CODEWITHSUNDEEP
xamarin.formshttpclient
davecove
davecove

Reputation: 1071

First try at HTTPClient in Xamarin.Forms not working

I know this should be simple, so I am obviously missing something.

I am writing a very simple Xamarin.Forms application with this as the MainPage.xaml.cs of the Shared project.

public partial class MainPage : ContentPage
{
    public MyClass myClassInstance { get; set; }

    public MainPage()
    {
        InitializeComponent();

        DownloadDataAsync();            
    }

    private async void DownloadDataAsync()
    {
        string page = @"http://www.blaw.com:80/foo/bar"; 

        try
        {
            HttpClient client = new HttpClient();
            var uri = new Uri(string.Format(page, string.Empty));

            var response = await client.GetAsync(uri);  <---  BONK!
            if (response.IsSuccessStatusCode)
            {
                var responseString = await response.Content.ReadAsStringAsync();
                XmlSerializer ser = new XmlSerializer(typeof(MyClass));
                using (TextReader tr = new StringReader(responseString))
                {
                    myClassInstance = (MyClass)ser.Deserialize(tr);
                }
            }
            else
                System.Diagnostics.Debug.WriteLine(response.StatusCode.ToString());
        }
        catch (Exception ex)
        {
            System.Diagnostics.Debug.WriteLine(ex.Message);

        }
    }
}

When I run this on my Android device, it never gets past the GetAsync line (marked with <-- BONK!). It doesn't throw an exception, and in never makes it to the if statement, it just returns from the method without doing anything at all.

I have enabled the ACCESS_NETWORK_STATE and INTERNET permissions in the Android Manifest.

What am I missing?

Upvotes: 1

Views: 190

Answers (1)

Mukesh Modhvadiya
Mukesh Modhvadiya

Reputation: 2178

Calling asynchronous method from constructor is not a good idea. This will work in console applications but not on UI applications. Because this will block the UI thread, and control never returns to the code due to deadlock.

If you can call your async method in OnAppearing, it should work fine.

Upvotes: 2

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