Can I manually create ViewModels instead of Prism?

[achobanov]

Essentially, I need to manage the reference to a ViewModel, before I navigate to it's view. Is this possible?

[sigmarsson]

Just inject it whenever you need those references.
i needed something similar earlier.
#2496

[achobanov]

@sigmarsson thanks for the response, but I'm trying to do something different. I have structed my views in a tree. Meaning that I have a root view and beneath it are nodes of parents and children. I've designed it like that because part of my requirements is that I am able to represent the data for all child views within the current parent view.

Let say that I have nodes A, B and C.

1. A has a list of B nodes
2. B has a single C node

Each node is an instance of it's view. There are multiple instances of all nodes, aka multiple views of the same type:

At the level of node B I have to render B-specific content and C-specific content. And up one level - on A I need A-specific content and a list of B aggregates, each showing some data from B and C.

In order to achieve that I'm tracking every child VIewModels in a collection in their parent, up until the root ViewModel. The models are mapped from data as it comes in the data layer. However when I navigate to a new View instance, Prism creates it's own instance of a ViewModel instead of using mine directly. My current approach is to map the former from the latter, but I end up with two objects, rather than one. That causes problems, as you might imagine.

Ideally I would be able to instantiate my own ViewModel, add it to a collection and pass that same object to Prism to render. Then due to reference equality, my data structure state will represent the actual state from the ViewModel.

[brianlagunas]

If you want to stop prism from automatically creating the ViewModel just set the AutowireViewModel attached property to false on the view.

[mxsoftware]

One possible approach is to use ViewModelLocationProvider.SetDefaultViewModelFactory
to define your own view model creation strategies.