The easiest way is to use JSON_OBJECT for everything. Fastest would be just writing to device from resultset. Combine these approaches to get the performance you need (add this code to Parent class and call Test method)
Another check. Properties can't be SQL reserved words. I often name properties "Date", etc. only to forget that they can't be used in SQL as is only quoted, so I need to go to Class view and rename them to something else.