Develop Reference

MessageBox.Show sporadically don't show on catching exception

I am writing a Visual Studio extension in C# and I get a strange behavior on managing exception and displaying error messages. Basically, I just want to add some details to the exception message to help me investigate in case of a problem.
It all starts from a command on a context menu item and I suspect it may be related to threads management behind the async/await mechanism. But I am not sure I guess correctly and I am not able to find any solution. HELP!
It starts from my menu item callback:
internal sealed class My_RunAnalysis
{
//...
public static async Task InitializeAsync(AsyncPackage package)
{
// Switch to the main thread - the call to AddCommand in PS_RunAnalysis's constructor requires
// the UI thread.
await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync(package.DisposalToken);
OleMenuCommandService commandService = await package.GetServiceAsync((typeof(IMenuCommandService))) as OleMenuCommandService;
Instance = new My_RunAnalysis(package, commandService);
}
//...
private async void ExecuteAsync(object sender, EventArgs e)
{
try
{
await My_ViewModel.RunAnalysisAsync();
}
catch (Exception exc)
{
await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync(package.DisposalToken);
MessageBox.Show(exc.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Warning);
}
}
}
//...
class My_ViewModel
{
async public static Task RunAnalysisAsync()
{
await My_Model.GetResultsListAsync();
}
}
//...
class My_Model
async public static Task GetResultsListAsync()
{
ResultsList = new My_ResultsList();
var rawResultsList = await QueryServerAsync<RawResultsListResponse>("GET", My_Request.GetResults());
//...
}
async public static Task<JsonResponse> QueryServerAsync<JsonResponse>(string method,
string request)
{
try
{
HttpResponseMessage response;
switch (method)
{
case "GET":
response = await _httpClient.GetAsync(request);
break;
case "POST":
default:
StringContent httpContent = new StringContent("", Encoding.UTF8, "application/json");
response = await _httpClient.PostAsync(request, httpContent);
break;
}
if (!response.IsSuccessStatusCode) //<<<<<<CASE #1
{
throw new My_Exception(
response.ReasonPhrase,
"Exception while querying server for " + request);
}
string serializedJson = await response.Content.ReadAsStringAsync();
// CASE #2>>>>>
var jsonResponse = serializer.Deserialize<JsonResponse>(serializedJson);
return jsonResponse;
}
catch (Exception e)
{
throw new My_Exception(
e.Message,
"Exception while querying server for " + request);
}
}
The strange thing is that:
When an error occurs in case #1 and I create a custom exception (my server responded but there was an internal error and I have a clean error code), the MessageBox in the catch of My_ViewModel::RunAnalysisAsync() will show correctly and immediately.
When a native exception occurs in case #2 (my server responded with malformed json and I get an exception from serializer.Deserialize), the MessageBox in the catch of My_ViewModel::RunAnalysisAsync() will not show, the IDE will hang for around 15s before restarting (and still not show the MessageBox).
Any idea what's wrong?
Thanks!
EDIT:
Seeing that the template for my custom command initializes also with SwitchToMainThreadAsync, I have tried to do the same with the Execute method. I updated the code above but it still does not work: an exception thrown by serializer.Deserialize will still freeze the UI for 10 to 15s and the MessageBox will not show!
Also note that the debugger can step immediately on "await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync(package.DisposalToken);" and go on next step to MessageBox. I would tend to suppose it means that the switch to the main thread is immediate but there is still something wrong...
Any idea what's wrong? I really need to capture exceptions a reliable way...

I could not find any explanation to the MessageBox working on a case and not on the other one. I ended up going to some log solution using FileStream.WriteAsync. Hence everything keeps async and I don't have to use MessageBox anymore.

use await JoinableTaskFactory.SwitchToMainThreadAsync(); to switch to the main thread JoinableTaskFactory is a member of AsyncPackage.
If it still doesn't work try
public static void ShowMessageBox(string title, string text)
{
Microsoft.VisualStudio.Shell.ThreadHelper.ThrowIfNotOnUIThread();
IVsUIShell uiShell = Microsoft.VisualStudio.Shell.ServiceProvider.GlobalProvider.GetService(typeof(SVsUIShell)) as IVsUIShell;
Guid clsid = Guid.Empty;
int result;
Microsoft.VisualStudio.ErrorHandler.ThrowOnFailure(uiShell.ShowMessageBox(
0,
ref clsid,
title,
text,
string.Empty,
0,
OLEMSGBUTTON.OLEMSGBUTTON_OK,
OLEMSGDEFBUTTON.OLEMSGDEFBUTTON_FIRST,
OLEMSGICON.OLEMSGICON_INFO,
0, // false
out result));
}

