I currently have json using json_encode from a mysql query which looks like this:
{\"post_2\":{\"caption\":\"...\",\"id\":\"...\",\"accountID\":\"..\",\"date
Provide a non-associative array to json_encode(). The easiest way is usually to simply call array_values() on the (associative) array, and encode the result.
json_encode()
array_values()
Take a look at PHP's json_decode function, specifically the 2nd parameter if you want an array.