Don't filter non numeric values

Author: Peter Schwab

app/code/Magento/Eav/Model/Entity/Attribute/Backend/ArrayBackend.php

@@ -58,12 +58,14 @@ public function validate($object)
 
     /**
      * Prepare attribute values
-     *
-     * @param array $data
-     * @return string
      */
     private function prepare(array $data): string
     {
-        return implode(',', array_filter(array_unique($data), 'is_numeric'));
+        return implode(
+            ',',
+            array_filter(
+                array_unique($data),
+                fn($value) => is_numeric($value) || !empty($value))
+        );
     }
 }

app/code/Magento/Eav/Test/Unit/Model/Entity/Attribute/Backend/ArrayBackendTest.php

@@ -87,6 +87,26 @@ public static function validateDataProvider(): array
                 ['sku' => 'test1', 'attr' => '0,1,2,3,4'],
                 true,
                 '0,1,2,3,4'
+            ],
+            'keeps non numeric values from string' => [
+                ['sku' => 'test1', 'attr' => 'foo,bar'],
+                true,
+                'foo,bar'
+            ],
+            'keeps non numeric values from array' => [
+                ['sku' => 'test1', 'attr' => ['foo','bar']],
+                true,
+                'foo,bar'
+            ],
+            'filters empty values from string' => [
+                ['sku' => 'test1', 'attr' => 'foo,bar,,123'],
+                true,
+                'foo,bar,123'
+            ],
+            'filters empty values from array' => [
+                ['sku' => 'test1', 'attr' => ['foo','bar','',null,123]],
+                true,
+                'foo,bar,123'
             ]
         ];
     }