Edit file File name : SingleEntityTest.php Content :<?php namespace QuadLayers\WP_Orm\Tests\Single; class SingleEntityTest extends \QuadLayers\WP_Orm\Entity\SingleEntity { public static $sanitizeProperties = [ 'key1' => 'strval', 'key2' => 'strval', 'key3' => self::class . '::sanitizeKey3', 'key4' => 'self::sanitizeKey4', 'key5' => '$this->sanitizeKey5', ]; public string $key1 = 'default_value_1'; public string $key2 = 'default_value_2'; public string $key3 = '3'; public int $key4 = 3; public string $key5 = 'Test Alternative'; public static function sanitizeKey3($value) { if (is_numeric($value)) { return (string) $value; } return '0'; } public static function sanitizeKey4($value) { return (int) $value; } public function sanitizeKey5($value = null) { return 'Test Alternative'; } } Save