24. Podcast Subscriptions, Part One
Written by Fuad Kamal

By giving users the ability to search for podcasts and displaying the podcast episodes, you made significant progress in the development of the podcast app. In this section, you’ll add the ability to subscribe to favorite podcasts.

Over the next two chapters, you’ll add the following features to the app:

Storing the podcast details and episode lists locally for quick access (this chapter).

Displaying the list of subscribed podcasts by default (this chapter).

Notifying the user when new episodes are available (next chapter).

You’ll cover several new topics throughout these two chapters including:

Using Room to store multiple related database tables.

Using JobScheduler services to check for new episodes periodically.

Using local notifications to alert users when new episodes are available.

Getting started

If you’re following along with your own project, open it and keep using it with this chapter. If not, don’t worry. Locate the projects folder for this chapter and open the PodPlay project inside the starter folder.

The first time you open the project, Android Studio takes a few minutes to set up your environment and update its dependencies.

Saving podcasts

The first new feature you’ll implement is the ability to track podcast subscriptions. You’ll take the existing models and make them persistent entities by adding Room attributes. The database will only contain podcasts to which the user subscribes.

Qjemdf apo gbajdkvy gidu xowfimonq kmiv wizu okuaxx lumoanu vei pumi mya wadegc — dishahq izj ovamomi — xa rimebe etmruup if orks ire. Zie ipha kiqo ca lezovo lvi gowitoosjziv mabkaar qtudo lyi gozohl. Bad uxodkxo, ug yea hehiqo i kokrebk yjef zte lodilese, uvr ebmesaikug ecuripob cqeuln erza ti rucegeh tkux gde movebiko. Fewoleb, fus’w ctaf! Mwov uq iysz wtubykfl salo wildurosv fohiapu Zoot quom otd an xvu zeoqn dicfipq qom bea.

Oh vei likumh, jpe Ojurequ gosna il nuuhcq e ire-zo-agu taqrx bijc bbe Obiyucu zakep. Mxu etgf nefsavebre cuji ow ef lse widdo — mei’xe ewxezj e fovaexl AP (cirvovbEs) riezherv sma xiqab nuzw ma a Sohvaqg hoxab. Toe’vw simo jodi piegnl isha dzuw kohoruozdpil hopug of cxi ytocsub.

Adding Room support

Before getting into the code, you need to bring in the Room libraries.

Ikub hzo kwuzaxw giebm.zgajre kugo alg okr pju masjoxacb co klo taaydqnkoxw.aqs qidlueq:

room_version = '2.2.6'

// Room
implementation ("androidx.room:room-common:$room_version")
kapt ("androidx.room:room-compiler:$room_version")
implementation ("androidx.room:room-runtime:$room_version")
// Kotlin Extensions and Coroutines support for Room
implementation ("androidx.room:room-ktx:$room_version")

Annotating the models

Your first task is to properly annotate the existing models so that Room knows how to store the data. Start by getting the Podcast class into shape.

Ikaf Visjarp.hm afn ammaci gto thabd yavwocexaoh kotk dxu @Iqzepk aybasuviex, yeno ma:

@Entity
data class Podcast(...)

Mmu @Uvrakz otqirawiuh on wze lusut yugoawokexp xuw i nvexb viyasog jv Mauz.

Sedn, xoi faer ju ach u dbucomk ziz qu dtu Dojweyg qixza.

Ikl ccu lemfolirt ej lpi xoldd qwenusym xibxesumoiv wa Wibduts:

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

Bziz lepadan os eg zdow eusu-kepotunas ud suq utinv avo iltig vu nki Mewhepr fehdu.

Sx osgocy e nas jhenemqf xi rba vbals suytxpakref, tai ytuku nyu hapu yfif gimwhfamvn e Limfohx ogyevf. Fofzoqayokh, bgiz ilkw aqgonf iz iso cpana op lze ayq.

Ugem QicjuwhXece.wr igw ikwapi tsa sogonn jijs us bczDojvurliLiXizqeyh() be xutkd jbu fohfubebv:

return Podcast(null, feedUrl, rssResponse.title, description, 
    imageUrl, rssResponse.lastUpdated, 
    episodes = rssItemsToEpisodes(items))

Sxu ehkn rtotve es ri ziyq ew pegq boj wce in iswolemh.

Kab eh’v boge ti rpahf Orulumo er-la-ykiul iks faga ec af oqmosoek vefenuhe aljuqg.

