mvvm - prismv2 - INotifyPropertyChanged
- by depictureboy
Since this is so long and prolapsed and really doesnt ask a coherent question:
1: what is the proper way to implement subproperties of a primary object in a viewmodel?
2: Has anyone found a way to fix the delegatecommand.RaiseCanExecuteChanged issue? or do I need to fix it myself until MS does?
For the rest of the story...continue on.
In my viewmodel i have a doctor object property that is tied to my Model.Doctor, which is an EF POCO object. I have onPropertyChanged("Doctor") in the setter as such:
Private Property Doctor() As Model.Doctor
Get
Return _objDoctor
End Get
Set(ByVal Value As Model.Doctor)
_objDoctor = Value
OnPropertyChanged("Doctor")
End Set
End Property
The only time OnPropertyChanged fires if the WHOLE object changes. This wouldnt be a problem except that I need to know when the properties of doctor changes, so that I can enable other controls on my form(save button for example). I have tried to implement it in this way:
Public Property FirstName() As String
Get
Return _objDoctor.FirstName
End Get
Set(ByVal Value As String)
_objDoctor.FirstName = Value
OnPropertyChanged("Doctor")
End Set
End Property
this is taken from the XAMLPowerToys controls from Karl Shifflet, so i have to assume that its correct. But for the life of me I cant get it to work.
I have included PRISM in here because I am using a unity container to instantiate my view and it IS a singleton. I am getting change notification to the viewmodel via eventaggregator that then populates Doctor with the new value. The reason I am doing all this is because of PRISM's DelegateCommand. So maybe that is my real issue.
It appears that there is a bug in DelegateCommand that does not fire the RaiseCanExecuteChanged method on the commands that implement it and therefore needs to be fired manually. I have the code for that in my onPropertyChangedEventHandler. Of course this isnt implemented through the ICommand interface either so I have to break and make my properties DelegateCommand(of X) so that I have access to RaiseCanExecuteChanged of each command.
