Exception while setting the XAxes

[juchom]

Hello,

I'm learning Avalonia and XAML, and I have an exception that I don't understand.

namespace ViewModelsSamples.Bars.Basic;

public partial class ViewModel : ObservableObject
{
    public List<double> MaryValues { get; set; } =
        [2, 5, 4];

    public List<double> AnaValues { get; set; } =
        [3, 1, 6];

    [ObservableProperty] public List<string> Labels { get; set; } =
        ["Category 1", "Category 2", "Category 3"];
}

And the XAML

<UserControl
    x:Class="AvaloniaSample.Bars.Basic.View"
    xmlns="https://github.com/avaloniaui"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:lvc="clr-namespace:LiveChartsCore.SkiaSharpView.Avalonia;assembly=LiveChartsCore.SkiaSharpView.Avalonia"
    xmlns:vms="clr-namespace:ViewModelsSamples.Bars.Basic;assembly=ViewModelsSamples"
    x:DataType="vms:ViewModel">

    <UserControl.DataContext>
        <vms:ViewModel/>
    </UserControl.DataContext>

    <lvc:CartesianChart>

        <lvc:CartesianChart.Series>
            <lvc:XamlColumnSeries SeriesName="Mary" Values="{Binding MaryValues}"/>
            <lvc:XamlColumnSeries SeriesName="Ana" Values="{Binding AnaValues}"/>
        </lvc:CartesianChart.Series>

        <lvc:CartesianChart.XAxes>
            <lvc:XamlAxis
                Labels="{Binding Labels}"/>
        </lvc:CartesianChart.XAxes>

    </lvc:CartesianChart>
</UserControl>

If I run this code in an empty project it works.

If I run it In my application, with many things around as you can expect, this does not work and throws an exception.

Unhandled exception. System.Relfection.TargetInvocationException: Exception has been thrown by the target of invocation.
 ---> System.NotSupportedException: StringArrayTypeConverter cannot convert from Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindingExtensions.

And If I comment the XAxes the application works.

Since I'm very new to the XAML / Avalonia world, do you have any advice on how I should troubleshoot this kind of exception ?

Thanks in advance

[juchom]

So changing the XAML to

    <lvc:CartesianChart  XAxes={Binding XAxes}>

        <lvc:CartesianChart.Series>
            <lvc:XamlColumnSeries SeriesName="Mary" Values="{Binding MaryValues}"/>
            <lvc:XamlColumnSeries SeriesName="Ana" Values="{Binding AnaValues}"/>
        </lvc:CartesianChart.Series>

    </lvc:CartesianChart>

And the MVVM model to

namespace ViewModelsSamples.Bars.Basic;

public partial class ViewModel : ObservableObject
{
    public List<double> MaryValues { get; set; } =
        [2, 5, 4];

    public List<double> AnaValues { get; set; } =
        [3, 1, 6];

    [ObservableProperty] private Axis[] _xAxes = { new Axis { Labels = new List<string>() } };
}

Works fine and I don't have a single clue why is this working...

Would be intersting if anyone can explain what is happening

[HaganeNoRenkinjutsu]

Maybe if you specified it as <lvc:XamlAxis Labels="{Binding Path=Labels}" />, that could work? It appears your compiler is not fully "realizing" the path here and is thus trying to convert a literal string into an IList, and hence your StringArrayTypeConverter error. Usually, though, binding the entire XAxes collection has been the most stable approach for me in WPF; Livecharts2 wholly-supports MVVM, so it's usually best to instantiate your axes in the ViewModel if you're going to use any sort of Binding.