Question

I need to execute async delete operation with user confirmation. Something like this:

public ReactiveAsyncCommand DeleteCommand { get; protected set; }
...
DeleteCommand = new ReactiveAsyncCommand();
DeleteCommand.RegisterAsyncAction(DeleteEntity);

...

private void DeleteEntity(object obj)
{
    if (MessageBox.Show("Do you really want to delete this entity?", "Confirm", MessageBoxButton.YesNo) == MessageBoxResult.Yes)
    {
        //some delete operations
    }
}

The problem is the MessageBox would execute asynchronously too.
Which is the best pattern in ReactiveUI to ask user synchronously and then execute method asynchronously?

Answer 1

The most straightforward way to do this is to just use two commands:

public ReactiveCommand DeleteCommand { get; protected set; }
private ReactiveAsyncCommand ExecuteDelete { get; protected set; }

/*
 * In the Constructor
 */

ExecuteDelete = new ReactiveAsyncCommand();
ExecuteDelete.RegisterAsyncAction(() => /* Do the delete */);

DeleteCommand = new ReactiveCommand(ExecuteDelete.CanExecuteObservable);
DeleteCommand
    .Where(_ => MessageBox.Show("Delete?") == MessageBoxResult.Yes)
    .InvokeCommand(ExecuteDelete);