WPF DataGrid - Combining TimeSeries with MultiBinding, will lose notification of a change. What for?

Question

I have a class that has two ObservableCollection <TimeValue>, where TimeValue is a custom DateTime / Value batch with change notification (via INotifyPropertyChanged). I call these goals and actions.

When I snap them to a diagram, everything works fine, and I get two LineSeries. If I bind one of them to the DataGrid, the Date column and the Value column work fine. I even got the TwoWay binding I need.

However, I need to have a DataGrid that has a Date column and columns for goals and actual data. The problem is that I need to list ALL dates in the range, while some of these dates may not have the corresponding values ​​in Targets, Actuals, or both.

So, I decided that I would make a MultiBinding that takes targets and Actuals as input, and outputs a combined TimeSeriesC with null values ​​when any of the originals doesn't matter.

It works, but does not respond to any changes in the underlying data.

This works fine (binding to a single ObservableCollection):

<ctrls:DataGrid Grid.Row="1" Height="400" AutoGenerateColumns="False" CanUserDeleteRows="False" SelectionUnit="Cell">
<ctrls:DataGrid.ItemsSource>
    <Binding Path="Targets"/>
    <!--<MultiBinding Converter="{StaticResource TargetActualListConverter}">
        <Binding Path="Targets"/>
        <Binding Path="Actuals"/>
    </MultiBinding>-->
</ctrls:DataGrid.ItemsSource>
<ctrls:DataGrid.Columns>
    <ctrls:DataGridTextColumn Header="Date" Binding="{Binding Date,StringFormat={}{0:ddd, MMM d}}"/>
    <ctrls:DataGridTextColumn Header="Target" Binding="{Binding Value}"/>
    <!--<ctrls:DataGridTextColumn Header="Target" Binding="{Binding Value[0]}"/>
    <ctrls:DataGridTextColumn Header="Actual" Binding="{Binding Value[1]}"/>-->
</ctrls:DataGrid.Columns>

This works, but only on the first initialization. No response to change notification:

<ctrls:DataGrid Grid.Row="1" Height="400" AutoGenerateColumns="False" CanUserDeleteRows="False" SelectionUnit="Cell">
<ctrls:DataGrid.ItemsSource>
    <!--<Binding Path="Targets"/>-->
    <MultiBinding Converter="{StaticResource TargetActualListConverter}">
        <Binding Path="Targets"/>
        <Binding Path="Actuals"/>
    </MultiBinding>
</ctrls:DataGrid.ItemsSource>
<ctrls:DataGrid.Columns>
    <ctrls:DataGridTextColumn Header="Date" Binding="{Binding Date,StringFormat={}{0:ddd, MMM d}}"/>
    <!--<ctrls:DataGridTextColumn Header="Target" Binding="{Binding Value}"/>-->
    <ctrls:DataGridTextColumn Header="Target" Binding="{Binding Value[0]}"/>
    <ctrls:DataGridTextColumn Header="Actual" Binding="{Binding Value[1]}"/>
</ctrls:DataGrid.Columns>

And here is my IMultiValueConverter:

class TargetActualListConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        TimeSeries<double> Targets = values[0] as TimeSeries<double>;
        TimeSeries<double> Actuals = values[1] as TimeSeries<double>;
        DateTime[] range = TimeSeries<double>.GetDateRange(Targets, Actuals);//Get min and max Dates
        int count = (range[1] - range[0]).Days;//total number of days
        DateTime currDate = new DateTime();
        TimeSeries<double?[]> combined = new TimeSeries<double?[]>();
        for (int i = 0; i < count; i++)
        {
            currDate = range[0].AddDays(i);
            double?[] vals = { Targets.Dates.Contains(currDate) ? (double?)Targets.GetValueByDate(currDate) : null, Actuals.Dates.Contains(currDate) ? (double?)Actuals.GetValueByDate(currDate) : null };
            combined.Add(new TimeValue<double?[]>(currDate, vals));
        }
        return combined;
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
    {
        TimeSeries<double?[]> combined = value as TimeSeries<double?[]>;
        TimeSeries<double> Targets = new TimeSeries<double>();
        TimeSeries<double> Actuals = new TimeSeries<double>();

        foreach (TimeValue<double?[]> tv in combined)
        {
            if(tv.Value[0]!=null)
                Targets.Add(new TimeValue<double>(tv.Date,(double)tv.Value[0]));
            if (tv.Value[1] != null)
                Actuals.Add(new TimeValue<double>(tv.Date, (double)tv.Value[1]));
        }
        TimeSeries<double>[] result = { Targets, Actuals };
        return result;

    }
}

I cannot be too far away as it displays values.

