How can I utilize compiled binding inside Application.Resources for say a StyleTrigger of type DataTrigger bound to a feild in the ViewModel?

Question

For example, If I have this Style block inside my Application.Resources.

and lets say inside the contentview where I have the ViewModel binded and DataType set (x:DataType"ViewModels:MyViewModel"), let's say I have a

<StackLayout Style="{StaticResource ProductFrame}">

With compiled binding, shouldn't that Product.Title property from the ViewModel be recognized? Is this a bug or a limitation because the DataType doesn't seem to apply to anything inside Style blocks and it doesn't seem to pass down to Static Style resources when applied to a parent view in the page xaml. However, the data does of course bind no problem.

Answer 1

Hello,​

Welcome to our Microsoft Q&A platform!

lets say inside the contentview where I have the ViewModel binded and DataType set (x:DataType"ViewModels:MyViewModel"),

Firstly, I add following styles in Application.Resources, for testing, I set the Frame's background to red, BorderColor to Green.

   <Application.Resources>  
           <Style x:Key="ProductFrame" TargetType="{x:Type Frame}">  
               <Style.Triggers>  
                   <DataTrigger TargetType="{x:Type Frame}" Binding="{Binding TestProperty}" Value="True">  
                       <Setter  Property="BackgroundColor" Value="Red"/>  
                       <Setter Property="BorderColor" Value="Green"></Setter>  
                   </DataTrigger>  
               </Style.Triggers>  
           </Style>  
       </Application.Resources>  

Then I create a contentView called View1.Xaml.

   <ContentView xmlns="http://xamarin.com/schemas/2014/forms"   
                xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"   
                xmlns:local="clr-namespace:App27"  
                x:Class="App27.View1">  
     <ContentView.Content>  
     
           <StackLayout x:DataType="local:MyViewModelColor">  
               <StackLayout.BindingContext>  
                   <local:MyViewModelColor />  
               </StackLayout.BindingContext>  
                 
                 
               <Frame Padding="24" CornerRadius="0" Style="{StaticResource ProductFrame}">  
                   <Label Text="Welcome to Xamarin.Forms!" HorizontalTextAlignment="Center" TextColor="White" FontSize="36"/>  
               </Frame>  
           </StackLayout>  
     </ContentView.Content>  
   </ContentView>  

MyViewModelColor.cs just have a property called TestProperty that used in ProductFrame's style.

It worked, here is my running screenshot.

Best Regards,

Leon Lu

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