..../script.php?var[]=123&var[]=999 (there are two  values for variable 'var')
Output is:
Bare $_GET:
array(1) {
  ["var"]=>
  array(2) {
    [0]=>
    string(3) "123"
    [1]=>
    string(3) "999"
  }
}
filter_input():
bool(false)

As expected, $_GET['var'] became an array. But filter_input() seems to be unable to process multiple values and returns false.

down

-22

John Smith ¶

7 years ago


1. The description of the options parameter is misleading. In order to pass the options (e.g. default, min_range and max_range) you must pass an associative array with a key called "options", which itself is an associative array containing option name => option value pairs.

2. The return values section does not mention that if you specify the "default" option then the function will return the specified default value instead of returning FALSE or NULL (when filter fails or variable is absent).

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官方地址：https://www.php.net/manual/en/function.filter-input.php

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filter_input

说明

参数

返回值

范例

参见

User Contributed Notes 15 notes