CODEWITHSUNDEEP
mauiobservablecollection
ErnestJ
ErnestJ

Reputation: 235

Maui ObservableCollection not updating UI when adding new item

I'm using CommunityToolkit.Mvvm and having some issues with ObservableCollection. I've some view model declared like this:

public partial class LabourListViewModel: ObservableObject
{
    [ObservableProperty] 
    private ObservableCollection<LabourJson> _labourList = [];

    [RelayCommand]
    public void LabourAdded( LabourJson labour )
    {
        LabourList.Insert( 0, labour );
    }
}

Problem is that when method LabourAdded is called, UI doesn't update. I thought that ObservableProperty should observe changes and update UI accordingly?

If after insert I do like below then UI is updated, but why do I need to recreate list every time?

LabourList = new ObservableCollection<LabourJson>( LabourList.ToList() );

Upvotes: 0

Views: 76

Answers (1)

Stephen Quan
Stephen Quan

Reputation: 26179

Your ObservableCollection should be defined as follows:

ObservableCollection<LabourJson> LabourList { get; } = new ObservableCollection<LabourJson> LabourList

It is unnecessary to apply the [ObservableProperty] attribute since your UI need not rely on the PropertyChanged notification. Similarly, it is not recommended to provide a setter. The ObservableCollection is initialized once by the initializer, and from this point onwards, it will broadcast CollectionChanged events whenever you add, update, or delete from the collection.

Typically, consumers of such collections (e.g. ListView and CollectionView) are designed to listen for CollectionChanged events to update their UI.

Upvotes: 2

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