CODEWITHSUNDEEP
androidmvvm
Bo Z
Bo Z

Reputation: 2607

How to optimize viewmodel?

I got ViewModel that receive one item and it need to update list in the recycler. I made it work but i am wondering if there is a cleaner solution. Im asking about addItem and deleteItem functions

class MainViewModel(private val app: Application) : AndroidViewModel(app) {

private val roomManager: RoomManager = RoomManagerImpl(app)
private val prefsManager: PrefsManager = PrefsManagerImpl(app)

private val todoItemList: MutableLiveData<List<ToDoItem>> = MutableLiveData()
val todoItemListResult: LiveData<List<ToDoItem>> = todoItemList

fun getAllItems() {
    val result = roomManager.getAllItems()
    todoItemList.postValue(result)
}

fun addItem(item: ToDoItem) {
    val list = todoItemList.value?.let {
        it.toMutableList() + item
    }
    todoItemList.postValue(list)
}

fun updateItem(item: ToDoItem) {
    roomManager.editItem(item)
}

fun deleteItem(item: ToDoItem) {
    val list = todoItemList.value?.let {
        it.toMutableList() - item
    }
    todoItemList.postValue(list)
    roomManager.deleteItem(item)
}

}

And here is activity observer

  viewModel.todoItemListResult.observe(this, Observer {
        data = it
        adapter.updateList(it)
        screenDataValidation(it)
    })

Upvotes: 0

Views: 45

Answers (1)

Андрей Утко
Андрей Утко

Reputation: 329

Why do You use

todoItemList.postValue(list)

The postValue() method is slower because of synchronization costs and not needed in updating from main thread. Just use value.

In the deleteItem method You set data in room and in addItem not?

In other things, Your code seems ok, if You want to avoid unnecessary structures, I would recommend write like that:

if (list.isNullOrEmpty())
    return

todoItemList.value = todoItemList.value + item
roomManager.add(item)

Upvotes: 1

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