Different response from bot emulator and chatbot in web

I have created a chatbot in web channel and direct line.
When i tested in bot emulator i get the right response and when i try to test the same intent in localhost ( webchat) i got different response.
I will show you and example :
call an agent
give me your customer number
( after custemer number was sended ) are you sure ?
if you click Yes ...the data are stored in database ( sql server )
If you do the save in localhost you get : You cancelled the form ( in fact i havent cancell any form
Here is the luisdialog here i call the form :
[LuisIntent("human")]
public async Task human(IDialogContext context, LuisResult result)
{
var form = new FormDialog<Human>(
new Human(),
Human.BuildForm,
FormOptions.PromptInStart,
result.Entities);
context.Call<Human>(form, LossFormCompleted)
}
private async Task LossFormCompleted(IDialogContext context,
IAwaitable<Human> result)
{
HumanCall form = null;
try
{
form = await result;
}
catch (OperationCanceledException)
{
}
if (form == null)
{
await context.PostAsync("You cancelled the form.");
}
else
{
//call the LossForm service to complete the form fill
var message = $"Your data are stored in database";
await context.PostAsync(message);
}
context.Wait(this.MessageReceived);
}
The form model is :
[Serializable]
public class Human
{
[Prompt("What is your contract number?")]
public string contract;
public static IForm<Human> BuildForm()
{
OnCompletionAsyncDelegate<HumanCall> wrapUpRequest = async (context, state) =>
{
using (BotModelDataContext BotDb = new BotModelDataContext())
{
tblBot bot = new tblBot();
bot = BotDb.tblBots.SingleOrDefault(q => q.Reference == state.contract);
if (bot != null)
{
using (bbbserviceSoapClient cws = new bbbserviceSoapClient())
{
viewc a= new viewc();
a.Lastname = bot.Lastname;
}
}
}
};
return new FormBuilder<Human>().Message
("can you send us some info ?")
.Field(nameof(contract))
.OnCompletion(wrapUpRequest)
.Confirm("Are you sure: Yes or No. ")
.Build();
}
}
}
Can someone help me where i'm wrong ? What can i do to retrieve the same response ? It's about timeout problem or what do you thing ?

I do a test based on the code that you provided and make slight modifications, and I find that if some exceptions occur in wrapUpRequest method, it would show "You cancelled the form" instead of the message "Your data are stored in database".
So I suspect that exceptions occurring in wrapUpRequest method (perhaps database query issue or request sent by bbbserviceSoapClient is timeout etc) when you do test via web chat, which causes the issue.
To troubleshoot the issue, you can try to implement/write custom log to detect if any exception occurs within wrapUpRequest method when you test via web chat.

Discord bot running, but will not connect to server

I've been trying to swap over my code from the 0.9.6 Discord.NET API to the new 1.0.1 API, and it's basically calling for a complete restructure to my code. But I've been having some trouble actually getting the bot up and running first of all.
I set up the code body according to the guide linked here
And while it runs without error, the bot itself is not appearing online in my server.
And before you ask, I had in fact replaced "Bot token here" with the actual bot token.
namespace DiscordBot{
public class Program
{
private CommandService commands;
private DiscordSocketClient client;
private IServiceProvider services;
static void Main(string[] args) => new Program().Start().GetAwaiter().GetResult();
public async Task Start()
{
client = new DiscordSocketClient();
commands = new CommandService();
string token = "<token>";
services = new ServiceCollection()
.BuildServiceProvider();
await InstallCommands();
await client.LoginAsync(TokenType.Bot, token);
await client.StartAsync();
await Task.Delay(-1);
}
public async Task InstallCommands()
{
// Hook the MessageReceived Event into our Command Handler
client.MessageReceived += HandleCommand;
// Discover all of the commands in this assembly and load them.
await commands.AddModulesAsync(Assembly.GetEntryAssembly());
}
public async Task HandleCommand(SocketMessage messageParam)
{
// Don't process the command if it was a System Message
var message = messageParam as SocketUserMessage;
if (message == null) return;
// Create a number to track where the prefix ends and the command begins
int argPos = 0;
// Determine if the message is a command, based on if it starts with '!' or a mention prefix
if (!(message.HasCharPrefix('!', ref argPos) || message.HasMentionPrefix(client.CurrentUser, ref argPos))) return;
// Create a Command Context
var context = new CommandContext(client, message);
// Execute the command. (result does not indicate a return value,
// rather an object stating if the command executed successfully)
var result = await commands.ExecuteAsync(context, argPos, services);
if (!result.IsSuccess)
await context.Channel.SendMessageAsync(result.ErrorReason);
}
}
}
And then for the MyBot.cs class
namespace DiscordBot
{
class MyBot : ModuleBase
{
private CommandService _service;
public MyBot(CommandService service)
{
_service = service;
}
}
}

