C# rewrite Restsharp Windows Form Program to Console Program

[zydjohn]

Hi, I want to rewrite a Windows Form program, which uses Restsharp asynchronously, to a console program. As I need to add another async UDP functions. The original Windows Form program can be found here: https://github.com/cenksari/restsharp-apicaller

The Windows Form program works in my Visual Studio 2017 Environment.


The following is my code:

using Newtonsoft;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using RestSharp;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using static AsyncRest1.ApiCaller;

namespace AsyncRest1
{

public class ApiCaller
{
string apiAddress;

public class RestResponse
{
public bool Status { get; set; }
public string Message { get; set; }
public string Response { get; set; }
public string ErrorCode { get; set; }
}

public class RestRequestA
{
public string Method { get; set; }
public string Endpoint { get; set; }
public string Payload { get; set; }
public string Session_Token { get; set; }
}

public ApiCaller()
{
apiAddress = "https://webserver/v1";
}

public async Task<RestResponse> GetEndpoint(RestRequestA apiRequest)
{
RestResponse returnedValue = new RestResponse();
RestClient client = new RestClient();
client.BaseUrl = new Uri(apiAddress);
RestSharp.RestRequest request = new RestSharp.RestRequest(apiRequest.Endpoint);
request.Method = (apiRequest.Method == "POST") ? Method.POST : Method.GET;
request.AddHeader("accept", "application/json");
request.AddHeader("content-type", "application/json");
request.AddHeader("x-authentication", apiRequest.Session_Token);
if (request.Method == Method.POST)
{
request.AddParameter("application/json", apiRequest.Payload, ParameterType.RequestBody);
}
var cancellationTokenSource = new CancellationTokenSource();
var response = await client.ExecuteTaskAsync
(
request,
cancellationTokenSource.Token
);

if (response.StatusCode == System.Net.HttpStatusCode.OK)
{
returnedValue.Status = true;
returnedValue.Response = response.Content;
}
else
{
returnedValue.Status = false;
returnedValue.Message = $"{response.StatusDescription} {response.ErrorMessage}";
returnedValue.Response = response.Content;
returnedValue.ErrorCode = response.StatusCode.ToString();
}
return returnedValue;
}
}

class Program
{
public void Main()
{
var api1 = new ApiCaller();
string token1 = "3699be21-09c8-4fa1-b2ad-9841d31c30";
string payload1 = @"{ ""Name"": ""John Doe""} ";
ApiCaller.RestRequestA request1 = new ApiCaller.RestRequestA
{
Method = "POST",
Endpoint = "https://webserver/v1",
Payload = payload1,
Session_Token = token1
};

var response1 = await api1.GetEndpoint(request1);
Console.ReadKey();
}
}
}

Since the returned result from GetEndpoint is JSon data, so I need Newtonsoft.Json to parse the result. Now I setup my project to use .NET Framework 4.7.1 and C# Version to C# 7.3 (I believe it is the highest version now), and my IDE is Visual Studio 2017 15.7.4, My OS version is Windows 10 Enterprise with latest updates.

However, my program got compiler error:

Error CS4033 The 'await' operator can only be used within an async method. Consider marking this method with the 'async' modifier and changing its return type to 'Task'.

This error seems want me to change public void Main()

To some thing like: public async Task MainAsync()

But if I do so, then I got another compiler error:

Program does not contain a static 'Main' method suitable for an entry point.


Any advice? By the way, for the class RestResponse, I don’t need all information, if there is no error in receiving the response from the HTTPS server, I need only the response’s Content.

By the way, if I use the synchronous way of RestSharp, I can finish the same job without any issue. However, since I have another UDP asynchronous job (receive UDP packets) to do in the same project. So, I have to use RestSharp in an asynchronous way.

Thanks,

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