asp.net OWIN save the JSON post data - asp.net

Question

I have the setup a test command line app using self hosting OWIN.
I have one test controller and this works as expected to deliver a static home page plus two values in JSON format on a get request.
I'm using the JsonFormatter to format all results.
I would like to read JSON data into it from a post request.
I can send an accepted message response but the data is always null when read.
// POST api/values
[HttpPost]
public HttpResponseMessage Post([FromBody]string myString)
{
Console.WriteLine("Terry Tibbs");
Console.WriteLine(myString);
return new HttpResponseMessage(System.Net.HttpStatusCode.Accepted);
}
I'm using Postman in Chrome to post data as below but myString is always blank.
POST /api/values HTTP/1.1
Host: localhost:8080
Content-Type: application/json
Cache-Control: no-cache
Postman-Token: a966fa36-010d-3e2b-ad66-2f82dcb155ed
{
"myString": "This is new"
}

Answer 1

Read Parameter Binding in ASP.NET Web API
Using [FromBody]
To force Web API to read a simple type from the request body, add the
[FromBody] attribute to the parameter:
public HttpResponseMessage Post([FromBody] string myString) { ... }
In this example, Web API will use a media-type formatter to read the
value of myString from the request body. Here is an example client
request.
POST api/values HTTP/1.1
User-Agent: Fiddler
Host: localhost:8080
Content-Type: application/json
Content-Length: 13
"This is new"
When a parameter has [FromBody], Web API uses the Content-Type header
to select a formatter. In this example, the content type is
"application/json" and the request body is a raw JSON string (not a
JSON object).