How to initialize a field in view model if I need to call the suspend function to get the value?

I a have suspend function that returns value from a database.

suspend fun fetchProduct(): Product

When I create the view model I have to get product in this field

private val selectedProduct: Product 

I tried doing it this way but it doesn't work because I'm calling this method outside of the coroutines

private val selectedProduct: Product = repository.fetchProduct()

CodePudding user response：

You need to run the function inside a coroutine scope to get the value.

if you're in a ViewModel() class you can safely use the viewModelScope

private lateinit var selectedProduct:Product

fun initialize(){
    viewModelScope.launch {
        selectedProduct = repository.fetchProduct()
    }
}

CodePudding user response：

Since fetchProduct() is a suspend function, you have to invoke it inside a coroutine scope.

For you case I would suggest the following options:

1. Define selectedProduct as nullable and initialize it inside your ViewModel as null:

class AnyViewModel : ViewModel {

    private val selectedProduct: Product? = null
    

    init {
        viewModelScope.launch {
            selectedProduct = repository.fetchProduct()
        }
    }
}

2. Define selectedProduct as a lateinit var and do the same as above;

Personally I prefer the first cause I feel I have more control over the fact that the variable is defined or not.