Jetpack paging library return all data

Question

Currently, I'm trying to implement the paging library provided by android jetpack. But I having some troubles when getting the data from DAO. Actually, when I get the data, the PagedList have the size of all the rows in the table!

Here my DAO:

@Dao
interface TableDao {
    @Query("SELECT * FROM table")// I tried also with  ORDER BY field DESC, as I saw in some examples.
    fun getData(): DataSource.Factory<Int, MyEntity>

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    fun insertAll(songs: List<SongEntity>)
}

I trying to satisfy this test:

@Test
fun pageSize() {
    val data = EntityFactory.makeList(50)

    database.getTableDao().apply {
        insertAll(data)

        val pageSize = 5
        RxPagedListBuilder(getData(), pageSize)
                .buildObservable()
                .map { it.size }
                .test()
                .assertValue(pageSize)
    }
}

I don't know if I'm missing some context, but what I wanted to achieve was a progressive loading of the data. Any help/explanation will be very appreciated.

the size is of all the rows in the table, but most entries are null - just print it out with `Log.d` and you will see — pskink, Jul 13 '18 at 10:06
God, you are right, I just get obsessed by seeing the size of the table count. I solved thanks to you. — crgarridos, Jul 13 '18 at 10:15

score 1 · Answer 1 · answered Jul 13 '18 at 10:22

As pointed out by @pskink, there is no problem The PageList ensure the size of the table's count but finally just load items in the measure that they are loaded. In its initialization, it prefetches 3 times the page size. I adapted my test and is pass:

@Test
fun pageSize() {
    val data = EntityFactory.makeList(500)

    database.getTableDao().apply {
        insertAll(data)

        repeat(10) {
            val pageSize: Int = DataFactory.randomInt(5..50)
            RxPagedListBuilder(getData(), pageSize)
                    .buildObservable()
                    .map { it.filterNotNull() }
                    .map { it.size }
                    .test()
                    .assertValue(pageSize * 3)
        }
    }
}

Jetpack paging library return all data

1 Answers1