Use multibinding for receipt date format

src/Helpers/DateFormatConverter.cs

@@ -0,0 +1,27 @@
+
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using Avalonia.Data.Converters;
+
+namespace MayShow.Helpers;
+
+public class DateFormatConverter : IMultiValueConverter
+{
+    public object? Convert(
+        IList<object?> values,
+        Type targetType,
+        object? parameter,
+        CultureInfo culture)
+    {
+        if (values.Count >= 2 && values[0] is DateOnly date && values[1] is string format)
+        {
+            return date.ToString(format);
+        }
+        if (values.Count >= 2 && values[0] is string dateFormat && values[1] is DateOnly dateOnly)
+        {
+            return dateOnly.ToString(dateFormat);
+        }
+        return 0.0;
+    }
+}

src/Views/MainView.axaml

@@ -10,6 +10,9 @@
              xmlns:vm="clr-namespace:MayShow.ViewModels"
              xmlns:progRing="clr-namespace:AvaloniaProgressRing;assembly=AvaloniaProgressRing"
              x:DataType="vm:MainViewModel">
+  <UserControl.Resources>
+    <helpers:DateFormatConverter x:Key="DateFormatter" />
+  </UserControl.Resources>
   <Grid ColumnDefinitions="*"
         RowDefinitions="Auto, 2*, Auto, Auto, *">
     <Button Command="{Binding ShowSettings}"
@@ -136,10 +139,16 @@
                                     Width="125">
                 <DataGridTemplateColumn.CellTemplate>
                     <DataTemplate>
-                        <Label Content="{Binding ReceiptDate}" 
-                               VerticalAlignment="Center"
+                        <Label VerticalAlignment="Center"
                                Margin="8,0,8,0"
-                               HorizontalAlignment="Left"/>
+                               HorizontalAlignment="Left">
+                               <Label.Content>
+                                    <MultiBinding Converter="{StaticResource DateFormatter}">
+                                        <Binding Path="ReceiptDate" />
+                                        <Binding Path="$parent[UserControl].((vm:MainViewModel)DataContext).DataGridDateFormat" />
+                                    </MultiBinding>
+                               </Label.Content>
+                        </Label>
                     </DataTemplate>
                 </DataGridTemplateColumn.CellTemplate>
                 <DataGridTemplateColumn.CellEditingTemplate>