Part2.3

Steps

• 2.1 - Create the weather entity
• 2.2 - Write the Weather DAO and set up the Room database
• 2.3 - Update the weather repository and run

2.3 - Update the weather repository and run

We are now ready! We can put all the Room components together to write an room version of our DailyForecastRepository

TODO 🎯 - Create the DailyForecastRepositoryRoomImpl class

Let's create a new version of the DailyForecastRepositoryImpl as a Room version: DailyForecastRepositoryRoomImpl in package domain/repository. Copy the DailyForecastRepositoryImpl class and replace with the code below, which uses WeatherDAO instead of local memory cache.

• Write constructor as follow:

class DailyForecastRepositoryRoomImpl(
    private val weatherDatasource: WeatherDataSource,
    private val weatherDAO: WeatherDAO
) : DailyForecastRepository {

• Remove lastLocationFromCache() function and weatherCache property

Now, we need to rework functions as follow:

• Rewrite getWeatherDetail() function to use directly the DAO:

// Get weather from its id
override fun getWeatherDetail(id: String): Single<DailyForecast> =
    weatherDAO.findWeatherById(id).map { DailyForecast.from(it) }

• Rewrite getWeather() as follow: use 2 functions (getNewWeather() and getWeatherFromLatest()) and requests last weather or a new one:

// Get weather from latest or default one if the location is null
// else get new weather
override fun getWeather(
    location: String?
): Single<List<DailyForecast>> {
    return if (location == null) {
        weatherDAO.findLatestWeather().flatMap { latest: List<WeatherEntity> ->
            if (latest.isEmpty()) getNewWeather(DEFAULT_LOCATION) else getWeatherFromLatest(latest.first())
        }
    } else {
        getNewWeather(location)
    }
}

• Add the following getNewWeather() function to request a new weather for location:

// Get new weather and save it
private fun getNewWeather(location: String): Single<List<DailyForecast>> {
    val now = Date()
    return weatherDatasource.geocode(location)
        .map { it.getLocation() ?: throw IllegalStateException("No Location date") }
        .flatMap { weatherDatasource.weather(it.lat, it.lng, DEFAULT_LANG) }
        .map { it.getDailyForecasts(location) }
        .doOnSuccess { list ->
            weatherDAO.saveAll(list.map { item -> WeatherEntity.from(item, now) })
        }
}

• Add the getWeatherFromLatest() function which requests latest weather data:

// Find latest weather
private fun getWeatherFromLatest(latest: WeatherEntity): Single<List<DailyForecast>> {
    return weatherDAO.findAllBy(latest.location, latest.date)
        .map { list -> list.map { DailyForecast.from(it) } }
}

Now, the DailyForecastRepositoryRoomImpl should compile! ✅

TODO 🎯 - Update Koin configuration:

In room_datasource_module.kt, add and override the DailyForecastRepository definition for the new DailyForecastRepositoryRoomImpl constructor (add an additional get() to fill dependency for constructor, else you'll get a compilation error):

Add the following definition:

// Weather Room Data Repository
single<DailyForecastRepository>(override = true) { DailyForecastRepositoryRoomImpl(get(),get()) }

Note 📖: We keep both implementation of DailyForecastRepository by using moduel configuration change. It also allow us to not break our tests.

TODO 🎯 - Run last tests

• Uncomment WeatherRepositoryTest from Android test
• Comment datasource/WeatherRepositoryTest from unit tests
• Run all tests from Android test WeatherRepositoryTest
• Run the weather app on your device!

Make sure all tests are passing (Unit & Android)!

Congrats, You're done 👍 🍾

The weather app now stores your last location. Kill the app and restart it. You should have your last location instead of the default "Paris" location.