CODEWITHSUNDEEP
navigationwindows-phone-8.1caliburn.micro
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Reputation: 1921

Caliburn.Micro & Windows Phone 8.1: How to pass parameters to the navigation GoBack() method?

I have a WP 8.1 (native) app and I'm using Caliburn. Micro. In the MainPageViewModel I navigate to the another page, where I want to set some value to the MyObject (property on the MainPageViewModel) and push it back to the MainPageViewModel.

So I navigate to the new page with passing myObject (it's working ok):

navigationService.NavigateToViewModel<AnotherPageViewModel>(myObject)

In the AnotherPageViewModel I set some values to the myObject and I return back to the MainPageViewModel:

navigationService.GoBack();

But how can I pass the changed myObject back to the MainPageViewModel? When I get back, the new instance of myObject in the MainPageViewModel is created.

EDIT: I'd expect that the "changed" myObject will hold the changed values back in the MainPageViewModel after calling GoBack() method, but obviously a new instance is created.

Thanks

Upvotes: 1

Views: 209

Answers (1)

Igor Kulman
Igor Kulman

Reputation: 16361

Two things come to mind.

If you MainPageView does not set NavigationCacheMode to Required then a new instance of MainPageView and MainPageViewModel is created when navigating back. In this case, I would suggest you save the value after selection in AnotherPageViewModel somewhere (settings, etc.) and then load in when MainPageViewModel activates

If you MainPageView sets NavigationCacheMode to Required, then MainPageViewModel is not recreated when navigating back. In this case, I would suggest you use messaging (IEventAggregator). You can send a message to MainPageViewModel informating that the object changed and you may include the whole new object in the message.

Upvotes: 1

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