DataService.cs

DataService.cs

public class DataService  
{
   public async Task<string> MakeRequest(RequestBase req)
   {
	if (req == null)
        {
            throw new ArgumentNullException("req");
        }
	   
	 //creating http message
	 HttpRequestMessage message = PrepareMessageGraphQL(req);
	  
	 //creating http response
	 HttpResponseMessage response = await HttpClient.SendAsync(message);
	   
	  //if empty return error
	  if (response == null)
          {		 
               throw new Exception("The server did not return a response.");
          }

          if (response.IsSuccessStatusCode)
          {
		return  await response.Content.ReadAsStringAsync();
	  }
	  //if status code is not success
	  else
	  {
		throw new Exception($"Server returned status code {response.StatusCode}.");
	  }	    
   }
	
	
	
    private async Task<HttpRequestMessage> PrepareMessageGraphQL(RequestBase req)
    {
        HttpRequestMessage message = null;

        //Creating a POST Request Message		
        message = new HttpRequestMessage(HttpMethod.Post, ApiConstants.GRAPHQL_URL);
 
        //Setting the content of the query
        message.Content = new StringContent(req.ParamsToCall, Encoding.UTF8, "application/json");
        
	//you might want to set some headers?
        //message.Headers.Add("Authorization", "Bearer WithToken");
	 
        return message;
   }
}