C#•2y ago

❔ multiple Async responses

So im trying to use async for the first time, i am making a few api requests one after the other, the issue is that the order gets mixed up since the requests are being made asynchronously. I need a way of ensuring the order is enforced

61 Replies

jcotton42•2y ago

wdym "order gets mixed up"? can you show the $code, and say what you're expecting to happen? (and what's actually happening)

MODiX•2y ago

To post C# code type the following: ```cs // code here ``` Get an example by typing $codegif in chat If your code is too long, post it to: https://paste.mod.gg/

BoggoOP•2y ago

its messy, but sure

private void FillMessages()
        {
            var messages = _db.GetTextMsgsByServerId(_currServer.ServerId);
            while (messages.Count > 0)
            {
                var message = messages.Pop();
                DisplayNewMessage(message);
            }
        }

private void FillMessages()
        {
            var messages = _db.GetTextMsgsByServerId(_currServer.ServerId);
            while (messages.Count > 0)
            {
                var message = messages.Pop();
                DisplayNewMessage(message);
            }
        }

this gets messages from the database, then displays each one in turn theres some catches below shit wrong bit

Angius•2y ago

Nothing here is async so far

Doombox•2y ago

was about to say, but my name could come in handy soon sunglas

BoggoOP•2y ago

private async void DisplayNewMessage(TextMessage message)
        {
            if (message == null)
            {
                MessageBox.Show("empty message");
                return;
            }

            var settings = UserSettings.Load();
            if (settings.LanguageCode != null)
            {
                var http = new HttpClient();
                var response = await Task.Run(() => http.GetStringAsync($"myapi").Result);
                response = response.Substring(17, response.Length - 19); //removes response information causing error converting to JObject
                var translatedMsg = JObject.Parse(response);
                var output = translatedMsg["text"]?.ToString();

                MessagesLB.Invoke((MethodInvoker)delegate
                {
                    MessagesLB.Items.Add($"{_db.GetClient(message.FromUser).UserName}: {output}");
                });
                return;
            }
            MessagesLB.Invoke((MethodInvoker)delegate
            {
                MessagesLB.Items.Add($"{_db.GetClient(message.FromUser).UserName}: {message.Content}");
            });
        }

private async void DisplayNewMessage(TextMessage message)
        {
            if (message == null)
            {
                MessageBox.Show("empty message");
                return;
            }

            var settings = UserSettings.Load();
            if (settings.LanguageCode != null)
            {
                var http = new HttpClient();
                var response = await Task.Run(() => http.GetStringAsync($"myapi").Result);
                response = response.Substring(17, response.Length - 19); //removes response information causing error converting to JObject
                var translatedMsg = JObject.Parse(response);
                var output = translatedMsg["text"]?.ToString();

                MessagesLB.Invoke((MethodInvoker)delegate
                {
                    MessagesLB.Items.Add($"{_db.GetClient(message.FromUser).UserName}: {output}");
                });
                return;
            }
            MessagesLB.Invoke((MethodInvoker)delegate
            {
                MessagesLB.Items.Add($"{_db.GetClient(message.FromUser).UserName}: {message.Content}");
            });
        }

Angius•2y ago

Nothing async yet Well, async void

jcotton42•2y ago

var response = await Task.Run(() => http.GetStringAsync($"myapi").Result);

that's not async

BoggoOP•2y ago

var response

Angius•2y ago

And await Task.Run() for some reason

jcotton42•2y ago

just await GetStringAsync directly

BoggoOP•2y ago

no task?

Angius•2y ago

This is a doozy of a line lmao

Doombox•2y ago

why would you wrap an awaitable tasks .Result in task.run

jcotton42•2y ago

Task.Run is for shunting CPU-bound work to the thread pool

Doombox•2y ago

Angius•2y ago

It's an awaited task that runs an asynchronous method in a blocking, non-asynchronous context lol

jcotton42•2y ago

it is unnecessary here

BoggoOP•2y ago

my friend said the same thing but wasnt sure how to explain so ive come here

jcotton42•2y ago

the use of .Result is also completely wrong

Angius•2y ago

You're stripping the asynchronicity away with that .Result then you add it back with Task.Run() A zero sum

jcotton42•2y ago

in any case, you mentioned multiple requests, but I only see the one

Doombox•2y ago

.GetAwaiter().GetResult() if you're going to make an asynchronous method call synchronous by the way, for future reference never .Result

jcotton42•2y ago

oh I see, multiple calls to DisplayNewMessage

BoggoOP•2y ago

first part of the code i sent

Angius•2y ago

DisplayMessage() should be async Task first of all

jcotton42•2y ago

in any case, just because you send multiple requests in a given order, doesn't mean they'll return in that order

BoggoOP•2y ago

thats the issue^ if i cant, ill have to run without async, which i think would be terrible

jcotton42•2y ago

if you want them in parallel, you'll just have to deal with that

Angius•2y ago

I mean,

var stuff = new List<int>();
stuff.Add(await GetIntAsync());
stuff.Add(await GetIntAsync());
stuff.Add(await GetIntAsync());

var stuff = new List<int>();
stuff.Add(await GetIntAsync());
stuff.Add(await GetIntAsync());
stuff.Add(await GetIntAsync());

will ensure the order

jcotton42•2y ago

you could queue up the responses somehow, and then run through that queue

Angius•2y ago

Since one call will wait for another

jcotton42•2y ago

true

BoggoOP•2y ago

would it work, to get all the responses, without adding them to the UI display, and sort them by the "dateSent" property they have

jcotton42•2y ago

yes

BoggoOP•2y ago

then add them all that would work? or this

Angius•2y ago

As long as at no point do you have async void, it'll be fine Because only Task can be awaited

BoggoOP•2y ago

var response = await http.GetStringAsync($"myapi"); oh how do you do your slightly dark background?

