通过JSON发送数据

Question

I want to send JSON from desktop application to the server with mvc wepApi. this is my desktop application code ,that convert data to the JSON and send it.

 private void btnAddUserType_Click(object sender, EventArgs e)
    {
       UserType userType = new UserType();
        userType.UserTypeName = txtUserTypeName.Text;

        string json = JsonConvert.SerializeObject(userType);


        HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create("http://localhost:3852/api/default1");
        httpWebRequest.ContentType = "text/json";
        httpWebRequest.Method = "POST";

        var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream());
        streamWriter.Write(json);


        var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
        var streamReader = new StreamReader(httpResponse.GetResponseStream());
        var responseText = streamReader.ReadToEnd();
    }

and this is my web api

 // POST api/default1
    public void Post([FromBody]string value)
    {
        UserTypeRepository bl = new UserTypeRepository();
        DataContractJsonSerializer js = new DataContractJsonSerializer(typeof(UserType));
        MemoryStream stream = new MemoryStream(Encoding.UTF8.GetBytes(value));
        UserType u = new UserType();
         u = (UserType)js.ReadObject(stream);
        bl.Add(u);
    }

but when post api is calling the Value is null . why?

Answer 1

        using(var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
            streamWriter.Write(json);

You are not flushing nor closing the stream, so basically the data never gets to the api.

My code:

Program.cs - Console App

class Program
{
    static void Main(string[] args)
    {
        var user = new UserModel {Id = 4, FirstName = "Michael", LastName = "Angelo"};
        var json = JsonConvert.SerializeObject(user);
        HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create("http://localhost:56506/api/Values/");
        httpWebRequest.ContentType = "application/json";
        httpWebRequest.Method = "POST";

        using(var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
            streamWriter.Write(json);



        var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
        var streamReader = new StreamReader(httpResponse.GetResponseStream());
        var responseText = streamReader.ReadToEnd();
        Console.WriteLine(responseText);
        Console.ReadKey();
    }
}

UserModel.cs - some data class

public class UserModel
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public int Id { get; set; }
}

ValuesController.cs - WebApi controller from template

public class ValuesController : ApiController
{
    // GET api/values
    public UserModel[] Get()
    {
        return UserProvider.Instance.Get(); // returns some test data
    }

    // GET api/values/5
    public UserModel Get(int id)
    {
        return new UserModel{Id=1,FirstName="John",LastName="Smith"};
    }

    // POST api/values
    public void Post([FromBody]UserModel value)
    {
        if (value == null)  // BREAKPOINT HERE, just to see what's in value
        {
            var x = value;
        }
    }

}

WebApiConfig.cs - default config with added line about Json, but IT WORKS WITHOUT IT -it's so that I can test GET easily in browser etc. ;)

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        // Web API configuration and services

        // Web API routes
        config.MapHttpAttributeRoutes();
        config.Formatters.JsonFormatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/html"));
        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );
    }
}

Result: