Storing a List<Object> in Android Room database

Question

I am currently retrieving a JSON Object from the web using RetroFit, the JSON Object I am getting is actually a List of Objects. I would like to store that List into a Room database table.

interface currentNewsService {
    @GET("api/feed")
    fun getFeed(
            @Query("amount") amount: Int,
    ): Deferred<currentNewsResponse>

    companion object{

        operator fun invoke(): currentNewsService {

            val okHttpClient = OkHttpClient.Builder().build()
            return Retrofit.Builder().client(okHttpClient)
                    .baseUrl("https://someUrl")
                    .addCallAdapterFactory(CoroutineCallAdapterFactory())
                    .addConverterFactory(GsonConverterFactory.create())
                    .build().create(currentNewsService::class.java)
        }
    }
}

And I created a data class that gives me access to the response from the RetroFit call. I am getting the response from the web, but I am having issues storing a List of Objects in Room.

data class currentNewsResponse(
        val news: List<News>){
}

Here is an example of the table I am creating in Room:

@Entity(tableName = "news", indices = [Index(value = ["newsId"], unique = true)])
data class Feed(
@PrimaryKey
val id: Int
@SerializedName("current_news_id")
val newsId: Int)

Can anyone point me to any relevant documentation or help me out by giving me an example of how you would come about storing a List of Objects?

Answer 1

Room does not allow you to store List of objects directly.

The answer you are looking for is TypeConverter with which you convert your List of objects to a type that Room allows and convert back to List of objects when querying.

You already use Gson . So, serialize/deserialize your data with Gson inside your TypeConverter .

There are so many tutorials regarding how to do it.

• TypeConverter
• Insert Custom list and get that list in Room using TypeConverter