 +        $properties = [];
 +        foreach ($book as $colName => $colValue) {
 +            $propName = $this->columns[$colName] . 'Value';
-+            $properties[$colName] = [
-+                 $propName => $colValue
-+            ];
++            if (! empty($colValue)) {
++                $properties[$colName] = [
++                    $propName => $colValue
++                ];
++            }
 +        }
 +
 +        return $properties;

+        // Use "NON_TRANSACTIONAL" for simplicity (as we're only making one call)
+        $request = new \Google_Service_Datastore_CommitRequest([
+            'mode' => 'NON_TRANSACTIONAL',
+            'mutation' => [
+                'delete' => [$key]
+            ]
+        ]);
+

+        // Use "NON_TRANSACTIONAL" for simplicity (as we're only making one call)
+        $request = new \Google_Service_Datastore_CommitRequest([
+            'mode' => 'NON_TRANSACTIONAL',
+            'mutations' => [
+                [
+                    'update' => $entity
+                ]
+            ]
+        ]);
+
