如何在 MVC4 中将 Json 字符串输出为 JsonResult

This seems so simple I must be over-thinking it.

TL;DR;

如何修改下面的代码以返回字符串中包含的json对象，而不是恰好包含json的字符串？

public ActionResult Test()
{
  var json_string = "{ success: \"true\" }";
  return Json(json_string, JsonRequestBehavior.AllowGet);
}

This code returns a string literal containing the json:

"{ success: "true" }"

但是，我希望它返回字符串中包含的json:

{ success: "true" }

Slightly longer version

I'm trying to quickly prototype some external api calls and just want to pass those results through my "api" as a fake response for now. The json object is non-trivial - something on the order of 10,000 "lines" or 90KB. I don't want to make a strongly typed object(s) for all the contents of this one json response just so I can run it through a deserializer - so that is out.

所以我的控制器的基本逻辑是:

1. 调用外部所有接口
2. Store string result of web request into a var (see json_string above)
3. Output those results as json (not a string) using the JsonResult producing method Json()

Any help is greatly appreciated... mind is melting.