BindableCollection changes when other ObservableCollection changes - wpf

Question

Is there a way to update an ObservableCollection with the items which are added/deleted in other ObservableCollection?
How can I update my ViewModel's BindableCollection when items are added, removed in FullyObservableCollection?
It is important to note I am trying to use MVVM pattern with Caliburn.Micro.
VieModel
private BindableCollection<Employees> _employees = new BindableCollection(OracleConnector.GetEmployeeRepositorys());
public BindableCollection<Employees> Employees
{
get
{
return _employees;
}
set
{
OracleConnector.List.CollectionChanged += (sender, args) =>
{
_employees = OracleConnector.List;
};
NotifyOfPropertyChange(() => Employees);
}
}
OracleConnector
public class OracleConnector
{
public static FullyObservableCollection<Employees> List = new FullyObservableCollection<Employees>();
public static FullyObservableCollection<Employees> GetEmployeeRepositorys()
{
using (IDbConnection cnn = GetDBConnection("localhost", 1521, "ORCL", "hr", "hr"))
{
var dyParam = new OracleDynamicParameters();
try
{
var output = cnn.Query<Employees>(OracleDynamicParameters.sqlSelect, param: dyParam).AsList();
foreach (Employees employees in output)
{
List.Add(employees);
}
}
catch (OracleException ex)
{
MessageBox.Show("Connection to database is not available.\n" + ex.Message, "Database not available", MessageBoxButton.OK, MessageBoxImage.Error);
}
return List;
}
}
}
I am able to detect if changes are made in the FullyObservableCollection but I don't know how to pass them to the ViewModel.

Answer 1

Use the IEventAggregator in the OracleConnector class when you add a new employee. Publish a EmployeeAddedMessage which contains the new employee. Make sure you publish on the correct thread too. You are likely to need to use PublishOnUiThread method. The ShellViewModel is then able to implement the IHandle<EmployeeAddedMessage> as a method probably called Handle(EmployeeAddedMessage msg). Inside the Handle method you can then add the Employee to the appropriate Employee collection.
You may need to add the OracleConnector to your application bootstrapper as well as the EventAggregator class that Caliburn Micro provide. Your ShellViewModel will also need to call the Subscribe(this) method on the event aggregator. Both the OracleConnector and ShellViewModel need to be using the same instance of the event notifier. So make sure you register the event aggregator as a singleton.
See here for more details about using the event notification. Also, my application here uses event notification for application events.