CODEWITHSUNDEEP
listviewmvvmxamarin.forms
Gustavo Piucco
Gustavo Piucco

Reputation: 557

Xamarin.Forms MVVM implementation to populate XAML ListView through OnApperaing event

I have a async rest service that create a List<> when page is loaded through OnAppearing event.

protected async override void OnAppearing()
{
     base.OnAppearing();

     RestService restService = new RestService();
     List<Example> exampleList = await restService.GetExample();
}

What is the best practice to populate XAML ListView with exampleList when async operation is ready using MVVM pattern?

Upvotes: 0

Views: 1166

Answers (1)

JordanMazurke
JordanMazurke

Reputation: 1123

I personally provide a base ContentPage implementation and in there point events to an interface that is implemented in the view model. E.G.

public interface IPageAppearingEvent
{
    void OnAppearing();
}

public class BasePage : ContentPage
{
    protected override void OnBindingContextChanged ()
    {
        base.OnBindingContextChanged ();

        var onAppearingLifeCycleEvents = BindingContext as IPageAppearingEvent;
        if (onAppearingLifeCycleEvents != null) {
            var lifecycleHandler = onAppearingLifeCycleEvents;

            base.Appearing += (object sender, EventArgs e) => lifecycleHandler.OnAppearing ();
        }
    }
}

public class ViewModel : IPageAppearingEvent
{
    public void OnAppearing()
    {
        //Do whatever you like in here
    }
}

As long as you ensure your views are subclasses of the BasePage then you are good to go.

Upvotes: 3

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