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How to support example data with view models?
To find out how to create design time data, see the designers topic.
How to use events with MVVM?
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When writing MVVM, it's "forbidden" (read: not a best practice) to use click handlers (or other UI events) in your view-model. But then should you react to events?
- Start with creating a command like you are used to using MVVM. This command will be executed when the event occurs.
- Add a reference to System.Windows.Interactivity.dll (ships with Catel). If you have used NuGet to add a reference, it is automatically included for you.
Add the following namespace definitions to your view declaration:
Code Block xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" xmlns:catel="http://catel.codeplex.com"Use the following code to convert an event to a command:
Code Block <i:Interaction.Triggers> <i:EventTrigger EventName="[YourEvent]"> <catel:EventToCommand Command="{Binding [YourCommand]}" DisableAssociatedObjectOnCannotExecute="False" /> </i:EventTrigger> </i:Interaction.Triggers>
An example for a ListBox double click:
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<ListBox ItemsSource="{Binding PersonCollection}" SelectedItem="{Binding SelectedPerson}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="MouseDoubleClick">
<catel:EventToCommand Command="{Binding Edit}" DisableAssociatedObjectOnCannotExecute="False" />
</i:EventTrigger>
</i:Interaction.Triggers>
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<Label Content="{Binding FirstName}" />
<Label Content="{Binding MiddleName}" />
<Label Content="{Binding LastName}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox> |
Silverlight throws error about type that cannot be created?
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If you are using type creation via xaml this way:
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<i:Interaction.Behaviors>
<catel:WindowBehavior ViewModelType="viewmodels:DemoWindowViewModel" Save="okButton.Click" Cancel="cancelButton.Click" />
</i:Interaction.Behaviors> |
It might be possible that Silverlight throws an exception with these details:
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{System.Windows.Markup.XamlParseException: Failed to create a 'System.Type' from the text 'ViewModels:DemoWindowViewModel'. [Line: 13 Position: 67]
at System.Windows.Application.LoadComponent(Object component, Uri resourceLocator)
at Catel.Examples.AdvancedDemo.Views.LogicInBehavior.DemoWindow.InitializeComponent()
at Catel.Examples.AdvancedDemo.Views.LogicInBehavior.DemoWindow..ctor()} |
This happens in Silverlight 4 when the Silverlight 5 (beta) tools are not installed. To resolve this issue, install the Silverlight 5 (beta) tools.
How can I add the MVVM behaviors via code (programmatically)?
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