WPF Live Charts - XAML code not linking to C# code

Question

I'm struggling with live charts. I'm using WPF.

I want to build a bar chart that displays the number of members in a Karate Club by belt color. One of my learning projects.

Following their docs: https://lvcharts.net/App/examples/v1/wpf/Basic%20Column

I am getting an error in xaml:

d:DataContext="{d:DesignInstance local:Charts}" 'The name "Charts" does not exist in namespace "clr-namespace:KarateClub" '

and

LabelFormatter="{Binding Formatter}" 'Method Formatter not found in type Charts'

If I remove the DataContext code the graph displays but it doesn't use any of my values. I must be missing how to link the XAML code to the C# code...? Have I got the class/namespace path wrong?

My XAML Code:

<UserControl x:Class="KarateClub.Charts"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:KarateClub"
             xmlns:lvc="clr-namespace:LiveCharts.Wpf;assembly=LiveCharts.Wpf"
             mc:Ignorable="d" 
             d:DesignHeight="400" d:DesignWidth="1000" d:DataContext="{d:DesignInstance local:Charts}" >

    <Grid Background="White" Width="1000" Height="550">
        <Grid Background="White" Margin="33,45,239,170">
            <lvc:CartesianChart Series="{Binding SeriesCollection}" LegendLocation="Left">
                <lvc:CartesianChart.AxisX>
                    <lvc:Axis Title="Belts" Labels="{Binding Labels}"></lvc:Axis>
                </lvc:CartesianChart.AxisX>
                <lvc:CartesianChart.AxisY>
                    <lvc:Axis Title="Members" LabelFormatter="{Binding Formatter}"></lvc:Axis>
                </lvc:CartesianChart.AxisY>
            </lvc:CartesianChart>
        </Grid>
    </Grid>
</UserControl>

My C# Code:

using System;
using System.Windows.Controls;
using LiveCharts;
using LiveCharts.Wpf;

namespace KarateClub
{
    public partial class Charts : UserControl
    {

        public SeriesCollection SeriesCollection { get; set; }
        public string[] Labels { get; set; }
        public Func<double, string> Formatter { get; set; }


        public Charts()
        {
            InitializeComponent();

            SeriesCollection = new SeriesCollection
            {
                new ColumnSeries
                {
                    Title = "2020",
                    Values = new ChartValues<double> { 1, 5, 3, 5, 7, 3, 9, 2, 3 }
                }
            };

            Labels = new[] { "White", "Yellow", "Orange", "Green", "Blue", "Purple", "Brown", "Red", "Black" };
            Formatter = value => value.ToString("N");

            DataContext = this;

        }
    }
}

Answer 1

You are currently using a design-time instance of Charts , which is generated by the designer. This instance is auto-generated and doesn't contain any data. This is the default behavior, which is controlled by the IsDesignTimeCreatable property of the markup extension DesignInstanceExtension . By default IsDesignTimeCreatable returns false , which directs the designer to create a fake instance using reflection (bypassing any constructor).

To use a design-time instance of the specified type which is properly constructed, you have to set this property explicitly to true :

<UserControl x:Class="KarateClub.Charts"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:KarateClub"
             d:DataContext="{d:DesignInstance local:Charts, IsDesignTimeCreatable=True}" >
  ...
</UserControl>

Now the designer will create an instance using the constructor instead of using reflection.

Apparently this Blend design-time attributes are not well documented. To learn more see Microsoft Docs: Design-Time Attributes in the Silverlight Designer

Answer 2

The example you are following does not say d:DataContext="{d:DesignInstance local:Charts}" .

it says d:DataContext="{d:DesignInstance local:BasicColumn}" .