Declaring Design-Time ViewModel for Avalonia Window

user_3960200 0
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I'm looking for the right approach to declare design-time ViewModel for an Avalonia window.

Some samples suggest

d:DataContext="{d:DesignInstance viewModels:LoginViewModel, IsDesignTimeCreatable=True}"

This throws

XamlParseException at 5:5: Unable to resolve type DesignInstance from namespace http://schemas.microsoft.com/expression/blend/2008

Default Avalonia MVVM template suggests

<Design.DataContext>
    <vm:MainWindowViewModel/>
</Design.DataContext>

If the ViewModel takes parameters, it throws

XamlLoadException at 16:10: Unable to find public constructor for type Demo.CloseNonModalDialog:Demo.CloseNonModalDialog.CurrentTimeDialogViewModel()

I guess adding a default parameter-less constructor is an option.

With MvvmLight/WPF, I used to reference the ViewLocator as a static resource

DataContext="{Binding Source={StaticResource Locator}, Path=MainWindow}"

That's an option, although I haven't yet found the right way to declare and reference the resource.

What is the recommended approach here? If I want to show design-time data, I'd say only the 3rd option would work. Which is not the option shown in samples.

avaloniaui mvvm .net c#
1 Answers

Unable to find public constructor for type Demo.CloseNonModalDialog:Demo.CloseNonModalDialog.CurrentTimeDialogViewModel()

You can specify arguments via x:Arguments XAML directive, see https://docs.microsoft.com/en-us/dotnet/desktop/xaml-services/xarguments-directive

That's an option, although I haven't yet found the right way to declare and reference the resource.

I'd suggest to declare DesignData class and use x:Static, it will give you way more flexibility. e. g.

class DesignData
{
    public MyViewModel MyViewModel => new MyViewModel(...);
}

d:DataContext="{x:Static local:DesignData.MyViewModel}"

View model creation would also not happen during the normal app execution unlike the StaticResource approach.

user_22318140
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