Request for additional ViewModelBase<T> changes

Jack posted on Thursday, April 29, 2010

Not sure if this already came up but could we add virtual OnModelXyz methods for all the attached events in OnModelChanged. 

If I want to do any processing based on those then I have to basically replicate OnModelChanged and then pay attention to any future changes.

Thanks

jack

JonnyBee replied on Friday, April 30, 2010

Hi Jack ,

See this issue: http://www.lhotka.net/cslabugs/edit_bug.aspx?id=730  

Checked in 2 days ago and available in CSLA 4 repository.

If you have time - you can download the latest version from repository and try out.

Jack replied on Friday, April 30, 2010

Those were the changes I thought I had seen mentioned before.  However what I was looking for was some of the other private methods.  I overrode OnModelChanged so that I could attach/detach from the same events to expose the private methods.  It would be nice to not have to attach/detach from the same events over and over.

I posed my override of OnModelChanged.  Mostly I'm looking to trap changes to certain properites in my ViewModel so I can do something to the UI.

Jack

protected override void OnModelChanged(T oldValue, T newValue)

{

base.OnModelChanged(oldValue, newValue);

 

if (ReferenceEquals(oldValue, newValue)) return;

// unhook events from old value

if (oldValue != null)

{

var npc = oldValue as INotifyPropertyChanged;

if (npc != null)

npc.PropertyChanged -= Model_PropertyChanged;

var ncc = oldValue as INotifyChildChanged;

if (ncc != null)

ncc.ChildChanged -= Model_ChildChanged;

var nb = oldValue as INotifyBusy;

if (nb != null)

nb.BusyChanged -= Model_BusyChanged;

}

// hook events on new value

if (newValue != null)

{

var npc = newValue as INotifyPropertyChanged;

if (npc != null)

npc.PropertyChanged += Model_PropertyChanged;

var ncc = newValue as INotifyChildChanged;

if (ncc != null)

ncc.ChildChanged += Model_ChildChanged;

var nb = newValue as INotifyBusy;

if (nb != null)

nb.BusyChanged += Model_BusyChanged;

}

OnViewModelChanged(EventArgs.Empty);

}

protected virtual void Model_BusyChanged(object sender, BusyChangedEventArgs e){}

protected virtual void Model_PropertyChanged(object sender, PropertyChangedEventArgs e) {}

protected virtual void Model_ChildChanged(object sender, ChildChangedEventArgs e){}