Comments on: Rules of MVVM?? http://michaelsync.net/2010/02/03/rules-of-mvvm Sharing our knowledge Thu, 19 Jan 2012 06:22:49 +0000 hourly 1 http://wordpress.org/?v= By: Marvin Varela http://michaelsync.net/2010/02/03/rules-of-mvvm/comment-page-1#comment-211373 Marvin Varela Fri, 05 Feb 2010 18:00:55 +0000 http://michaelsync.net/?p=1531#comment-211373 I agree with Michael about the ObservableCollection approach; however, I would like to point out that some times it is necessary to add some other ingredients for the mix, for example, creating a custom ItemsControl class that prepares the container or even returns a custom one. Similarly, sometimes it is necessary to watch out for timing: binding immediately may not be a good idea as it all happens in the UI thread, you may want to create a mechanism that delays the actual binding until after a fancy animation is over. If testability is key, you really want to make the separation clear and strict. I agree with Michael about the ObservableCollection approach; however, I would like to point out that some times it is necessary to add some other ingredients for the mix, for example, creating a custom ItemsControl class that prepares the container or even returns a custom one. Similarly, sometimes it is necessary to watch out for timing: binding immediately may not be a good idea as it all happens in the UI thread, you may want to create a mechanism that delays the actual binding until after a fancy animation is over.

If testability is key, you really want to make the separation clear and strict.

]]> By: Will Rogers http://michaelsync.net/2010/02/03/rules-of-mvvm/comment-page-1#comment-211279 Will Rogers Thu, 04 Feb 2010 15:57:13 +0000 http://michaelsync.net/?p=1531#comment-211279 Thanks Michael. I think I understand your suggestion and will give it a shot in the near future. I'll try to remember to post back here with my results. Thanks Michael. I think I understand your suggestion and will give it a shot in the near future. I’ll try to remember to post back here with my results.

]]> By: Michael Sync http://michaelsync.net/2010/02/03/rules-of-mvvm/comment-page-1#comment-211278 Michael Sync Thu, 04 Feb 2010 15:53:07 +0000 http://michaelsync.net/?p=1531#comment-211278 You can probably use the Data Template for that. Put those controls in DT. Let's say you have a class called Circle. So, you can have the ObservableCollection[Circle] in VM. You have ItemControl in V and that is binded to that OC[Circle]... If you want to increase one circle, then you can just add new circle to OC.. then new circle control from DT will be displayed in View. Feel free to let me know if you are not clear with that. You can probably use the Data Template for that. Put those controls in DT.

Let’s say you have a class called Circle. So, you can have the ObservableCollection[Circle] in VM. You have ItemControl in V and that is binded to that OC[Circle]…

If you want to increase one circle, then you can just add new circle to OC.. then new circle control from DT will be displayed in View.

Feel free to let me know if you are not clear with that.

]]> By: Will Rogers http://michaelsync.net/2010/02/03/rules-of-mvvm/comment-page-1#comment-211277 Will Rogers Thu, 04 Feb 2010 15:46:55 +0000 http://michaelsync.net/?p=1531#comment-211277 The rule I've been struggling with most is not keeping a reference to the View in the ViewModel. For instance, I have an operation whose result requires me to add additional XAML controls to the View. I haven't figured out how to do this without directly using the View from the ViewModel. Any suggestions? This is a Silverlight 3 application. The rule I’ve been struggling with most is not keeping a reference to the View in the ViewModel. For instance, I have an operation whose result requires me to add additional XAML controls to the View. I haven’t figured out how to do this without directly using the View from the ViewModel.

Any suggestions? This is a Silverlight 3 application.

]]>