Best Practice for handling collection updates in .net-maui (MVVM) - mvvm

Question

I have been working with MVVM and ObservableCollections for some time now, but it is still not clear to me what is the best practice for handling an update of a collection. When I add an item to the collection the UI gets notified and shows the new item in e.g. a ListView.
But I cannot see how this process works for the update of an item in the Collection. What I do now is to completely re-assign the collection and raise an OnPropertyChanged event but this updates the whole collection which seems like overkill and not really efficient.
Example use-case: The user edits an item and I want the change to be presented in the List or the Collection receives an update from a different service like a SignalR message.
I tried to assign new Values to an item of the ObservableCollection but it seems not to update the View even if I raise the OnPropertyChanged Event

Answer 1

From document From Data Bindings to MVVM,we could know that:
ViewModels generally implement the INotifyPropertyChanged interface,
which means that the class fires a PropertyChanged event whenever one
of its properties changes. The data binding mechanism in Xamarin.Forms
attaches a handler to this PropertyChanged event so it can be notified
when a property changes and keep the target updated with the new
value.
So if you want the UI updates automatically once changing the value of the property of the Item model in your List, you can implement interface INotifyPropertyChanged for your item model.
You can refer to the following code:
public class Item: INotifyPropertyChanged
{
private string _numType;
public string NumType
{
get => _numType;
set
{
SetProperty(ref _numType, value);
}
}
public string Name { get; set; }
bool SetProperty<T>(ref T storage, T value, [CallerMemberName] string propertyName = null)
{
if (Object.Equals(storage, value))
return false;
storage = value;
OnPropertyChanged(propertyName);
return true;
}
protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public event PropertyChangedEventHandler PropertyChanged;
}
Note:
1.Suppose you want to update UI automatically while modifying the value of NumType,you can add following code:
private string _numType;
public string NumType
{
get => _numType;
set
{
SetProperty(ref _numType, value);
}
}
2.If you want UI update automatically after adding or remove item from your datalist, you just define your list as follows:
public ObservableCollection<ItemModel> Items { get; set; }
For more information, check ObservableCollection Class.