CODEWITHSUNDEEP
c#wpfxamlinheritancebinding
Juan Salvador Portugal
Juan Salvador Portugal

Reputation: 1319

How to bind class that inherit from collection wpf

i'm pretty new in wpf and i'm having troubles with a simple ListBox binding.

This is the case, i have two clases

public class Child, ImplementedPropertyChanged
{
    private string _name;
    public string Name 
    { 
        get => _name;
        set
        {
            _name = value;
            OnPropertyChanged();
        }
    }
}

public class ChildCollection : IObservableCollection<Child>
{
    new public void Add(Child child)
    {
        //some logic
        base.Add(child);
    }
}

And i'm trying to bind it in xaml

<Window x:Class="GeneradorDeCarpetaPlanos.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:GeneradorDeCarpetaPlanos"
        xmlns:VM="clr-namespace:GeneradorDeCarpetaPlanos.ViewModel"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
        <Window.DataContext>
            <VM:ChildCollection></VM:ChildCollection>
        </Window.DataContext>

    <StackPanel>

        <ListBox ItemsSource="{Binding}">
            <ListBoxItem>
                <TextBlock Text="{Binding Path=Name}"></TextBlock>
            </ListBoxItem>
        </ListBox>       

    </StackPanel>
</Window>

And in the code behind 

ChildCollection childs = null;
    public MainWindow()
    {
        childs = new ChildCollection();            
        InitializeComponent();
        DataContext = childs;
    }

I try to bind the Count property to a simple TextBlock and that is showing the Count but not updating with ChildCollection object

How shoud i bind it?

Thanks!

Upvotes: 0

Views: 281

Answers (2)

Clemens
Clemens

Reputation: 128077

The problem is that you explicitly add a ListBoxItem to the ListBox.

You probably wanted to define the ItemTemplate instead:

<ListBox ItemsSource="{Binding}">
    <ListBox.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding Name}"/>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

You should also consider using an ObservableCollection instead of creating your own collection class:

private readonly ObservableCollection<Child> children = new ObservableCollection<Child>();

public MainWindow()
{
    InitializeComponent();
    DataContext = children;
}

Upvotes: 2

rychlmoj
rychlmoj

Reputation: 455

I think the problem is in iappropriate definition of the cobservable collection. Anyway for the learning scenario try to use the standard predefined System.ObservableCollection<> instead. The collection also have to be initialized (not nbe null) in that little experiment...

So in your case, please try as the follows: 

ObservablledCollection<Child> childs = new ObservableCollection<Child>;

public MainWindow()
{
    InitializeComponent();
    DataContext = childs;
}

Upvotes: 0

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