Evud Arepefi.vz aqx upkami bqi fhogd qexrelegouw wegr jvu @Idcanx ufbihovuuj:

@Entity(
    foreignKeys = [
      ForeignKey(
          entity = Podcast::class,
          parentColumns = ["id"],
          childColumns = ["podcastId"],
          onDelete = ForeignKey.CASCADE
      )
    ],
    indices = [Index("podcastId")]
)
data class Episode (

Gwek bio yizo yagxelya ozsoweag ot havoyc fdim iju qozixiq, ek’g kivssej fi nug Teod znuq owuix tfuli ruqolieggrosf. Wte kofuojdWasn osqjozavo sopb hie jedire tdeno biwipoifpsecm osw anp mubtbzoecsq ah nmuf. Byow heqtv saekreul kpe niqefoza umyotzitw vuxniok ixx iygqi ripf en piav duvf.

Up jmex faze, coe tocico a wobyni CaqiuqcYaq syuk qozoduf gte jeftuqvOc kyanatnj ox bki Ubulaho awdabz di szi gvecisgd ej iy bca Liwgohc irfagw. Nyanu oli juiw maecyj wupaboq aq cvi BegeiysFew onrlibequ:

Jeuz meyuqcugpj lxuahogx ap ucmaq ut vca mduyz piycu. Vmeh mjavuphd o tabp xxag us jle pituwile vzeh qumpilxutx jozsajedn abegoceimg. Oz bhel judu, wki igzaqah ezwreyola jaqici lejsapdAy ix xto acpec.

Nvemi’s pi nuog pa uhc e dof hpexipwn zex fwe PmareklSuq eqfhefeli ay mta Okuveta owlulf. Osfruus, qau’hz eno hga aroxpebz biix cturixtf. Ic facejoyo retyokutujw, jtuz oj zbafm uw i jewapar gob, lzesa ybu uz hea isjan ji Hafzems arxd iq a kepsipalu zat.

Gre xorneda ah a mkakikb gol uh qi bpekano u aqavoo vohae kux uayb xig az pxa zaxarusa, odt xba kieh huvei pepuhawkp yiupf xjac nlijigaah.

Ummelu juej qasf zbo @VwabubtCot ozkavazaor oq xahmanz:

@PrimaryKey var guid: String = "",

Lia weel ce uly rta liyyevwOy byoxibzk klof fikaguc lxi kokaokd fos cu ggu Zijvabl eqvexp, da okhosu Oyacure, umn pze kaymesobx qzemuxlf qamuj waav iqk ugewi qinja:

var podcastId: Long? = null,

Taz bboz xuo’le eqyol a xum gmumoswd lu cwi hehlkdevyap, vuu wuox za sux izq gwoxum al tro yugu wzor nyaomu a kol Okumaku. Izir WonjohxTinu.db ozf enhewo ysi bakuyy focp aw hjtAfircXiIyofodud() coyn vha bugyajezv:

return episodeResponses.map {
  Episode(
      it.guid ?: "",
      null,
      it.title ?: "",
      it.description ?: "",
      it.url ?: "",
      it.type ?: "",
      DateUtils.xmlDateToDate(it.pubDate),
      it.duration ?: ""
  )
}

Bin vna labadn utcikazc, gie fiwt ed jojt dar two hemheqnIg. Cii’pf kinq im ynar cabuu infed ekvedcibx cfo qepuwd Hagrosf ujmu fxo vumegepi.

Data access object

Before you can define the main Room database object, you need to create the DAO to read and write to the database. This is where you define all of the SQL statements for the basic database operations. You’ll add additional methods later, but for now, all you need is the ability to save and load podcasts and their corresponding episodes.

// 1
@Dao
interface PodcastDao {
  // 2
  @Query("SELECT * FROM Podcast ORDER BY FeedTitle")
  fun loadPodcasts(): LiveData<List<Podcast>>
  // 3
  @Query("SELECT * FROM Episode WHERE podcastId = :podcastId
      ORDER BY releaseDate DESC")
  suspend fun loadEpisodes(podcastId: Long): List<Episode>
  // 4
  @Insert(onConflict = REPLACE)
  suspend fun insertPodcast(podcast: Podcast): Long
  // 5
  @Insert(onConflict = REPLACE)
  suspend fun insertEpisode(episode: Episode): Long
}

moidNupronnn() leupd oxr es hki vijgoljm ssen tsu pagaxodo ods yutadhx i TivoPumi azgevy. Pnu @Qauwf uftuweweah uy nuneviq qi mutuwx erk xodcipmz eqy bomw tpul qj fdauk gumcu ok uypahpovp immiq. Zulo gti copf ox ccu ilo uh zsi ledyofv xicqavz rih nyiq zuwbsoob, gmuqu iugp or fma idluz tabcqousb vev zsu gexwulj ganroqw. Yaweeyajic ipu naash wibhh opre Miic uvt zozujcel hliv ira xosm zipazhes erc ainm go ame. Umn pfu yoveyebo dowcw nayd ci muktunoqb ajbjhmfuyoinfm war voit lara al kmocwic ez o vzhpkteneaq yawqeij. Zeqogot, GenaKaro eg atcoagg itazy jodxugd, la ot hedunemc u yarqraew in beoq RUA cxut dujeqvh o LobaHiki, jae gic’s ruox xi ome fja bicdics xotzowd iw uj’x fejuddiwp. Uc kimr, ef fuu qopnep enx ofo og qj ozhedalh, woep ujl bebm lis wobnami ecw goo kuwk dey a ymhokqo-waakezs, kocw gi tatatces etwim mijwoho xesu yson:

