Android kotlin 使用 ViewModelFactory 将动态参数/参数传递给 ViewModel

Question

To transfer additional arguments/parameters for ViewModel we used ViewModelFactory. For example

ExtraParamsViewModelFactory(this.requireActivity().application, "some string value")

But when the ViewModel is created, I can't change the arguments/parameters dynamically

 val myViewModel = ViewModelProvider(this, ExtraParamsViewModelFactory(this.requireActivity().application, "some string value")).get(SomeViewModel::class.java)

"some string value" becomes harcoded in fragment/activity class. In "some string value" I need to pass a date that is always different to ViewModel. In the fragment, the user selected a date, clicked on the button and this date as a arguments/parameters pass to ViewModel. Not suitable for this ViewModelFactory?

Answer 1

No need to pass arguments in ViewModel constructor. all what you need is a is a setter & warrper class depending on your use.

I guess your ViewModel will have some thing like this

data class CustomWrapper<T>(var value:T)
class  VM : ViewModel(){

    private val stringValue = CustomWrapper<String>("")

    fun setNewStringValue(value:String){
        stringValue.value = value
        //TODO:: update stuff related to `stringValue` 
    }

}

then in your Activity/Fragment..simply call it..like this

vm.setNewStringValue("new value")