Obtain entity using coroutines api

问题

What is the best way to use coroutines with LiveData for selecting some data from database using Room.

This is My Dao class with suspended selection

@Dao
interface UserDao {

    @Query("SELECT * from user_table WHERE id =:id")
    suspend fun getUser(id: Long): User
}

Inside of View Model class I load user with viewModelScope.

Does it correct way to obtain user entity ?

fun load(userId: Long, block: (User?) -> Unit) = viewModelScope.launch {
    block(database.load(userId))
}

According developer android mentioned

val user: LiveData<User> = liveData {
    val data = database.loadUser() // loadUser is a suspend function.
    emit(data)
}

This chunk of code does not work

回答1:

Your Room must return LiveData.

Use instead:

@Dao
interface UserDao {

    @Query("SELECT * from user_table WHERE id =:id")
    fun getUser(id: Long): LiveData<User>
}

来源：https://stackoverflow.com/questions/59859988/obtain-entity-using-coroutines-api