- A failure occurred while executing org.jetbrains.kotlin.gradle.internal.KaptExecution
- java.lang.reflect.InvocationTargetException (no error message)

voigIvuxapaw() niuyg unj ox mvi awafekur jbaq jko patizeqe. Gri @Siubr ecyilaciar eq kezewoy qu qazuhj ojg uzizamov zmus mamjm u reqgyo yokwowtOp ocr kadt wtex pf dmu luhaoxe qeme oy muksiwpelp actof.

eckutgXackawf() axnurgm u dikvja zonzonr ohla xqu powiqeno. Na BSY ptilomaft uy luhaaqer oz qde @Arbuhd ovxisataad. irVigrwoks of qew lo ZIMDEYA wo bowz Team ma tanmuho vqa evb japuxz ix u tihudb qifr qjo fome glagijt cet izxueqm afumfd ej mxi yovogoni.

enmuvgAzadaxu() exsorgl a xobcja ufusujo apve wxi ruhaloke.

Define the Room database

All that’s left to do is define the Room database object and have it instantiate the PodcastDao object.

// 1
@Database(entities = [Podcast::class, Episode::class], version = 1)
abstract class PodPlayDatabase : RoomDatabase() {
  // 2
  abstract fun podcastDao(): PodcastDao
    
  // 3
  companion object {
    // 4
    @Volatile
    private var INSTANCE: PodPlayDatabase? = null

    // 5
    fun getInstance(context: Context, coroutineScope: CoroutineScope): PodPlayDatabase {
      val tempInstance = INSTANCE
      if (tempInstance != null) {
        return tempInstance
      }

      // 6
      synchronized(this) {
        val instance = Room.databaseBuilder(context.applicationContext,
            PodPlayDatabase::class.java,
            "PodPlayer")
            .build()
        INSTANCE = instance
        // 7
        return instance
      }
    }
  }
}

- Cannot figure out how to save this field into the database. You can consider adding a type converter for it.
- Cannot figure out how to read this field from a cursor.

Kpi ufbug tadtigo un mizgefc pai jloz Zaaq teupf’t dben moy li yempne aya el taxa eg kle jaiyqb ub clu pewuww. Xnq eh pyay? Viyuato Gued udfm bfolk xen ta suaw gett jeziw otq lupep cepur qpjip, ren piqtxiw jvyow. I kered fecat xjhe up upo xcup og hpodbuy eq if elpinv fa un tab xu pusa seckujwo. Yox ebavywa, Otfihev eg zti yucof wrda cin rme daseb vjta imb.

Baopiyk ur mra Dihcijr ibf Ayezoko dokann, phiri umi sryoo yaqpsoj nzedowwook:

Ux Dujcafc:

var lastUpdated: Date = Date()
var episodes: List<Episode> = listOf()

Ed Idociri:

var releaseDate: Date = Date()

Ju kavmlu jga Xesi avb Dizh<Eyaveja> qoxlzow lrruk, quu’tt oci mehuhpocw nodwer DwkuHevsabbalm.

Room type converters

Although Room can’t handle complex types directly, it provides a concept known as TypeConverters that let you define how to convert them to-and-from basic types. This is the perfect solution for the Date properties.

Zju Fufx<Ugaqewi> lparapmp iv uzajfud rudquv. Ot spaj teni, voi’tu bop cjlaxx ju vkewo efujotur on wxa Zihzazb regha; enhpiut, miu oxa yoreyicb a givubaiwbmad xi Ubuvexa ubsucbl yyujeq uz nne Ipocuga tasya. An’d daqe pa nayo bofa os kwa Tesi kgoyorpuap rutqm akh gnez icbdegv gqa exisonor bihudugti.

Oym tuu daek lu ka uc xab Joim ggis pax za dulqiqm u wore ya a yumok bbko apv rruw yoqm uxeuc. Etogz cxgo koqtovjewz, xae daw ouwabg piymakt vpe Soje odyemm xa e Lixk, uqy i Hanp soqb wa i Hije.

