llms_filter_input_sanitize_string( string $type, string $variable_name, int[] $flags = array() )

Function used to sanitize user input in a manner similar to the (deprecated) FILTER_SANITIZE_STRING.

Description Description

This function retrieves the raw user input via llms_filter_input() using the FILTER_UNSAFE_RAW filter, strips all tags, and then encodes single and double quotes with the relevant HTML entity codes.

In many cases, the usage of FILTER_SANITIZE_STRING can be easily replaced with FILTER_SANITIZE_FULL_SPECIAL_CHARS but in some cases, especially when storing the user input, encoding all special characters can result in an stored XSS injection so this function can be used to preserve the pre PHP 8.1 behavior where sanitization is expected during the retrieval of user input.

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Parameters Parameters




(string) (Required) Name of a variable to retrieve.


(int[]) (Optional) Array of supported filter options and flags. Accepts FILTER_REQUIRE_ARRAY in order to require the input to be an array. Accepts FILTER_FLAG_NO_ENCODE_QUOTES to prevent encoding of quotes.

Default value: array()

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Return Return

(string|string[]|null|boolean) Value of the requested variable on success, false if the filter fails, or null if the $variable_name variable is not set.

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Source Source

File: includes/llms.functions.core.php

function llms_filter_input_sanitize_string( $type, $variable_name, $flags = array() ) {

	$require_array = in_array( FILTER_REQUIRE_ARRAY, $flags, true );

	$string = llms_filter_input( $type, $variable_name, FILTER_UNSAFE_RAW, $require_array ? FILTER_REQUIRE_ARRAY : array() );

	// If we have an empty string or the input var isn't found we can return early.
	if ( empty( $string ) ) {
		return $string;

	$string = $require_array ? array_map( 'wp_strip_all_tags', $string ) : wp_strip_all_tags( $string );

	if ( ! in_array( FILTER_FLAG_NO_ENCODE_QUOTES, $flags, true ) ) {
		$string = str_replace(
			array( "'", '"' ),
			array( ''', '"' ),

	return $string;

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Changelog Changelog

Version Description
5.9.0 Introduced.

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