Editor

UserViewModel.kt

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.observability.ui

import android.arch.lifecycle.ViewModel
import com.example.android.observability.persistence.User
import com.example.android.observability.persistence.UserDao
import io.reactivex.Completable
import io.reactivex.Flowable
import io.reactivex.functions.Action
import io.reactivex.internal.operators.completable.CompletableFromAction

/**
 * View Model for the [UserActivity]
 */
class UserViewModel(private val dataSource: UserDao) : ViewModel() {

/**
     * Get the user name of the user.

* @return a [Flowable] that will emit every time the user name has been updated.
     */
    // for every emission of the user, get the user name
    fun userName(): Flowable<String> {
        return dataSource.getUserById(USER_ID)
                .map { user -> user.userName }
    }

/**
     * Update the user name.
     * @param userName the new user name
     * *
     * @return a [Completable] that completes when the user name is updated
     */
    fun updateUserName(userName: String): Completable {
        return CompletableFromAction(Action {
            val user = User(USER_ID, userName)
            dataSource.insertUser(user)
        })
    }

companion object {
        // using a hardcoded value for simplicity
        const val USER_ID = "1"
    }
}