[WPF] XAML how to inherit lists?

Question

Hello everyone!

I have a structure

class MyContainer
{
    List<MyItem> Items;
}

class MyItem
{
    string Name;
    int Value;
}

I want to get instances of Containers whic have values from the base => mean broadcast values to other containers to reduce item definitioan

my imagination

<MyContainer x:Key="DefaultCase">
    <MyItem Name="Four" Value="1"/>
    <MyItem Name="Four" Value="2"/>
</MyContainer>

<MyContainer x:Key="FirstCase" Template="DefaultCase">
    <MyItem Name="Three" Value="3"/>
</MyContainer>

<MyContainer x:Key="SecondCase" Template="DefaultCase">
    <MyItem Name="Four" Value="4"/>
</MyContainer>

To fill containers of List type alike

List<MyItem> DefaultCase
1
2

List<MyItem> FirstCase
1
2
3

List<MyItem> SecondCase
1
2
4

Can somebody help me?

Ofc I know that I can do it from code but I want use xaml for configuration with List type.

Answer 1

Hi, you can write your own "combined list" like in following console demo:

using System;
using System.Collections;
using System.Collections.Generic;

namespace ConsoleApp1
{
  class Program25
  {
    static void Main(string[] args)
    {
      try
      {
        (new Demo()).Execute();
      }
      catch (Exception ex) { Console.WriteLine(ex.ToString()); }
      Console.WriteLine("Continue enter key");
      Console.ReadKey();
    }

    internal class Demo
    {
      internal void Execute()
      {
        List<MyItem> list1 = new List<MyItem>();
        list1.Add(new MyItem() { Name = "Four", Value = 1 });
        list1.Add(new MyItem() { Name = "Four", Value = 2 });

        CombinedList<MyItem> list2 = new CombinedList<MyItem>(list1);
        list2.Add(new MyItem() { Name = "Four", Value = 3 });

        CombinedList<MyItem> list3 = new CombinedList<MyItem>(list1);
        list3.Add(new MyItem() { Name = "Four", Value = 4 });

        Console.WriteLine("--- combined list2");
        foreach (var item in list2) Console.WriteLine($"{item.Name}, Value: {item.Value}");

        Console.WriteLine("--- combined list3");
        foreach (var item in list3) Console.WriteLine($"{item.Name}, Value: {item.Value}");
      }
    }

    public class CombinedList<T> : IList<T>, ICollection<T>, IEnumerable<T>, IEnumerable, IList, ICollection, IReadOnlyList<T>, IReadOnlyCollection<T>
    {
      public CombinedList(List<T> primary)
      {
        externList = primary;
      }

      private List<T> externList;
      private List<T> internList = new List<T>();

      public T this[int index] { get => throw new NotImplementedException(); set => throw new NotImplementedException(); }

      public int Count => throw new NotImplementedException();

      public bool IsReadOnly => throw new NotImplementedException();

      public bool IsFixedSize => throw new NotImplementedException();

      public object SyncRoot => throw new NotImplementedException();

      public bool IsSynchronized => throw new NotImplementedException();

      object IList.this[int index] { get => throw new NotImplementedException(); set => throw new NotImplementedException(); }

      public void Add(T item)
      {
        internList.Add(item);
      }

      public void Clear()
      {
        throw new NotImplementedException();
      }

      public bool Contains(T item)
      {
        throw new NotImplementedException();
      }

      public void CopyTo(T[] array, int arrayIndex)
      {
        throw new NotImplementedException();
      }

      public IEnumerator<T> GetEnumerator()
      {
        return new CombinedEnumerator<T>(externList, internList);
      }

      public int IndexOf(T item)
      {
        throw new NotImplementedException();
      }

      public void Insert(int index, T item)
      {
        throw new NotImplementedException();
      }

      public bool Remove(T item)
      {
        throw new NotImplementedException();
      }

      public void RemoveAt(int index)
      {
        throw new NotImplementedException();
      }

      IEnumerator IEnumerable.GetEnumerator()
      {
        throw new NotImplementedException();
      }

      public int Add(object value)
      {
        throw new NotImplementedException();
      }

      public bool Contains(object value)
      {
        throw new NotImplementedException();
      }

      public int IndexOf(object value)
      {
        throw new NotImplementedException();
      }

      public void Insert(int index, object value)
      {
        throw new NotImplementedException();
      }

      public void Remove(object value)
      {
        throw new NotImplementedException();
      }

      public void CopyTo(Array array, int index)
      {
        throw new NotImplementedException();
      }

      public class CombinedEnumerator<U> : IEnumerator<U>
      {
        public CombinedEnumerator(List<U> externList, List<U> internList)
        {
          this.externList = externList;
          this.internList = internList;
        }

        private List<U> externList;
        private List<U> internList;
        private int i = -1;

        public U Current => (i < externList.Count) ? externList[i] : internList[i - externList.Count];

        object IEnumerator.Current => throw new NotImplementedException();

        public void Dispose() { }

        public bool MoveNext()
        {
          i++;
          return i < internList.Count + externList.Count;
        }

        public void Reset() => i = -1;
      }
    }
    public class MyItem
    {
      public string Name;
      public int Value;
    }
  }
}

Answer 2

Hi FireFenix,

If you only want to use Xaml, merge with CompositeCollection.

<UniformGrid>
    <UniformGrid.Resources>
        <DataTemplate DataType="{x:Type local:MyItem}">
            <TextBlock>
                <Run Text="{Binding Path=Name,Mode=OneWay}" Foreground="Blue"/>
                <Run Text="{Binding Path=Value,Mode=OneWay}" Foreground="Red"/>
            </TextBlock>
        </DataTemplate>
    </UniformGrid.Resources>

    <ListBox x:Name="DefaultCase" >
        <local:MyItem Name="One" Value="1"/>
        <local:MyItem Name="Two" Value="2"/>
    </ListBox>

    <ListBox SelectedItem="{Binding ElementName=DefaultCase,Path=SelectedItem,Mode=TwoWay}">
        <ItemsControl.ItemsSource>
            <CompositeCollection>
                <CollectionContainer Collection="{Binding Path=Items,Source={x:Reference Name=DefaultCase}}"/>
                <CollectionContainer >
                    <CollectionContainer.Collection>
                        <x:Array Type="{x:Type local:MyItem}">
                            <local:MyItem Name="Three" Value="3"/>
                        </x:Array>
                    </CollectionContainer.Collection>
                </CollectionContainer>
            </CompositeCollection>
        </ItemsControl.ItemsSource>
    </ListBox>

</UniformGrid>

Answer 3

If you only want to use Xaml, merge with CompositeCollection.

I saw that class but it's working only for a ItemsSource at container controls.
And it's not working on List datatype :(

Answer 4

Hmm..... Interesting, I'll try.
Thanks.