Angius•2y ago

`code here`

BoggoOP•2y ago

gotcha ty this here requires private async void

jcotton42•2y ago

no it doesn't use async Task async Task is the async version of void you should only use async void when you have to

Angius•2y ago

T => async Task<T> int => async Task<int> void => async Task

BoggoOP•2y ago

ok i see i think its a little better now, going to try the sorting thing i had

Angius•2y ago

void is nothing. Nothing cannot be awaited, cannot be cancelled, cannot be queued... because it doesn't exist. So you need a something, a Task is that something

BoggoOP•2y ago

that makes a lot of sense, until now void was just "doesnt return anything"

jcotton42•2y ago

it still is

BoggoOP•2y ago

which is still true, just very vague ^^yup well thanks guys, had some input from everyone which was nice :)) until next time trying to use this, once the code hits the await get async part, it stops executing and returns to the UI as it seems

Angius•2y ago

Ah, you're using WPF or some such?

BoggoOP•2y ago

winforms

Angius•2y ago

Uh, yeah, at some point you'd need to use... what was it, Dispatcher.Invoke() or something? I don't have much experience with GUI frameworks

BoggoOP•2y ago

hm ok, it was working fine before, with the same api request code from within one Task, can i make multiple api requests?

Angius•2y ago

Sure

BoggoOP•2y ago

this does not work

private async Task<List<TextMessage>> TranslateMessages(Stack<TextMessage> messages)
        {
            var orderedMsgs = new List<TextMessage>();
            var settings = UserSettings.Load();
            

            while (messages.Count > 0)
            {
                var message = messages.Pop();
                var http = new HttpClient();
                var response = await http.GetStringAsync($"myapi");
                response = response.Substring(17, response.Length - 19); //removes response information causing error converting to JObject
                var translatedMsg = JObject.Parse(response);
                message.Content translatedMsg["text"]?.ToString();
                orderedMsgs.Add(message);
            }
            return orderedMsgs;
        }

private async Task<List<TextMessage>> TranslateMessages(Stack<TextMessage> messages)
        {
            var orderedMsgs = new List<TextMessage>();
            var settings = UserSettings.Load();
            

            while (messages.Count > 0)
            {
                var message = messages.Pop();
                var http = new HttpClient();
                var response = await http.GetStringAsync($"myapi");
                response = response.Substring(17, response.Length - 19); //removes response information causing error converting to JObject
                var translatedMsg = JObject.Parse(response);
                message.Content translatedMsg["text"]?.ToString();
                orderedMsgs.Add(message);
            }
            return orderedMsgs;
        }

this will work, just not in order

private async Task DisplayNewMessage(TextMessage message)
        {
            if (message == null)
            {
                MessageBox.Show("empty message");
                return;
            }

            var settings = UserSettings.Load();
            if (settings.LanguageCode != null)
            {
                var http = new HttpClient();
                var response = await http.GetStringAsync($"myapi");
                response = response.Substring(17, response.Length - 19); //removes response information causing error converting to JObject
                var translatedMsg = JObject.Parse(response);
                var output = translatedMsg["text"]?.ToString();

                MessagesLB.Invoke((MethodInvoker)delegate
                {
                    MessagesLB.Items.Add($"{_db.GetClient(message.FromUser).UserName}: {output}");
                });
                return;
            }
            MessagesLB.Invoke((MethodInvoker)delegate
            {
                MessagesLB.Items.Add($"{_db.GetClient(message.FromUser).UserName}: {message.Content}");
            });
        }

private async Task DisplayNewMessage(TextMessage message)
        {
            if (message == null)
            {
                MessageBox.Show("empty message");
                return;
            }

            var settings = UserSettings.Load();
            if (settings.LanguageCode != null)
            {
                var http = new HttpClient();
                var response = await http.GetStringAsync($"myapi");
                response = response.Substring(17, response.Length - 19); //removes response information causing error converting to JObject
                var translatedMsg = JObject.Parse(response);
                var output = translatedMsg["text"]?.ToString();

                MessagesLB.Invoke((MethodInvoker)delegate
                {
                    MessagesLB.Items.Add($"{_db.GetClient(message.FromUser).UserName}: {output}");
                });
                return;
            }
            MessagesLB.Invoke((MethodInvoker)delegate
            {
                MessagesLB.Items.Add($"{_db.GetClient(message.FromUser).UserName}: {message.Content}");
            });
        }

the http request is the same

Angius•2y ago

Don't instantiate a new client with each loop iteration

BoggoOP•2y ago

ah i had it above actually, i moved it inside to check since thats what the second version is effectively doing

Angius•2y ago

Yeah, idk, As I said, I'm not the best at desktop stuff, let alone Winforms @jcotton42 might know more?

BoggoOP•2y ago

all good, appreciate the time regardless, just threw it in here hoping someone might stumble across it again

jcotton42•2y ago

anyControl.Invoke iirc

BoggoOP•2y ago

im unsure what that means

jcotton42•2y ago

the Invoke method on any control like someTextBox.Invoke, someCheckBox.Invoke etc.

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ multiple Async responses