Edit file File name : CollectionEntityTestPrimaryKeyString.php Content :<?php namespace QuadLayers\WP_Orm\Tests\Collection; class CollectionEntityTestPrimaryKeyString extends \QuadLayers\WP_Orm\Entity\CollectionEntity { /** * @var string */ public static $primaryKey = 'test_id'; public $test_id = ''; public $key1 = 'default_value_1'; public $key2 = 'default_value_2'; public $key3 = [ 'key_3_1' => 'default_value_3', 'key_3_2' => 'default_value_4', ]; public function __construct() { } } Save