rest_sanitize_value_from_schema() returns invalid value when using a schema of type array with a null value

[hogash]

When using the following configuration, you will get an array containing 1 empty string instead of an empty array;

$schema = array(
	'type'  => 'array',
	'items' => [
		'type' => 'string',
	],
);

$value = rest_sanitize_value_from_schema( null, $schema );
var_dump( $value );

The solution for this would be to modify the following line in rest_sanitize_value_from_schema():

$value = preg_split( '/[\s,]+/', $value );

with

$value = preg_split( '/[\s,]+/', $value, null, PREG_SPLIT_NO_EMPTY );

[wpboss]

I have fixed this and test it.

[birgire]

@wpboss I had a look at preg_split() and stumbled upon an interesting comment here:

​https://secure.php.net/manual/en/function.preg-split.php#121475

that null input for the limit will generate an error in strict_type mode in PHP 7.1+

I could verify that with this snippet:

<?php
declare(strict_types=1);
$value = null;
$value = preg_split( '/[\s,]+/', $value, null, PREG_SPLIT_NO_EMPTY );
var_dump( $value );

will generate a fatal error in PHP 7.0+ according to:

​https://3v4l.org/Urmrp

So instead of:

$value = preg_split( '/[\s,]+/', $value, null, PREG_SPLIT_NO_EMPTY );

it looks like one could consider:

$value = preg_split( '/[\s,]+/', $value, -1, PREG_SPLIT_NO_EMPTY );

as already used elsewhere in core.

I have fixed this and test it.

@wpboss I guess you mean manually tested it. It would also be interesting to check if the current unit tests for rest_sanitize_value_from_schema() and the restapi group will run successfully.

[wpboss]

I have fixed as per your suggestion.

[birgire]

Thanks for the update @wpboss

ps: I created a new ticket #45486 for the correction of the inline documentation of rest_sanitize_value_from_schema() that I noticed here.

[earnjam]

This would also be resolved by #43977

[earnjam]

This was fixed in [44546].