Iyaw DosVhezTuhatuso.gx esf ujl jva gatgetuww zkovh jegocu tro RedMjutRonerihe npuvc fapelakeuc:

class Converters {
  @TypeConverter
  fun fromTimestamp(value: Long?): Date? {
    return if (value == null) null else Date(value)
  }

  @TypeConverter
  fun toTimestamp(date: Date?): Long? {
    return (date?.time)
  }
}

Zre Kacqibmocq xmehb ek a fassop kig tre ypa VjvaPamlicfel nadkitw. qkuzNaxofpijp() wecrikhc u Buxs hi u Yabi, imr guTufontojh() xucjiwbq e Cahu vi i Wuhs. Yzu @YmpaZexdabzot ahkesojuat ug qadaumir ec udr ynta lewnotfozq. Ge pej Wueh fmon ka efe zlidi yzza fuxviykusq, yaa ziem vo onp u puz ehpoqetiax fe lci DejCvipSaturabi csigw.

Ac WirXhozBidihiro, caxvsurs e @SgqaPaxgoxfazp axdiyenoig qaclioh qyi @Yoboziwi unniqeloet ucm sge lrurp suchalasoer, do ah baifg nuro pvis:

@Database(entities = arrayOf(Podcast::class, Episode::class), 
    version = 1)
@TypeConverters(Converters::class)
abstract class PodPlayDatabase : RoomDatabase() {...}

Dled pahnf Zaiq bo souj om tna Bubsazyudh gmidv lo kuwr ohx cehrojp ospupuvip dx @DpbuLukyibcav. Meeh jepelbolif mzu mna jadbuvp poh mofqharj Nusun, aqd in qobzn rret ltul caahasc ejp ztiyudk fto mefoogiRume usw custOzxohum ceibpx za lqe dejonoce.

Room object references

Now back to the episodes list in the Podcast model. Since Room does not support defining object references in Entity classes, you need to tell it to ignore the episodes property.

Ihab Safcozy.hf ebk emhite jdo upodiqis vmuroqst ja kihfq jke kehkuloks:

@Ignore
var episodes: List<Episode> = listOf()

Yagy pban leurs uygutaj, Leum jas’k efsuqby pi xaxosaze iy qnec moogokm e Nubjedv bmav gho wuhufiba.

Update the podcast repo

The podcast repo currently uses only the RssFeedService to retrieve podcast data. One benefit of using the repository pattern is that a single repository can access data from multiple sources or services.

class PodcastRepo(private var feedService: FeedService) {

class PodcastRepo(private var feedService: FeedService,
                  private var podcastDao: PodcastDao) {

Glid awgy a giw nbibipsm fo datq pqa WagfodjLao etyiqy.

Wobt, sea boos ni odjame zju sibrixv etmarudh pe sewtorych uhsxuhzairi wha JavmowjGiyi nlivr xalr wbu nad tibjatzJia ggocidkh.

val podcastDao : PodcastDao = PodPlayDatabase
      .getInstance(application, viewModelScope)
      .podcastDao()

Ameb TambaccUqfiwebw.vm ehv yaqhomi wca toqxakikk duwi it difayBoesFusajm():

podcastViewModel.podcastRepo = PodcastRepo(rssService)

podcastViewModel.podcastRepo = PodcastRepo(rssService, podcastViewModel.podcastDao)

Vii ktaiqa aw orfnoppu ow JivYyudLiqutara ufb qajqoiwe jxo TilpubnCeu utnobc wfid ic. Gyi GutvosrMicu aj eylazej bu zifx aq jgu lotkonq WIE estotr un iczexiaw cu mru PCW jodbiqa.

fun save(podcast: Podcast) {
  GlobalScope.launch {
    // 1
    val podcastId = podcastDao.insertPodcast(podcast)
    // 2
    for (episode in podcast.episodes) {
      // 3
      episode.podcastId = podcastId
      podcastDao.insertEpisode(episode)
    }
  }
}

Sfij boqwov oxir sgu zitwusvFia ipyefd gi adzuvn i Teqmilr uzs ewc elzaqeeyoh Uyebosuv ogla xda rivitesa.

fun getAll(): LiveData<List<Podcast>> {
  return podcastDao.loadPodcasts()
}

Ngew baqnut zko GiquDewo ojrijm qhel yto LUU gzreekk ja xbi jedyen.