The first thing you might want to do is add some logging to your bot.
As your code might be correct, but discord could be rejecting your connection for any amount of reason.
After await client.StartAsync(); add
client.Log += (msg) => {return Console.WriteLine(${msg.ToString()}");};`
This will output the message your receive from your client to the console.
Now you also need to configure which message should be send to this event. This can be done when creating your DiscordClient(). So instead of client = new DiscordSocketClient(); You could use
client = new DiscordSocketClient(
new DiscordSocketConfig()
{
LogLevel = LogSeverity.Verbose
}
);
Verbose should give you all the information you need. However you could also use LogSeverity.Debug instead, which is the highest available logging, and therefore would give you all messages.
Now that you have some feedback in your console, go and see what concrete errors you are having.
Also I would recommend first completing the your first bot part of the linked tutorial, instead of stepping into the commands directly. Once you got this working, you can continue onwards

gRPC with WPF not working

I am trying to get the gRPC C# example working inside WPF.
The same code which is working inside a Console Application is not working. What am I missing.
The minimal class which works in the Console App and does not work in WPF looks like this:
public class GrpcClientImpl
{
private GrpcService.GrpcService.GrpcServiceClient client;
public GrpcTestClientImpl()
{
var channel = new Channel("127.0.0.1:6980", ChannelCredentials.Insecure);
client = new GrpcService.GrpcService.GrpcServiceClient(channel);
ProcessFeed().Wait();
}
public async Task ProcessFeed()
{
try
{
using (var call = client.Feed(new FeedRequest()))
{
var responseStream = call.ResponseStream;
while (await responseStream.MoveNext())
{
var result = responseStream.Current;
Console.WriteLine("received result");
}
}
}
catch (RpcException e)
{
Console.WriteLine("RPC failed " + e);
throw;
}
}
}
The responseStream.MoveNext() is where it is hanging. It does not respond to sent items and it does also not trigger an exception if the gRPC server is not there. What have I missed?

The problem is the blocking call ProcessFeed().Wait(); within the constructor.
This post explains why:
http://blog.stephencleary.com/2012/07/dont-block-on-async-code.html
To solve the issue, call await ProcessFeed(); from outside (not in the costructor).

C# SMTP SendAsync not working

I am having an issue using the SendMailAsync When I change it out for a normal Send it works fine. When I use SendMailAsync I get a connection has timed out and no mail is sent. Am I setting it up the wrong way?
edit:
1. I changed the variable name!!!
2.The exact error happens here await smtpClient.SendMailAsync(mailMessage); It just hangs until the connection times out, and I get an error description of "Connection has timed out" The status code returned is General Error
I'm calling the sendEmail from form the onClick event of a button for now. await unitOfWork.Instance.SendEmail(...) It's a single line of code in the onclick event
public async Task SendEmail(List<string> notificationList, string emailSubject, string emailMessage)
{
var message = new MailMessage()
{
IsBodyHtml = true,
BodyEncoding = System.Text.Encoding.UTF8,
Subject = emailSubject,
From = new MailAddress(FromEmailAddress),
Body = emailMessage
};
try
{
foreach (var emailAddress in notificationList)
{
message.To.Add(emailAddress);
}
var people = string.Join(Environment.NewLine, message.To);
MessageBox.Show(#"from: " + unitOfWork.CurrentSystemUser.Person.Email + "To: " + people);
await SendMessage(message);
}
catch (Exception E)
{
...
}
finally
{
...
}
}
private async Task SendMessage(MailMessage mailMessage)
{
if (!CanSendSmtpEmail) return;
await SendSmtpMail(mailMessage);
}
public async Task SendSmtpMail(MailMessage mailMessage)
{
SmtpClient smtpClient = new SmtpClient(SmtpClientHost, int.Parse(SmtpClientPort));
smtpClient.SendCompleted += (s, e) => {
smtpClient.Dispose();
mailMessage.Dispose();
};
await smtpClient.SendMailAsync(mailMessage);
//smtpClient.Send(mailMessage) works fine
}

Increasing SmtpClient.Timeout won't work because it only applies to the synchronous Send method (see here).
Your code is working fine for me when I test it using GMail (like explained here) Can you give it a try with GMail or a different SMTP server? I think maybe your SMTP server is "acting funny". Also maybe you can show us how are you calling SendEmail method ?
Side notes:
Your question is really interesting (at least to me) but because of the way you wrote your code (property has the same name as method) people have down-voted it (you should fix that).
Also, can I see the full exception you get? (btw: catch (Exception E) - not good, use lowercase "e" for the exception argument name).
Make sure you understand exactly how asynchronous it really is.