PHP Advanced Filters

PHP Advanced Filters Tutorial

PHP advanced filters allow you to validate, sanitize, and process data with more control. You can use options, flags, and filter arrays to handle complex input validation scenarios.

Filter Options

Some filters support options and flags for more control.

Example: Validate Integer with Range

options define additional rules, like minimum and maximum range.

Filter Flags

Flags modify how a filter behaves.

a) Validate URL with Query Component

Common Flags:

Flag	Description
`FILTER_FLAG_ALLOW_HEX`	Allow hexadecimal number for int validation
`FILTER_FLAG_STRIP_LOW`	Remove ASCII <32 for strings
`FILTER_FLAG_STRIP_HIGH`	Remove ASCII >127 for strings
`FILTER_FLAG_ENCODE_LOW`	Encode ASCII <32
`FILTER_FLAG_ENCODE_HIGH`	Encode ASCII >127
`FILTER_FLAG_NO_ENCODE_QUOTES`	Don’t encode quotes

b) Validate IP Address with Flags

FILTER_FLAG_IPV4 → Only allows IPv4
FILTER_FLAG_IPV6 → Only allows IPv6

Using Filter Arrays for Multiple Fields

You can validate multiple inputs at once using an associative array.

<?php
$data = array(
"name" => "Vipul",
"age" => 25,
"email" => "vipul@example.com"
);

$filters = array(
"name" => array(
"filter" => FILTER_SANITIZE_STRING
),
"age" => array(
"filter" => FILTER_VALIDATE_INT,
"options" => array("min_range"=>18, "max_range"=>60)
),
"email" => array(
"filter" => FILTER_VALIDATE_EMAIL
)
);

$result = filter_var_array($data, $filters);

echo "<pre>";
print_r($result);
echo "</pre>";
?>

<?php

$data = array(

"name" => "Vipul",

"age" => 25,

"email" => "vipul@example.com"

);

$filters = array(

"name" => array(

"filter" => FILTER_SANITIZE_STRING

"age" => array(

"filter" => FILTER_VALIDATE_INT,

"options" => array("min_range"=>18, "max_range"=>60)

"email" => array(

"filter" => FILTER_VALIDATE_EMAIL

)

);

$result = filter_var_array($data, $filters);

echo "<pre>";

print_r($result);

echo "</pre>";

Output:

filter_var_array() → apply different filters to multiple fields at once

Sanitize with Flags

FILTER_FLAG_STRIP_HIGH removes non-ASCII characters

Validate Boolean Values

FILTER_NULL_ON_FAILURE returns NULL if value is not boolean

Key Advanced Functions

Function	Purpose
`filter_var()`	Validate/sanitize a single variable
`filter_var_array()`	Validate/sanitize multiple variables
`filter_input()`	Validate input from GET/POST/COOKIE
`filter_input_array()`	Validate multiple inputs from GET/POST/COOKIE

Summary

Advanced filters allow more control over validation and sanitization.
Options define rules like min/max range, default value.
Flags modify how filters behave.
filter_var_array() & filter_input_array() help handle multiple fields at once.
Use advanced filters for secure and robust user input handling.

PHP Advanced Filters