房间不会自动生成主键

Question

我的 API 响应有以下模型：

@Entity(tableName = TABLE_NAME)
class WeatherEntry {

    @PrimaryKey(autoGenerate = true)
    var wID: Long? = null

    @SerializedName("dt")
    @ColumnInfo(name = COLUMN_DATE)
    var date: String = ""

    @SerializedName("city")
    @Embedded(prefix = "location_")
    var location: Location? = null

    @SerializedName("main")
    @Embedded(prefix = "main_")
    var main: Main? = null

    @SerializedName("weather")
    @TypeConverters(Converters::class)
    @Embedded(prefix = "weather_")
    var weather: ArrayList<Weather>? = null

    @SerializedName("wind")
    @Embedded(prefix = "wind_")
    var wind: Wind? = null

}

天气回购 从本地或远程数据源获取数据，我将forceRemote设置为true，否则一开始就没有数据显示。

class WeatherRepository @Inject constructor(@Local var localDataSource: WeatherDataSource, @Remote var remoteDataSource: WeatherDataSource) :
    WeatherDataSource {

   private var caches: MutableList<WeatherEntry> = mutableListOf()
   override fun getWeatherEntries(location: String, forceRemote: Boolean): Flowable<MutableList<WeatherEntry>> {

        if (forceRemote) {
            return refreshData(location)
        } else {
            return if (caches.isNotEmpty()) {
                // if cache is available, return it immediately
                Flowable.just(caches)
            } else {
                // else return data from local storage
                localDataSource.getWeatherEntries(location, false)
                    .take(1)
                    .flatMap(({ Flowable.fromIterable(it) }))
                    .doOnNext { question -> caches.add(question) }
                    .toList()
                    .toFlowable()
                    .filter({ list -> !list.isEmpty() })
                    .switchIfEmpty(refreshData(location)) // If local data is empty, fetch from remote source instead.
            }
        }
    }

    /**
     * Fetches data from remote source.
     * Save it into both local database and cache.
     *
     * @return the Flowable of newly fetched data.
     */
    private fun refreshData(location: String): Flowable<MutableList<WeatherEntry>> {

        return remoteDataSource.getWeatherEntries(location,true).doOnNext({

            // Clear cache
            caches.clear()
            // Clear data in local storage
            localDataSource.deleteAllWeatherEntries()
        }).flatMap(({ Flowable.fromIterable(it) })).doOnNext({ entry ->
            caches.add(entry)
            localDataSource.insertWeatherEntry(entry)
        }).toList().toFlowable()
    }

本地数据源

class WeatherLocalDataSource @Inject constructor(private var weatherDao: WeatherDao): WeatherDataSource {

    override fun insertWeatherEntry(weatherEntry: WeatherEntry) {
        return weatherDao.insert(weatherEntry)
    }

    ...
}

远程数据源 这个绝对有效，因为我从 api.

获取所有信息

class WeatherRemoteDataSource @Inject constructor(var weatherService: WeatherService) :
    WeatherDataSource {

    override fun getWeatherEntries(location: String, forceRemote: Boolean): Flowable<MutableList<WeatherEntry>> {
        return weatherService.getForecast(
            location,
            "json",
            "metric",
            BuildConfig.OPEN_WEATHER_MAP_API_KEY
        ).map(WeatherForecastResponse::weatherEntries)
    }
}

DAO

@Dao
interface WeatherDao {

    ...

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    fun insert(weatherEntry: WeatherEntry)
}

数据库

@Database(
    entities = [(WeatherEntry::class)],
    version = 1
)
abstract class WeatherDatabase : RoomDatabase() {

    abstract fun weatherDao(): WeatherDao
}

所有其他字段都可以正常工作，但 wID 始终为空。我的实现有什么问题？

我已经尝试将其默认值更改为 0 并将类型更改为 Int 但这也不起作用。

Answer 1

尝试制作 id non-nullable:

 @PrimaryKey(autoGenerate = true)
    var wID: Long = 0

编辑： 我在示例代码 here 中找到了这个。您可以使您的@Insert 方法return 成为插入行对象的id，这样您就可以这样做：

在你的道中：

@Insert(onConflict = OnConflictStrategy.REPLACE)
fun insert(weatherEntry: WeatherEntry) : Long

在您的刷新数据方法中：

private fun refreshData(location: String): Flowable<MutableList<WeatherEntry>> {

        return remoteDataSource.getWeatherEntries(location,true).doOnNext({

            // Clear cache
            caches.clear()
            // Clear data in local storage
            localDataSource.deleteAllWeatherEntries()
        }).flatMap(({ Flowable.fromIterable(it) })).doOnNext({ entry ->

            val entryID = localDataSource.insertWeatherEntry(entry)
            entry.wID = entryID
            caches.add(entry)
        }).toList().toFlowable()
    }

Answer 2

阅读https://developer.android.com/reference/androidx/room/PrimaryKey?hl=en#autoGenerate() ，你会得到答案

public boolean autoGenerate ()
Set to true to let SQLite generate the unique id.

When set to true, the SQLite type affinity for the field should be INTEGER.

If the field type is long or int (or its TypeConverter converts it to a long or int), Insert methods treat 0 as not-set while inserting the item.

If the field's type is Integer or Long (or its TypeConverter converts it to an Integer or a Long), Insert methods treat null as not-set while inserting the item.

Answer 3

我的问题的解决方案是将主键类型从“长”更改为“长”(java)

@PrimaryKey(autoGenerate = true) @ColumnInfo(name = "task_id") private Long taskID;

房间不会自动生成主键

Room doesn't autogenerate Primary Key

java

android

kotlin

android-room