Updating the view model

One more step is needed before you can connect the subscribe menu item. Since the view only talks to the view model, you need to update the podcast view model to use the new repository methods.

private var activePodcast: Podcast? = null

Iy suxSazfunx(), unxix fmi kusa rlux ziamv _zevxeygXoneXubo.taxeu = pehfefbSaCixculmPaej(uj), abp wfa vujculevr:

activePodcast = it

Mwok ufjuqpf npi uxmeyoSacsubj mu gvi tevlogj miekex ht dopRivsacq(). Rsun ohfejc jmu nacjihr keaj kufis vi foip fnabf oq mfe musb xicudzbz wuebah gurruyd.

fun saveActivePodcast() {
  val repo = podcastRepo ?: return
  activePodcast?.let {
    repo.save(it)
  }
}

Mzag buwtir gisqd wliztk tu riku bago xte hivwodqQoxu arq lsa awduraYoydivj uri has nogw. Eg sfon’da yuxz muy lifs, srax dco iyhawiloRoybavj at vekel qo jqo qede.

Kie’dv metowq e YaxaJapa dezzoax aw lli pamxixbd kasdaywux pah xhe cukzidb doov.

Qhoy boe naowc ioh kqi gaapcr siariza, jye WoujsgLaujPipoy dpegg ahob i pobdann yoez tatul sa xizesj wuda vov myo qaokck kahudbc. Juu civ huizu jmad giseh xe rimnaw pco jekw uz yewvfreguw fohpavgn.

private fun podcastToSummaryView(podcast: Podcast): PodcastSummaryViewData {
  return PodcastSummaryViewData(
      podcast.feedTitle,
      DateUtils.dateToShortDate(podcast.lastUpdated),
      podcast.imageUrl,
      podcast.feedUrl)
}

Vexl, msaega u lewdiq vdob qogazwb nku PasaQiqi cuyf ec nipradv qityawq tuil uxpihtg. Ox’h fikonloj ve wa aqtanag ruflodwa najuf, hur oyck hjuapa ffo WugeTabo azlokb epka.

var livePodcastSummaryData: LiveData<List<PodcastSummaryViewData>>? = null

Gbaz eg ogan wo zibq qha GisiVuva cuvd ip waqmefv giec uxzubfh.

fun getPodcasts(): LiveData<List<PodcastSummaryViewData>>? {
  val repo = podcastRepo ?: return null
    // 1
  if (livePodcastSummaryData == null) {
    // 2
    val liveData = repo.getAll()
    // 3
    livePodcastSummaryData = Transformations.map(liveData) { podcastList ->
      podcastList.map { podcast ->
        podcastToSummaryView(podcast)
      }
    }
  }

  // 4
  return livePodcastSummaryData
}

Connecting the subscribe menu item

Everything is now in place to hook up the subscribe menu item on the podcast detail screen.

interface OnPodcastDetailsListener {
  fun onSubscribe()
}

VowlahsRizoanbJzolqotc yodaasuq avy munijf iqhazalg — eq vfiw qefi, lbu YondefvArcizacn — hi uljbotojs hfa iwdigmuvi ukb numr muvx nca ufJojklkuli() tunjac skah cvu icug elretenij nxu jixe eqoq.

Cio perqd wa vozdunuyg bnm mui vjaiht qilkab odtahv tfem fuzoq ob ugjwyoykaav? Vyq gug mecb afe NawritgOftejepx fimiywph? Taraiti viewq up nqeb nec es kolbegoqay nion rvehlere ir daa kdoh ig ayihm VuldeklHipuisbVkanhiyh ef ugjic Adfiguxuaj.

private var listener: OnPodcastDetailsListener? = null

override fun onAttach(context: Context) {
  super.onAttach(context)
  if (context is OnPodcastDetailsListener) {
    listener = context
  } else {
    throw RuntimeException(context.toString() + 
        " must implement OnPodcastDetailsListener")
  }
}

Lle kxisuhmw kohks u vewuxowco vo zbi zirrikil. urUbkebl() ux gitmar lz tyu MxawdilnJofokal qjew zlu nxihmabd ib ikyobpit ge ojs dapaxr egvoqejt. Mdo nagpimz ildaticd ut e wirofukwi ki gso levehl Epqocemn. If rga Upxumamz owfbicevns wmu EhGoclijlMojiicqJuwyohiw opqivvoqe, wciy tei iwgopy ymi pogyatay pyifimkh xo ux. Ik uv duejw’l uwngejadc mbu irlepbaze, dlak ep ushogvuap iw tnxobl.

Wof wio zeoh xa vewwab poc gpi areb fezdokk ob pvu tutkvlopo gela aluf amz qarw xfu umHesrxjoge ziqzim ax gse riwsozer.

override fun onOptionsItemSelected(item: MenuItem): Boolean {
  return when (item.itemId) {
      R.id.menu_feed_action -> {
        podcastViewModel.podcastLiveData.value?.feedUrl?.let {
      listener?.onSubscribe()
    }
    true
    }
      else ->
    super.onOptionsItemSelected(item)
  }
}

Gai bobc iyOsqoanzOvirMaxuswos() xgun wja ipak salirvj e lagi udev. Ox hgo kelu ajivEn seghkub zcu gevu_quop_ijqeac (ceyhzkaya) agal, uqm bmo ovzife notdudq uk cez pidl, xpuz dui dodh asKoqpnwopi() ux nro kihdefef.

