Issue when mapping data in .fromNonFlow about store

[yigit]

can you show how you are collecting from the store? Also, if you can produce a simple app that reproduces the issue, that would be very helpful. We have plenty of tests that use fromNonFlow (https://github.com/dropbox/Store/search?q=fromNonFlow&unscoped_q=fromNonFlow) so having a repro sample would help us understand what is going on.

Ok we are producing a simple app to replicate it but for now, we are collecting from it like this...

override fun cacheSensorStream(): Flow<StoreResponse<List<Entity.Sensor>>> =
        createSensorStream(StoreRequest.cached(StoreKey.SensorsKey(), true))

sensorRepository.cacheSensorStream().collect(flowCollector)

We basically add the things we collect to a live data object we are observing, we keep getting no data from the fetcher.

We also realized we didn't add the store key in the body of nonFlow but that still didn't remedy the issue but it looks like this now...

remoteDataSource.getSensors(it).body()?.map(::sensorMapping)!!

[yigit]

I've run the app and if you add a log tot he collector, you'll actually see:

val quoteCollector: FlowCollector<StoreResponse<QuoteData>> = object : FlowCollector<StoreResponse<QuoteData>> {
                override suspend fun emit(value: StoreResponse<QuoteData>) {

                    println("received $value") // <<<<<
                    when(value) {
                        is StoreResponse.Data -> {
                            textView_newQuote.text = value.value.quote
                        }
                        is StoreResponse.Error -> {
                            textView_newQuote.text = value.error.message
                        }
                    }
                }

            }

2020-02-03 23:18:17.236 14525-14525/com.versilistyson.storedemo I/System.out: received Loading(origin=Fetcher)
2020-02-03 23:18:18.299 14525-14525/com.versilistyson.storedemo I/System.out: received Error(error=kotlin.KotlinNullPointerException, origin=Fetcher)

the code gets an NPE because of this line in QuoteRepository:
response.body()!!.map()
which gets forwarded to your collector wrapped in a StoreResponse.Error.

Yeah we are fixing that, sorry should've looked into it more, new app we're pushing soon.

https://github.com/vdtyson/StoreDemo

Same link...not working, api call is successful inside the fetcher.

[yigit]

that one does not work because you've defined your DAO method as

@Update(onConflict = OnConflictStrategy.REPLACE)
suspend fun saveQuote(quoteToSave: QuoteData)

so it does not insert the data into database hence the read method fails to read it back.
changing it to Insert fixes your sample.

Thanks so much. If we lets say wanted to add a different quote to store we'd have to use a new key? Or would writing it using the previous key overwrite it in the dao/cache?

[yigit]

it depends. right now your query returns the first quote in the database (likely to be the very first inserted, but no guarantee by sqlite).

Can you explain what you are trying to do? Do you want to query w/ a specific quote id and get that quote or get all quotes ?

[vdtyson]

We're trying to query for the last quote id returned from the fetcher.

[vdtyson]

Also, every time the generate quote button is clicked, we'd like it to return a new value

[yigit]

so i think what you can do is, write your dao like this:

@Dao
interface QuoteDao {
    @Insert(onConflict = OnConflictStrategy.REPLACE)
    suspend fun saveQuote(quoteToSave: QuoteData)

    @Query("SELECT * FROM quote_table ORDER BY rowId DESC LIMIT 1")
    fun readQuote(): Flow<QuoteData>

    @Delete
    fun deleteQuote(quoteToDelete: QuoteData)
}

Then your read method will always return the last "Edited/inserted" row from the database. Not sure if this is what you want in the long term as it will get invalidated every time a quote enters the database for any reason but this is the best I could think of unless you have to use another field for the quite that is fetched and query by it. That would be something like:

@Dao
interface QuoteDao {
    @Transaction
    suspend fun saveLatestQuote(quoteToSave: QuoteData) {
          unmarkLatestQuote()
          insert(quoteToSave.copy { latestQuote = true })
    }
    @Query("UPDATE QuoteData set latestQuote = 0 WHERE latestQuote = 1")
    suspend fun unmarkLatestQuote()
    @Insert(onConflict = OnConflictStrategy.REPLACE)
    suspend fun saveQuote(quoteToSave: QuoteData)

    @Query("SELECT * FROM quote_table WHERE latestQuote = 1 ORDER BY rowId DESC LIMIT 1")
    fun readQuote(): Flow<QuoteData>

    @Delete
    fun deleteQuote(quoteToDelete: QuoteData)
}