Xamarin.Forms (XAML): Different layouts depending on a condition - xaml

Question

Is there a way to choose what layout initialize depending on one condition? I have a Grid for football stats but if myViewModel.Sport == Sports.Basketball I'd like to load a completely different layout.
I tried something like this with Datatrigger in each View but it seems a mess for me:
<Label Text="{Binding Goals}"
Grid.Row="1" Grid.Column="0">
<Label.Triggers>
<DataTrigger TargetType="Label"
Binding="{Binding Sport}"
Value="1">
<Setter Property="Text"
Value="{Binding Points}"/>
</DataTrigger>
</Label.Triggers>
</Label>
I show "goals" but if the Sports enum value is 1 (Sports.Basketball) I change to "points". I want to do this with lots of Labels and even Images so I need a proper way to do it.
Could someone help me? I need to load a different Grid depending on the Sport Property of my ViewModel.

Answer 1

Another thing you could do is place each separate sport into it's own view, add all the views to your page and set their IsVisible property depending on which sport you want to show.
An example would look like this in pseudo-code:
<Page>
<Grid>
<BasketballView IsVisible="{Binding IsBasketball}">
<SoccerView IsVisible="{Binding IsSoccer}">
<FootballView IsVisible="{Binding IsFootball}">
</Grid>
</Page>
Then set the appropriate boolean values from the ViewModel.

Answer 2

To use DataTemplateSelector to solve this, as mentioned by #StephaneDelcroix, you'll want a custom class that has ItemsSource and ItemTemplate properties.
I haven't thought through / tested how DataTemplateSelector would be used with this; anyone is welcome to add that to this answer.
using System.Collections;
using Xamarin.Forms;
namespace YourNamespace
{
// From https://forums.xamarin.com/discussion/19874/listview-inside-stacklayout-a-height-problem/p2, #maxx313.
public class TemplatedStack : StackLayout
{
public static readonly BindableProperty ItemsSourceProperty = BindableProperty.Create("ItemsSource", typeof(IList), typeof(TemplatedStack), propertyChanged: OnItemsSourceChanged);
public IList ItemsSource
{
get { return (IList)GetValue(ItemsSourceProperty); }
set { SetValue(ItemsSourceProperty, value); }
}
private static void OnItemsSourceChanged(BindableObject pObj, object pOldVal, object pNewVal)
{
var layout = pObj as TemplatedStack;
if (layout != null && layout.ItemTemplate != null)
{
layout.BuildLayout();
layout.ForceLayout();
}
}
public static readonly BindableProperty ItemTemplateProperty = BindableProperty.Create("ItemTemplate", typeof(DataTemplate), typeof(TemplatedStack), propertyChanged: OnItemTemplateChanged);
public DataTemplate ItemTemplate
{
get { return (DataTemplate)GetValue(ItemTemplateProperty); }
set { SetValue(ItemTemplateProperty, value); }
}
private static void OnItemTemplateChanged(BindableObject pObj, object pOldVal, object pNewVal)
{
var layout = pObj as TemplatedStack;
if (layout != null && layout.ItemsSource != null)
layout.BuildLayout();
}
private void BuildLayout()
{
Children.Clear();
foreach (var item in ItemsSource)
{
var view = (View)ItemTemplate.CreateContent();
view.BindingContext = item;
Children.Add(view);
}
}
protected override SizeRequest OnMeasure(double widthConstraint, double heightConstraint)
{
return base.OnMeasure(widthConstraint, heightConstraint);
}
}
}
In your XAML, do
<yourXmlns:TemplatedStack .../>
where yourXmlns must be an xmlns declaration at top of your XAML.
Usage of ItemsSource and ItemTemplate properties is similar to how you would bind an items collection and template to a ListView.
(The reason NOT to use a ListView here, is that ListView may interfere with touch events, and adds extra layout cost.)
Bind to this a collection containing a single item.
E.g. for this question, that item would be the specific sport being viewed.