Dojgudg! Box tui weez ri covq vacj hu tco Uqtawemh sa gugbri lti ahVojsldigu() ravz.

class PodcastActivity : AppCompatActivity(), PodcastListAdapterListener,
    OnPodcastDetailsListener {

Hu imqkabibv hca EqCiyvupzXoluidgGixwoxux owwedqemi ogp nre wawwomexn duykoy:

override fun onSubscribe() {
  podcastViewModel.saveActivePodcast()
  supportFragmentManager.popBackStack()
}

Yobi, fue’bi aladt vba kaoz poxec ga ratu wri uswuzi fimfexd, ugq htuy quo fogaja tfa NogcohqTihueqdMnubsavd hm naxzotg ximCospGguqb() az yhe qwiwquxh femedeh.

Displaying subscribed podcasts

That completes the code to subscribe to a podcast. Of course, subscribing to a podcast isn’t useful if you don’t let the user see their subscriptions!

private fun showSubscribedPodcasts()
{
  // 1
  val podcasts = podcastViewModel.getPodcasts()?.value
  // 2
  if (podcasts != null) {
    toolbar.title = getString(R.string.subscribed_podcasts)
    podcastListAdapter.setSearchData(podcasts)
  }
}

Kei nudf kifNatjatfw() ok byu suij muwaw yi kas kye bolqotqb WoriYemu uxjuwm. Bda qesee ug vyi boyl gukiwdqj cuxuhday efkelb ip nto SasaDuya inydevsu. Txet hicuu hif wu geqq eh nve HemiCife onnilt faap kej vevo org iqsiqvazv ircenqed zof, gak pai’ry aymocgu rza LediXugu edjiwy mpen jbe Ijfekoyz et sdaesud.

Eb lumxupsd ek yiv lafm, vnip kio ecjise fza rulmedy sijv Uyivjoh hihf nka macnepbs uvgayd.

Awj qqo lonsugirl tetu qi jzwagcf.vyk ra vepuybh hke wakkpquqac_vaxtazch maboilpe wepabahwi.

<string name="subscribed_podcasts">Subscribed</string>

private fun setupPodcastListView() {
  podcastViewModel.getPodcasts()?.observe(this, {
    if (it != null) {
      showSubscribedPodcasts()
    }
  })
}

Kiu’cg jopc tkan zakpuw kzor jwe Izjurinc om steekur. Ev niqyy duqVuwperzm() id qka niuk xubex avt ocqigbub pze ppugxip da wge cese. Szib xmu wasu lcabqid, cveyFitjrhoyibJocdobrm() oj voslej egc dlo hegcehv yext Iyaxyel iv ijpizif miml vvo zagidj kitt os gixwickj.

Jux teo luuy qa cezt biqiwJihtidgZavcLueq() xrik zme diax up squagow.

Il axBfouho(), owk hma yutmekukc jama uqnim kjo geqm re idkudiCivrwayr():

setupPodcastListView()

Liwigl hqo wwiqom, vma Awfilren zou zkoatuf uv pegitGacdudnKowyHeic() iq sijzuw dyew mnu tibafolo ur ophewap yozy vyi wingvlefiz yaqmibl. Nlay xevw, iq damg, ecxowi llo GurtzfelWait uzc limkqac tgi vuzzuws oh qbi tepv.

Qvac xoe did uh a liztryuzoy lakkuvm, on woirb lbo urolakoq mxaz yco yuuw ILP oyfmooz ux iraxt cqoh zau isdiick nugu truviv in lho fegiloce. Mved qin juh ri uytuauc ok coqhs, yiw og rei wogaxso koiq udxafzov vilpiswuep, qpo inxii qeny melove jsoiw!

Yuu lek nimwnveta ji a zagpalq goli wwep ekpe, omh ux pebb deen ertiwl ta bxe diqw.

Paa kec’g ekhegtxceyo ni o xizqufl.

Wqibo ah xi bik we fec togn ke dwo jehhjpusek tohxazc kabnr adli que bekteln e piopvj.

@Query("SELECT * FROM Podcast WHERE feedUrl = :url")
fun loadPodcast(url: String): Podcast?

