CODEWITHSUNDEEP
c#wpfmvvmviewmodel
FPGA
FPGA

Reputation: 3865

updating the observable collection of a view model from another helper class

i have a ViewModel with an ObservableCollection, i have a long function that i will use to update the ObservableCollection items however the function is so long and i don't want to put it inside the ViewModel.

i want to do the updates directly on the ObservableCollection so that i can see the changes on my view while the process is running.

i thought about the followig

there will be alot of different functions that will work on this collection, in such cases what is the best programing practice?

Upvotes: 0

Views: 917

Answers (1)

Sandesh
Sandesh

Reputation: 3004

If you are processing the data and then passing the processed data to the View then I think the below option should be one possible solution.

The below solution will process the data while the view is also notified of the change simultaneously.

public class MyViewModel : INotifyPropertyChanged
{
    private ObservableCollection<string> _unprocessedData = new ObservableCollection<string>();
    private ObservableCollection<string> _processedData = new ObservableCollection<string>();
    private static object _lock = new object();
    public event PropertyChangedEventHandler PropertyChanged;

    public ObservableCollection<string> Collection { get { return _processedData; } }//Bind the view to this property

    public MyViewModel()
    {
        //Populate the data in _unprocessedData
        BindingOperations.EnableCollectionSynchronization(_processedData, _lock); //this will ensure the data between the View and VM is not corrupted
        ProcessData();
    }

    private async void ProcessData()
    {
        foreach (var item in _unprocessedData)
        {
            string result = await Task.Run(() => DoSomething(item));
            _processedData.Add(result);
            //NotifyPropertyChanged Collection
        }
    }

    private string DoSomething(string item)
    {
        Thread.Sleep(1000);
        return item;
    }
}

The DoSomething method can be defined in some other class outside the ViewModel.

I hope this helps.

Upvotes: 1

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