[Enhancement] EmptyView for BindableLayout

[hartez]

Summary

Add an EmptyView property to BindableLayout which, when set, displays if there are no other items in the layout.

This is basically a duplicate of the EmptyView feature on CollectionView.

API Changes

In BindableLayout, add:

public static readonly BindableProperty EmptyViewProperty = BindableProperty.Create(nameof(EmptyView), typeof(object), typeof(Layout<View>), null);

public static readonly BindableProperty EmptyViewTemplateProperty = BindableProperty.Create(nameof(EmptyViewTemplate), typeof(DataTemplate), typeof(Layout<View>), null);

Intended Use Case

In the following example, if ItemsSource contains any items, they will be displayed in the StackLayout and EmptyView will not be visible. If ItemSource contains no items, the EmptyView will be displayed as the sole element in the StackLayout.

<StackLayout BindableLayout.ItemsSource="{Binding ItemsSource}">
    <BindableLayout.EmptyView>
        <Label Text="No Results"/>
    </BindableLayout.EmptyView>
</StackLayout>

If EmptyViewTemplate is set, the template content will be displayed with EmptyView as the binding context for the template content.

If EmptyViewTemplate is not set, the following rules apply:

• If the content of EmptyView is a simple string, that string is displayed as a Label.
• If the content of EmptyView is a Forms element, that element is displayed.
• Otherwise, the EmptyView object's ToString(InvariantCulture) representation is displayed as a Label.

[Eilon]

I am a Xamarin Forms user, and I approve this message.

[ChaseFlorell]

I was just coming here to ask for the same thing!

Right now we use this, and it's ugly and a pain.

<StackLayout BindableLayout.ItemsSource="{Binding SomeList}">
    <!-- -->
</StackLayout>
<Label Text="No Results" IsVisible="{Binding SomeList, Converter={StaticResource HasValueConverter}}"