How to get Json Post Values with asp.net webapi

First way:

    public void Post([FromBody]dynamic value)
    {
        var x = value.var1.Value; // JToken
    }

Note that value.Property actually returns a JToken instance so to get it's value you need to call value.Property.Value.

Second way:

    public async Task Post()
    {        
        dynamic obj = await Request.Content.ReadAsAsync<JObject>();
        var y = obj.var1;
    }

Both of the above work using Fiddler. If the first option isn't working for you, try setting the content type to application/json to ensure that the JsonMediaTypeFormatter is used to deserialize the content.

After banging my head around for a while on this and trying many different things I ended up putting some breakpoints on the API server and found the key value pairs stuffed down in the request. After I knew where they were, it was easy to access them. However, I have only found this method to work with WebClient.UploadString. However, it does work easily enough and allows you to load up as many parameters as you like and very easily access them server side. Note that I am targeting .net 4.5.

CLIENT SIDE

// Client request to POST the parameters and capture the response
public string webClientPostQuery(string user, string pass, string controller)
{
    string response = "";

    string parameters = "u=" + user + "&p=" + pass; // Add all parameters here.
    // POST parameters could also easily be passed as a string through the method.

    Uri uri = new Uri("http://localhost:50000/api/" + controller); 
    // This was written to work for many authorized controllers.

    using (WebClient wc = new WebClient())
    {
        try
        {
            wc.Headers[HttpRequestHeader.ContentType] = "application/x-www-form-urlencoded";
            response = wc.UploadString(uri, login);
        }
        catch (WebException myexp)
        { 
           // Do something with this exception.
           // I wrote a specific error handler that runs on the response elsewhere so,
           // I just swallow it, not best practice, but I didn't think of a better way
        }
    }

    return response;
}

SERVER SIDE

// In the Controller method which handles the POST request, call this helper:
string someKeyValue = getFormKeyValue("someKey");
// This value can now be used anywhere in the Controller.
// Do note that it could be blank or whitespace.

// This method just gets the first value that matches the key.
// Most key's you are sending only have one value. This checks that assumption.
// More logic could be added to deal with multiple values easily enough.
public string getFormKeyValue(string key)
{
    string[] values;
    string value = "";
    try
    {
        values = HttpContext.Current.Request.Form.GetValues(key);
        if (values.Length >= 1)
            value = values[0];
    }
    catch (Exception exp) { /* do something with this */ }

    return value;
}

For more info on how to handle multi-value Request.Form Key/Value pairs, see:

http://msdn.microsoft.com/en-us/library/6c3yckfw(v=vs.110).aspx

I searched all morning to find an answer that depicted both client and server code, then finally figured it out.

Brief intro - The UI is an MVC 4.5 project that implements a standard view. The server side is an MVC 4.5 WebApi. The objective was to POST the model as JSON and subsequently update a database. It was my responsibility to code both the UI and backend. Below is the code. This worked for me.

Model

public class Team
{
    public int Ident { get; set; }
    public string Tricode { get; set; }
    public string TeamName { get; set; }
    public string DisplayName { get; set; }
    public string Division { get; set; }
    public string LogoPath { get; set; }
}

Client Side (UI Controller)

    private string UpdateTeam(Team team)
    {
        dynamic json = JsonConvert.SerializeObject(team);
        string uri = @"http://localhost/MyWebApi/api/PlayerChart/PostUpdateTeam";

        try
        {
            WebRequest request = WebRequest.Create(uri);
            request.Method = "POST";
            request.ContentType = "application/json; charset=utf-8";
            using (var streamWriter = new StreamWriter(request.GetRequestStream()))
            {
                streamWriter.Write(json);
                streamWriter.Flush();
                streamWriter.Close();
            }
            WebResponse response = (HttpWebResponse)request.GetResponse();
            using (var streamReader = new StreamReader(response.GetResponseStream()))
            {
                var result = streamReader.ReadToEnd();
            }
        }
        catch (Exception e)
        {
            msg = e.Message;
        }
    }

Server Side (WebApi Controller)

    [Route("api/PlayerChart/PostUpdateTeam")]
    [HttpPost]
    public string PostUpdateTeam(HttpRequestMessage context)
    {
        var contentResult = context.Content.ReadAsStringAsync();
        string result = contentResult.Result;
        Team team = JsonConvert.DeserializeObject<Team>(result);

        //(proceed and update database)
    }

WebApiConfig (route)

        config.Routes.MapHttpRoute(
            name: "PostUpdateTeam",
            routeTemplate: "api/PlayerChart/PostUpdateTeam/{context}",
            defaults: new { context = RouteParameter.Optional }
        );