如何在c＃中运行时将json反序列化为指定的对象

Question

我可以在运行时获得两种类型的json

1

{ "op":"put_message",
  "args":"create_time":1386590144.372,
  "user_ids":["jin.raj1381386731048.15195712",
              "shami.gulug1378102436530.59079906",
              "sweth.pilli1378100716736.58912086",
              "sai_n.gavar1378384157577.59878517"],
  "groups":[]
}

2

{
  "op":"put_message",
  "args":"create_time":1386590144.372,
  "user_ids":"jin.raj1381386731048.15195712",
  "groups":[]
}

user_ids可以是List<string>，也可以是string .. 那么如何使用JsonConvert libray基于user_id反序列化呢？