Call Async Method in Page_Load

问题

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?

回答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();
}

回答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.

回答3:

Try This :

 public void Page_Load(object sender, EventArgs e)
{
    RegisterAsyncTask(new PageAsyncTask(LoadSomeData));
}

public async Task LoadSomeData()
{

    var clientcontacts = Client.DownloadStringTaskAsync("api/contacts");
    var clienttemperature =     Client.DownloadStringTaskAsync("api/temperature");
    var clientlocation = Client.DownloadStringTaskAsync("api/location");

    await Task.WhenAll(clientcontacts, clienttemperature, clientlocation);

    var contacts =     Newtonsoft.Json.JsonConvert.DeserializeObject<List<Contact>>(await clientcontacts);
    var location = Newtonsoft.Json.JsonConvert.DeserializeObject<string>(await clientlocation);
    var temperature = Newtonsoft.Json.JsonConvert.DeserializeObject<string>(await clienttemperature);

    listcontacts.DataSource = contacts;
    listcontacts.DataBind();
    Temparature.Text = temperature;
    Location.Text = location;
}

来源：https://stackoverflow.com/questions/34204450/call-async-method-in-page-load

标签

ASP.NET

.net

async-await