Call Async Method in Page_Load

Question

static async void SendTweetWithSinglePicture(string message, string image)
{
    var auth = new SingleUserAuthorizer
    {
        CredentialStore = new SingleUserInMemoryCredentialStore
        {
            ConsumerKey = "",
            ConsumerSecret = "",
            AccessToken = "",
            AccessTokenSecret = ""
        }
    };

    var context = new TwitterContext(auth);

    var uploadedMedia = await context.UploadMediaAsync(File.ReadAllBytes(@image));
    var mediaIds = new List<ulong> { uploadedMedia.MediaID };

    await context.TweetAsync(
        message,
        mediaIds
    );
}
protected void Page_Load(object sender, EventArgs e)
{
    SendTweetWithSinglePicture("test", "path");
}

How can I call a async method on Page_Load?

Solution 1

The question is if you want to make the Page_Load method async or not. If so:

protected async void Page_Load(object sender, EventArgs e)
{
    await SendTweetWithSinglePicture("test", "path");
}

Or if you don't want it to be async:

protected void Page_Load(object sender, EventArgs e)
{
    SendTweetWithSinglePicture("test", "path").Wait();
}

This does require your async method to return Task as it always should! (except event handlers)

The problem with this might be that the method doesn't complete before rendering the page. If it has to, you'd better make the method synchronous, or register the task using Page.RegisterAsyncTask and Page.ExecuteRegisteredAsyncTasks. Effectively this will freeze the Page_Load method too.

protected void Page_Load(object sender, EventArgs e)
{
    PageAsyncTask t = new PageAsyncTask(SendTweetWithSinglePicture("test", "path"));

    // Register the asynchronous task.
    Page.RegisterAsyncTask(t);

    // Execute the register asynchronous task.
    Page.ExecuteRegisteredAsyncTasks();
}

Solution 2

You should use PageAsyncTask. It has samples in MSDN page.

// Register the asynchronous task.
Page.RegisterAsyncTask(new PageAsyncTask(SendTweetWithSinglePicture(message, image));

// Execute the register asynchronous task.
Page.ExecuteRegisteredAsyncTasks();

as I pointed the sample and explanations on MSDN page is pretty good.

Comments

[Ron Beyer]

If you change the method to static async Task instead of void, you can call it by using SendTweetWithSinglePicture("test", "path").Wait(). Avoid async void unless you are using it for events.

[Ron Beyer]

By the way, try to avoid posting your question with your API keys/secrets. Anybody with that information can hijack the API account.

[sara]

@RonBeyer blocking synchronously in an ASP application is begging for a deadlock. Never ever call Task.Wait() if you can at all avoid it. In this case it's possible to simply make Page_Load async, or register an async task using the built-in types of ASP.

[Ron Beyer]

To use Wait the method signature for the SendTweet... needs to be changed to async Task doesn't it?

[mason]

It might be more handy if you showed the actual code instead of solely relying on MSDN.

[Patrick Hofman]

Well, yes. Good point. All async methods should (except event handlers).

[Ron Beyer]

Where is RegisterAsyncTask declared? Please try to avoid "try this" type answers. Answers without explaining what changed and why do not help the OP to understand the problem.

[Dilip Oganiya]

This will surely fixed code. Why you upvoting without any reason ??

[Ron Beyer]

I gave a pretty good explanation in my comment, if you'd like to expand on the answer instead of just "try this" then I'd gladly remove the downvote.

[motime]

Downvoting beacuse he wrote "try this" is pure rubbish. Question was how can you call async code from Page_Load and the answer he gave was accurate.

[Bimal Das]

@hamid , can you tell me why Page.ExecuteRegisteredAsyncTasks() immediately calling the async method? It exit the Page_Load event and execute base master events and then it execute the async task. I want to execute async before calling any other event.

[Theophilus]

The Using Asynchronous Methods in ASP.NET 4.5 article is also helpful. It was written for Visual Studio 2012 and .NET Framework 4.5 but still seems applicable for V.S. 2019 and Framework 4.8.