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!

Answer 1

, . ObservableCollection INotifyCollectionChanged, (Add/Remove/Replace/Move/ Reset). , , , , , INotifyPropertyChanged. MultiCoverter , , .

, , - CompositeCollection Element , .

, ItemsSource , - :

<ctrls:DataGrid.ItemsSource>
    <CompositeCollection>
            <CollectionContainer Collection="{Binding Targets}" />
            <CollectionContainer Collection="{Binding Actuals}" />
       </CompositeCollection>
</ctrls:DataGrid.ItemsSource>

( , " - " , , , , . )

, , , Target Actual. ObservableCollection. ValueConverter CompositeCollection. , . , , . CompositeCollection, , // .., , .

WPF ViewModel, M-V-VM. , , INotifyPropertyChanged IDataErrorInfo, , .

, , Name INotifyPropertyChanged, .

public partial class Window1 : Window
{
    public Window1()
    {
        InitializeComponent();

        Foo foo1 = new Foo { ID = 1, Name = "Foo1" };
        Foo foo3 = new Foo { ID = 3, Name = "Foo3" };
        Foo foo5 = new Foo { ID = 5, Name = "Foo5" };
        Bar bar1 = new Bar { ID = 1, Name = "Bar1" };
        Bar bar2 = new Bar { ID = 2, Name = "Bar2" };
        Bar bar4 = new Bar { ID = 4, Name = "Bar4" };

        ObservableCollection<FooBarViewModel> fooBar = new ObservableCollection<FooBarViewModel>();
        fooBar.Add(new FooBarViewModel(foo1, bar1));
        fooBar.Add(new FooBarViewModel(bar2));
        fooBar.Add(new FooBarViewModel(foo3));
        fooBar.Add(new FooBarViewModel(bar4));
        fooBar.Add(new FooBarViewModel(foo5));

        this.DataContext = fooBar;
    }
}

public class Foo
{
    public int ID { get; set; }
    public string Name { get; set; }
}

public class Bar
{
    public int ID { get; set; }
    public string Name { get; set; }
}

public class FooBarViewModel : INotifyPropertyChanged
{
    public Foo WrappedFoo { get; private set; }
    public Bar WrappedBar { get; private set; }

    public int ID
    {
        get
        {
            if (WrappedFoo != null)
            { return WrappedFoo.ID; }
            else if (WrappedBar != null)
            { return WrappedBar.ID; }
            else
            { return -1; }
        }
        set
        {
            if (WrappedFoo != null)
            { WrappedFoo.ID = value; }
            if (WrappedBar != null)
            { WrappedBar.ID = value; }

            this.NotifyPropertyChanged("ID");
        }
    }

    public string BarName
    {
        get
        {
            return WrappedBar.Name;
        }
        set
        {
            WrappedBar.Name = value;
            this.NotifyPropertyChanged("BarName");
        }
    }

    public string FooName
    {
        get
        {
            return WrappedFoo.Name;
        }
        set
        {
            WrappedFoo.Name = value;
            this.NotifyPropertyChanged("FooName");
        }
    }

    public FooBarViewModel(Foo foo)
        : this(foo, null) { }
    public FooBarViewModel(Bar bar)
        : this(null, bar) { }
    public FooBarViewModel(Foo foo, Bar bar)
    {
        WrappedFoo = foo;
        WrappedBar = bar;
    }

    public event PropertyChangedEventHandler PropertyChanged;

    private void NotifyPropertyChanged(String info)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(info));
        }
    }
}

:

 <ListView ItemsSource="{Binding}">
    <ListView.View>
        <GridView>
            <GridViewColumn Header="ID" DisplayMemberBinding="{Binding ID}"/>
            <GridViewColumn Header="Foo Name" DisplayMemberBinding="{Binding FooName}"/>
            <GridViewColumn Header="Bar Name" DisplayMemberBinding="{Binding BarName}"/>
        </GridView>
    </ListView.View>
</ListView>