유틸리티 함수 추가

src/sammo/Json.php

@@ -27,6 +27,9 @@ class Json
 
     public static function decode($value)
     {
+        if($value === null){
+            return null;
+        }
         return json_decode($value, true);
     }
 

src/sammo/Util.php

@@ -269,6 +269,17 @@ class Util extends \utilphp\util
         return $result;
     }
 
+    public static function pickArrayFromArrayOfDictWithKey(array $arrayOfDict, string $key):array{
+        $result = [];
+        foreach($arrayOfDict as $array){
+            if(!key_exist($key, $array)){
+                continue;
+            }
+            $result[] = $array[$key];
+        }
+        return $result;
+    }
+
     public static function convertArrayToDict($arr, $keyName)
     {
         $result = [];