What I want to achieve. A navigation service for MVVM Light WPF where I can easily say NavigateTo(View URI or ViewModel and a string name of the framework element that should present the View or ViewModel).
I first tried the View First approach from here. https://stackoverflow.com/a/28968560/5272185
Problems I found with it was that the Frame frameworkelement seems to run sandboxed, and even though I set the view's datacontext to bind to a viewmodel retrieved from my viewmodellocator I seem to get a different instance inside the Frame. Also styles seem not to be inherit down into the Frame and the MVVM Light Messenger's messages do not seem to bubble up from the View shown inside a Frame.
Also the code to find the Frame element failes if the Frame is located within a ViewBox. I have no clue why but if I just remove the ViewBox it finds it correctly.
I ignored the ViewBox issue (removed the ViewBox) and changed the NavigationService to store ViewModelBase types instead of URI, and I changed the code to find a FrameworkElement of type ContentControl instead of Frame, set the ContentControl's content instead of a Frame's source. This so I should not run into the sandbox problem. This worked, but I now have no good way of switching to a detail view (using the same ViewModel as datacontext for multiple views).
Questions
When using a ViewModel first NavigationService as explained above, is there an easy way to show a detail view (sharing a ViewModel) without code duplication?
In case of a View first navigationservice exactly like the code in the link. Is there a way to make the Frame inherit the correct datacontext and styles (not running sandboxed at all)?
Can someone explain why the VisualTreeHelper code in the provided link does not find a framework element if the element is inside a ViewBox?
I should also mention that I have tried the approach to make a CurrentVM property and CurrentDetailMode property on the ViewModel and bind a ContentControl's content to the CurrentVM property and used DataTemplates with DataTriggers (bind to CurrentDetailMode) to set the corresponding View(s) to the ViewModels. According to this post. https://rachel53461.wordpress.com/2011/12/18/navigation-with-mvvm-2/
It works well and supports detail views. My goal with the navigationservice is that I want to add all views or viewmodels to the service in one place. Not having to create the CurrentVM and CurrentDetailMode properties on every ViewModel that should be able to show different content / views. And I would prefer an easier solution than manually setting up Datatemplates with special DataTriggers for supporting "Detail" views. Also the navigation service discussed has a history queue so one can go back.
I managed to solve / answer my own questions
Just create a dumb ViewModel class for the Detail view, provide it with the (Main)ViewModel instance and make that ViewModel instance a property so you can bind to it. Done! Easy after all, and with Dependency injection it can become a breath.
See this link page.DataContext not inherited from parent Frame?
I solved this one and tracked it in the following separate question. See answer here WPF ViewBox blocks VisualTreeHelper search