Android Kotlin - 将 Gson 转换的 API 数据存储到房间数据库中

Question

我正在使用okhttp 从 API 中获取 Json 数据，将其转换为 Gson 以用于其他目的，同时将 API 数据存储到 Room Database 中。 （可以是API json数据本身的存储，也可以是转换后的Gson版本）但是，我在这方面没有成功，希望你能指出我出错的方向。

我想我缺少一个 typeConverter 来转换从 API 检索并转换为 GSON 的数据，以存储在 Room database 中。但是我不确定我在这方面是否正确，或者我的方法首先是否正确。

或者我有一个Entities data class，但gsonData 被转换为SampleData data class，这可能是一个问题吗？

DataGetter

...
...
...
// this suspend function is run within a coroutine.
private suspend fun APICall(url: String, pageNumber: Int, context: Context){
    val urlRequest = Request.Builder().url(url).build()  // Building of the URL to fetch data
    httpClient.newCall(urlRequest).enqueue(object : Callback {
        // onFailure -> cutting this out to shorten code
        // onResponse is where I am fetching the data and calling put to DB
        override fun onResponse(call: Call, response: Response) {
            val dataString = response.body!!.string()
            val gsonData = gsonResult.fromJson(dataString, SampleData::class.java)
            // Do some other stuffs with gsonData separately. This doesn't return anything to gsonData. 
            putToRoomDb(gsonData, context)  // This will eventually be done via another coroutine.
        }
    }
}

private suspend fun putToRoomDb(sampleData: SampleData, context: Context) {        
    val db = MyOnlyDatabase.getInstance(context)
    db.MyOnlyDao().updateOrInsert(sampleData)
}

实体

@Entity(tableName = "sample_data_code_names")
data class SampleDataEntities(
    @PrimaryKey
    var Code: Int,
    val Name: String,
    val Description: String,
    val Item1: String,
    val Item2: String
) 

道

@Dao
interface SampleDataDao {
    @Insert(onConflict = OnConflictStrategy.REPLACE)
    suspend fun updateOrInsert(sampleDataEntities: SampleDataEntities)
}

数据库

@Database(entities = [SampleDataEntities::class], version = 1, exportSchema = false)
abstract class MyOnlyDatabase: RoomDatabase() {
    abstract fun sampleDataDao(): SampleDataDao 

    companion object {  
        @Volatile
        private var instance: MyOnlyDatabase? = null    
        fun getInstance(context: Context): MyOnlyDatabase{
            return instance ?: synchronized(this) {                   
                instance ?: buildDatabase(context).also { instance = it }
            }
        }

        private fun buildDatabase(context: Context): MyOnlyDatabase{
            return Room.databaseBuilder(context, MyOnlyDatabase::class.java, "MyOnlyDatabase.db")
                .fallbackToDestructiveMigration()                   
                .build()                                                     
        }
    }
}

注意：下面是data class，gsonData 被转换成。

data class SampleData(val value: List<SampleDataInfoItems>)
data class SampleDataInfoItems(
    val Code: String,
    val Name: String,
    val Description: String,
    val Item1: BigDecimal,
    val Item2: BigDecimal
)

Answer 1

您没有根据来自服务器的 JSON 响应来注释您的字段。

data class SampleDataInfoItems(
    @SerializedName("name_this_field_on_json")
    val Code: String,
    @SerializedName("and_so_on_for_all_fields")
    val Name: String,
    val Description: String,
    val Item1: BigDecimal,
    val Item2: BigDecimal
)

另外，我认为您需要 GsonConververFactory 进行改造。