android - Jetpack Compose 将参数传递给 viewModel

Question

我们如何将参数传递给 viewModel在 Jetpack Compose ?
这是我的可组合

    @Composable
    fun UsersList() {
      val myViewModel: MyViewModel = viewModel("db2name") // pass param like this
    }

这是 viewModel

    class MyViewModel(private val dbname) : ViewModel() {
        private val users: MutableLiveData<List<User>> by lazy {
            MutableLiveData<List<User>>().also {
                loadUsers()
            }
        }
    
        fun getUsers(): LiveData<List<User>> {
            return users
        }
    
        private fun loadUsers() {
            // Do an asynchronous operation to fetch users.
        }
    }

Answer 1

您需要创建一个工厂来将动态参数传递给 ViewModel，如下所示:

class MyViewModelFactory(private val dbname: String) :
    ViewModelProvider.NewInstanceFactory() {
    override fun <T : ViewModel?> create(modelClass: Class<T>): T = MyViewModel(dbname) as T
}

然后在可组合函数中使用你的工厂:

@Composable
fun UsersList() {
    val myViewModel: MyViewModel =
        viewModel(factory = MyViewModelFactory("db2name")) // pass param like this
}

现在您可以访问 ViewModel 中的 dbname 参数:

class MyViewModel(private val dbname) : ViewModel() {
    // ...rest of the viewModel logics here
}