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RoomDBViewModel.kt
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RoomDBViewModel.kt
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package com.mindorks.kotlinFlow.learn.room
import androidx.lifecycle.LiveData
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import com.mindorks.kotlinFlow.data.api.ApiHelper
import com.mindorks.kotlinFlow.data.local.DatabaseHelper
import com.mindorks.kotlinFlow.data.local.entity.User
import com.mindorks.kotlinFlow.utils.Resource
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.flow.*
import kotlinx.coroutines.launch
class RoomDBViewModel(private val apiHelper: ApiHelper, private val dbHelper: DatabaseHelper) :
ViewModel() {
private val users = MutableLiveData<Resource<List<User>>>()
init {
fetchUsers()
}
private fun fetchUsers() {
viewModelScope.launch {
users.postValue(Resource.loading(null))
dbHelper.getUsers()
.flatMapConcat { usersFromDb ->
if (usersFromDb.isEmpty()) {
return@flatMapConcat apiHelper.getUsers()
.map { apiUserList ->
val userList = mutableListOf<User>()
for (apiUser in apiUserList) {
val user = User(
apiUser.id,
apiUser.name,
apiUser.email,
apiUser.avatar
)
userList.add(user)
}
userList
}
.flatMapConcat { usersToInsertInDB ->
dbHelper.insertAll(usersToInsertInDB)
.flatMapConcat {
flow {
emit(usersToInsertInDB)
}
}
}
} else {
return@flatMapConcat flow {
emit(usersFromDb)
}
}
}
.flowOn(Dispatchers.Default)
.catch { e ->
users.postValue(Resource.error(e.toString(), null))
}
.collect {
users.postValue(Resource.success(it))
}
}
}
fun getUsers(): LiveData<Resource<List<User>>> {
return users
}
}