In the MVVM architecture, where does one start an activity for result ? For example, I need to get banking informations from an nfc tag in my payment app. What I do is I start the ReadNFCActivity from my PaymentActivity, retrieve the results there, and then I call my PaymentViewModel's updatePaymentInformations(name: String, account_number: Int...) method from my PaymentActivity. The data going from one activity to the other before being sent to the viewModel doesn't feel like the right way. How would you structure this ?

Any help will be appreciated !

CodePudding user response：

In MVVV you shouldn't gather or keep data in your views. In your example you shouldn't get data from the card in the view. You can get the data from the card in the viewmodel and save in a Livedata variable. Whenever you need to display the data you can observe this Livedata. Handling the data this way can help you in complicate lifecycle aware data management scenarios.

CodePudding user response：

Its better to think of Activities as containing a view not the view itself. Meaning showing stuff on the screen is not it's only purpose it is also a/the context of the app which allows access to OS functionality and resources.

Unlike Windows where you can access OS functionality and resources anywhere making MVVM trivial, instead in Android you have to access it through a context, which is the Activity/Application.

IMO

If your activity is starting another activity for a result than its well with its right to do that, because its the context. Passing that result to the view model is no different than sending input from a listener to the view model like text input.

If the view model isn't touch the views than you view model is good to go.