Is there a common navigation convention in an MVVM Light Windows Phone application?

Question

As my app gets bigger I am finding that the same type of entity is appearing more and more throughout, typically in a listbox.

When someone taps on the entity, I want to navigate to the detailed view of this entity.

An example of this would be a product: it appears in a product list by category, it appears in search results, or it might appear as a saved favourite. In my instance, all of these would come from a table in local SQLCE storage.

Every time I surface the entity in some way that someone could tap on it, I basically cut the same code: subscribe to the SelectionChange event on the listbox, extract the entity, use MVVM Light messaging to signal that the selected entity has changed, then call NavigationService to do its business.

Has anyone worked on something similar and, if so, what have you came up with? Or more importantly, if there's some MVVM Light toolkit convention that I'm overlooking, could you please point me in the right direction?

Answer 1

Are you calling the NavigationService from code-behind or the View Model now? If the former, you could check the WP7 Navigation arcticle by LBugnion for triggering it from the VM. If you combine that with the EventToCommand behavior (like in here) you should be able to create a nice and clean "MyEntitySelected" command in the VM which takes the entity as a parameter.

Answer 2

I think the question here is, how do I deal with this without cut/paste the same code each time? If this is the case, maybe trying to package the entity/listbox thing in a XAML usercontrol! Take a look at this: http://www.windowsphonegeek.com/articles/Creating-a-WP7-Custom-Control-in-7-Steps

Then if the representation needs to be different, you could have a look at this: http://www.windowsphonegeek.com/articles/Implementing-Windows-Phone-7-DataTemplateSelector-and-CustomDataTemplateSelector ( this example does different styling in one listbox, but you can change this to only apply different style on each different page with a listbox on it )