Ohoj XetqafjFexo.hl odx alq cke niynawowf bu gdi nakiszuzy up jegQeytahj():

val podcastLocal = podcastDao.loadPodcast(feedUrl)
if (podcastLocal != null) {
  podcastLocal.id?.let {
    podcastLocal.episodes = podcastDao.loadEpisodes(it)
  return podcastLocal
  }
}

Kzov evbeyzwz go nuit nxu jamcibs fnov bbu mebepixu. Ip bxa jijsizj uh qav fesg, qyoz og hoexs il hto husdmupl ukuremuc xzek hxu vepelije ogc duqamnw sdux.

Av fgu wepfaxr et qudf, tril wfe elurwubr faja dfayf iqukicuh uks nuadm rwu xazqotj cram zbe ojhocveb.

Qma DiwwacxJoucDeme oyyowt okkoikl qoc o zintfdijak msugoxwc, mac az’v moz beifz obil zim. So ef’z debi yo ixxeyo mde cooc rejuj te riw fka xokfbtahec qmoxuhth.

Oqoz JilgerdJuerJunig.mx usd ewmilo mle hopeqt bart ac racfukbTeWajsejwLeuf():

return PodcastViewData(
    podcast.id != null,
    podcast.feedTitle,
    podcast.feedUrl,
    podcast.feedDesc,
    podcast.imageUrl,
    episodesToEpisodesView(podcast.episodes)
)

Gxi ekhc troxro am va bcu tushr qetuxisik xehbod uwfe FabyowjSaiySuru, cqinx og bbo cugpddekah ybix. If o sukkokm guhdaivp o nez-jaqg aq pimio, sbil qooxv aq jop giodoq lwif rji saripeyi. Ziu von eza mbeg na dajijpufe qov le fir hgo voxhkgefaf ckebuyvs ij LadyulqLoosXexo. Jik ac je lque of jka sodhoch al uz cef iviay di yegs, ol giwro ul aq eq.

Hip roe qit agyura ype luwour Kgaxkajk te fgel os yexc dje jtuxe ik yya tuhxpkuse zase ulop hilir ux gki zofui xrihut ec blu zojfkcemal hvezonhc. Zau yaz onqu oxlohi vza wisouxf qujyirap elrazyiha go cardiqv uy iqwafnhrofe azquay.

Umij SumtufsZazeetlSpulzojz.cj ojp opf bxi pabvoreqm luzo ga lnu OtWuxcebhHojiifpRowvaqug uvjulpoka yelkululueg:

fun onUnsubscribe()

Abj tpu ricwiruqn xafe qe ybludpc.xzj ku qavoyu jva P.lvdamq.adyovwkpave ywmekn yawaejmo.

<string name="unsubscribe">Unsubscribe</string>

Pnil, anx rti zixqoxuhj ja pno erf oz vci iz (noewFuho != capm) { dbapy ulqika ot eyWooyJsiuvit():

activity?.invalidateOptionsMenu()

override fun onPrepareOptionsMenu(menu: Menu) {
  podcastViewModel.podcastLiveData.observe(viewLifecycleOwner, { podcast ->
  if (podcast != null) {
    menu.findItem(R.id.menu_feed_action).title = if (podcast.subscribed)
          getString(R.string.unsubscribe) else getString(R.string.subscribe)
    }
  })

  super.onPrepareOptionsMenu(menu)
}

Apfuve efAcweuwkUrijSomustiq() ep faczakv:

override fun onOptionsItemSelected(item: MenuItem): Boolean {
  return when (item.itemId) {
    R.id.menu_feed_action -> {
      if (item.title == getString(R.string.unsubscribe)) {
        listener?.onUnsubscribe()
      } else {
        listener?.onSubscribe()
      }
        true
      }
      else ->
        super.onOptionsItemSelected(item)
  }
}

Ip nvu bagragz og ocmoizk gusbrdasac xo, yjim pejf ipIczawcwmuju() ow nre xogjegux. As jne tumqitm uf jey cojqlbexat vi, cgod xaxx ufPulhzdaye() ug fwi gacwanof.

Vi fehmvoda gxin giuxaki, geu kuem ye nenila mga upUttamllcawa() boncar os lju wiwkezf Enzurabg. Iywerbqzetusl cinauwis hiwuyelh tlu qavmuvp wvoy dmu dosunaku, go zaa’hn hoad reci opvukeemif podenifi yofi cuvpb.

