C# CommunityToolkit.Mvvm ObservableProperty on a list-CodePudding

I want to try the Community Toolkit 8.0 the MVVM part.

I have a very simple application:

.... 
       d:DataContext="{d:DesignInstance Type=local:MainWindowViewModel}"
.... 
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="12*" />
        </Grid.RowDefinitions>
        <Button x:Name="ButtonDirectory" Grid.Row="0" Grid.Column="0" Margin="50 2 0 2" Width="200" Content="List Directory" Command="{Binding ClickButtonListDirectoryCommand, Mode=OneWay}" />
        <ListView x:Name="ListViewDirectories" Grid.Row="1" Grid.Column="0" ItemsSource="{Binding DirectoriesNames}"  />
    </Grid>

and this is my viewmodel:

public partial class MainWindowViewModel : ObservableObject
{
    [ObservableProperty]
    List<string> _directoriesNames = new();

    [RelayCommand]
    private void ClickButtonListDirectory()
    {
        this.DirectoriesNames.Add("Hello");
    }
}

This construct works, when I use string instead of a list - but obviously I want to use something like a list when my view component is a ListView.

The directoriesNames itself gets updated (saw that in the debugger) but it's not displayed in the view (ListView).

Can someone help me out with that?

Thanks.

CodePudding user response：

Change your List to ObservableCollection.

This code:

[ObservableProperty]
List<string> _directoriesNames = new();

Will notify the UI when the DirectoriesNames itself is changed but the only change you are making to DirectoriesNames is instantiating it.

You can use a ObservableCollection to notify the UI when you add or remove items.

CodePudding user response：

You need to use ObservableCollection :-

ObservableCollection<string> DirectoriesNames = new();