Funciones de Filter

Tabla de contenidos

filter_has_var — Comprueba si existe una variable de un tipo concreto existe
filter_id — Indica el ID del nombre de filtro que se indique
filter_input — Toma una variable externa concreta por su nombre y opcionalmente la filtra
filter_input_array — Obtiene variables externas y opcionalmente las filtra
filter_list — Devuelve una lista de todos los filtros soportados
filter_var — Filtra una variable con el filtro que se indique
filter_var_array — Retorna múltiple variables y opcionalmente las filtra

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User Contributed Notes 2 notes

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vojtech at x dot cz ¶

17 years ago

Also notice that filter functions are using only the original variable values passed to the script even if you change the value in super global variable ($_GET, $_POST, ...) later in the script.

<?php
echo filter_input(INPUT_GET, 'var'); // print 'something'
echo $_GET['var']; // print 'something'
$_GET['var'] = 'changed';
echo filter_input(INPUT_GET, 'var'); // print 'something'
echo $_GET['var']; // print 'changed'
?>

In fact, external data are duplicated in SAPI before the script is processed and filter functions don't use super globals anymore (as explained in Filter tutorial bellow, section 'How does it work?').

down

fumble1 at web dot de ¶

17 years ago

I recommend you to use the FILTER_REQUIRE_SCALAR (or FILTER_REQUIRE_ARRAY) flags, since you can use array-brackets both to access string offsets and array-element -- however, not only this can lead to unexpected behaviour. Look at this example:

<?php
$image = basename(filter_input(INPUT_GET, 'src', FILTER_UNSAFE_RAW, FILTER_FLAG_STRIP_LOW));
// further checks
?>

/script.php?src[0]=foobar will cause a warning. :-(
Hence my recommendation:

<?php
$image = basename(filter_input(INPUT_GET, 'src', FILTER_UNSAFE_RAW, FILTER_REQUIRE_SCALAR | FILTER_FLAG_STRIP_LOW));
// further checks
?>

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