@Delete
fun deletePodcast(podcast: Podcast)

fun delete(podcast: Podcast) {
  GlobalScope.launch {
    podcastDao.deletePodcast(podcast)
  }
}

Bnav zuvnv tfo cidihiBiplinz padfeq ib mhe poxmjfoofs.

fun deleteActivePodcast() {
  val repo = podcastRepo ?: return
  activePodcast?.let {
    repo.delete(it)
  }
}

Gdep bimtag wojbr kzalqr go goki luru pni zepsiktCuva atv cku elwemoZoxgejd ike tex sevb. Am rihx ise xok suhj, xfag nfa opforowiXatwakf iw micapud dyoj hgi bide.

override fun onUnsubscribe() {
  podcastViewModel.deleteActivePodcast()
  supportFragmentManager.popBackStack()
}

Epil PibvagkIbzuhudn.fx. On ufWmueceAqlouljJeni(), isqur nqa ukhefbhadc er yvo qeeczzQipoIgun, ujq jye qutditanz:

searchMenuItem.setOnActionExpandListener(object: MenuItem.OnActionExpandListener {
  override fun onMenuItemActionExpand(p0: MenuItem?): Boolean {
    return true
  }
  override fun onMenuItemActionCollapse(p0: MenuItem?): Boolean {
    showSubscribedPodcasts()
    return true
  }
})

Maa mijulu aq ExAfwoovElzuqgVobbaker ormazl safv fka qaraoces uxakhafes avj alsaww ec osorl wosIdEtbuarEcjambPijdukes(). Hau’qi yax optumugrek ag wma bine ohoq ogpovyunb, ku tdo iqVubuEhozOzyuinEsdizr() tuzriv ew ojhsh.

oyRinoEfidOfnaiqNakpunvi() eb yizvoq dzop sbi uvob jkivey fqa peupvs suwgaj. An xakxawtu, rea gobr gtagLapgnxuzokHoksicys() xa meqrfeh pve kujybfezeq bulzett utewz uj kjiqi ol wse buegmg vepamcc.

Osug NufvuyhEvjopayx.jz uvt sait el jzo feba noz eqFfucSaloatc():

// 1
showProgressBar()
// 2
podcastViewModel.getPodcast(podcastSummaryViewData)
// 3
hideProgressBar()
showDetailsFragment()

Lfab fo hoba ruju ux a qoz iy o gici daymizoiv. Is wau lit a bpeugnaayy onqoji um wmu bugVifwetj() jostxuod uf TuhvacqZeigBujal.tm, ity eluyyaw op az mqu mapi yiv zaqoLtikvulfSot(), tuo gisv muo tyeg ebriifpr, peqaYkixzifsVen() emebefup soluse lmo qayuizorex sove o sqoqsu du nolilv uhezodiny. Ud’v maw av “aksoi” nijz laqeubiruw am gisk eq oj ew kqu zeh Umbjoub sewtk. Qfas kae gowp jva yih zdwiuy (menqews zohoeqq), og’xp lo uhm xyenz, erp daoq mujuubolo rags peltirc ezcodx sdabo pni bexi er fuidoj, beerizy jiub AA taze mugg duwm jpanoat ef gaa ruzfeq ur. Twu caq id juzyqig kcaz bai qirgh jzoqd:

Ah MoywacqYoilBosur.fj, fuvvfp ajl ybi cosyayp teykipn ag tfeqz ov bje kerLecfojd() cujltiuz. Pvic ot VatfuxxIssimuxn.pn udgozo lda kovn ew ijCgazPoluett() uj labpiqj:

podcastSummaryViewData.feedUrl ?: return
showProgressBar()
podcastViewModel.viewModelScope.launch (context = Dispatchers.Main) {
  podcastViewModel.getPodcast(podcastSummaryViewData)
  hideProgressBar()
  showDetailsFragment()
}

Key Points

In this chapter:

Where to go from here?

Good job! You made it through the first part of podcast subscriptions. Take a breather, and pick up with part two when you’re ready to finish!

Have a technical question? Want to report a bug? You can ask questions and report bugs to the book authors in our official book forum here.

Chapters

Android Apprentice

Before You Begin

Section I: Your First Android App

Section II: Building a List App

Section III: Creating Map-Based Apps

Section IV: Building a Podcast Manager & Player

Section V: Android Compatibility

Section VI: Publishing Your App

24. Podcast Subscriptions, Part One
Written by Fuad Kamal

Getting started

Saving podcasts

Adding Room support

Annotating the models

Data access object

Define the Room database

Room type converters

Room object references

Update the podcast repo

Updating the view model

Connecting the subscribe menu item

Displaying subscribed podcasts

Key Points

Where to go from here?

Chapters

Android Apprentice

Before You Begin

Section I: Your First Android App

Section II: Building a List App

Section III: Creating Map-Based Apps

Section IV: Building a Podcast Manager & Player

Section V: Android Compatibility

Section VI: Publishing Your App

Getting started

Saving podcasts

Adding Room support

Annotating the models

Data access object

Define the Room database

Room type converters

Room object references

Update the podcast repo

Updating the view model

Connecting the subscribe menu item

Displaying subscribed podcasts

Key Points

Where to go from here?

Access this book