added not empty check for string

src/Utils/Dbo/LuStringDbo.php

@@ -64,6 +64,11 @@ class LuStringDbo extends LuDbo
         }
     }
 
+    public function notEmpty($trim = true)
+    {
+        static::min(1, $trim);
+    }
+
     public function min($min, $trim = true)
     {
         if (self::getLength($trim) < $min) {