如何智能地创建和调试嵌套堆栈布局的复杂 Maui 数据绑定？

Question

我一直在尝试创建一个数据绑定来访问父堆栈布局中的值。

我创建了一个转换器，认为这可以让我了解我的绑定在做什么。

但是，我只是得到一个空参数值——我需要设置为父堆栈布局中字段的文本值？

有 .. 必须 .. 一些技术来智能调试绑定并了解如何创建正确的绑定？

我已经尝试创建一个标签来给我一些关于绑定正在做什么的线索 - 尝试了以下标签的许多变体但是..我收效甚微？

<Label Text="{Binding Source={x:Reference parentView}, StringFormat='{0}'}" />

这是我的转换器，其中参数始终是 mull.

// changing ConverterParameter={Binding CustId}}">  to ConverterParameter={Binding InvHeader.CustId}}">
// just changes the PATH in parameter to PATH InvHeader.CustId
// we are always passing null??
// value shows as 39 InvItems
// trying a few variations, all of them return null in parameter
// <StackLayout BindableLayout.ItemsSource="{Binding InvItems, Converter={StaticResource InvItemsForCustIdConverter}, ConverterParameter={Binding InvHeader.CustId}}">
// <StackLayout BindableLayout.ItemsSource="{Binding InvItems, Converter={StaticResource InvItemsForCustIdConverter}, ConverterParameter={Binding CustId}}">
// <StackLayout BindableLayout.ItemsSource="{Binding InvItems, Converter={StaticResource InvItemsForCustIdConverter}, ConverterParameter={Binding CustId, Source={x:Reference parentView}, Path=InvHeader}}">

public class InvItemsForCustIdConverter : IValueConverter
{
  public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
  {
      return value; // If I return the invItems then the display works, but does not Limit the InvItems to those matching the InvHeader StackLayout

      if (value is List<InvItem> invItems && parameter is string custId)
      {
          return invItems.Where(x => x.CustId == custId).ToList();
      }
      return null;
  }

  public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
  {
      throw new NotImplementedException();
  }
}

这是我正在尝试调试的嵌套 XAML

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage x:Name="parentView"
             xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:converters="clr-namespace:MauiClient"
             x:Class="MauiClient.Invoice"
             Title="Invoice">
    <ContentPage.Resources>
        <ResourceDictionary>
            <converters:InvItemsForCustIdConverter x:Key="InvItemsForCustIdConverter" />
        </ResourceDictionary>
    </ContentPage.Resources>

    <ScrollView>
        <StackLayout>
            <!-- Header section -->
            <Label Text="Hospitals" FontSize="Title" />
            <CollectionView ItemsSource="{Binding invHeaders}" BackgroundColor="Blue">
                <CollectionView.ItemTemplate>
                    <DataTemplate>
                        <StackLayout>
                            <Label Text="{Binding Company}" />
                            <Label Text="{Binding Addr1}" />
                            <Label Text="{Binding Phone}" />
                            <Label Text="{Binding CustId}" BackgroundColor="Red"  TextColor="White" />
                            <!-- Invoice items section -->
                            <Label Text="Tech Times" FontSize="Title" BackgroundColor="Yellow" TextColor="Black"/>
                            <StackLayout BindingContext="{Binding BindingContext, Source={x:Reference parentView}}" BackgroundColor="Green">
                                <StackLayout BindableLayout.ItemsSource="{Binding InvItems, Converter={StaticResource InvItemsForCustIdConverter}, ConverterParameter={Binding CustId}}">
                                    <BindableLayout.ItemTemplate>
                                        <DataTemplate>
                                            <StackLayout Orientation="Horizontal" Spacing="20">
                                                <Label Text="{Binding ItemId}" />
                                                <Label Text="{Binding CustId}" BackgroundColor="Red"  TextColor="White" />
                                                <Label Text="{Binding Source={x:Reference parentView}, StringFormat='{0}'}" />
                                            </StackLayout>
                                        </DataTemplate>
                                    </BindableLayout.ItemTemplate>
                                </StackLayout>
                            </StackLayout>
                        </StackLayout>
                    </DataTemplate>
                </CollectionView.ItemTemplate>
            </CollectionView>
        </StackLayout>
    </ScrollView>
</ContentPage>

这是基本的 ViewModel：

public class InvoiceViewModel  {
        public List<InvHeader> InvHeaders { get; set; }
        public List<InvItem> InvItems { get; set; }
}