Possibly fixed-for-good a bug that caused events to be fetched but not stored properly in the database; I believe this was caused by FetcherActivity.kt sequentially executing nukeEvents() and insertEvents(), but doing both asynchronously, and individually, which could mean that insertEvents() finishes before nukeEvents() and therefore nukeEvents() would delete the old events as well as the new ones. This doesn't seem entirely logical to me, as no ConflictStrategy has been configured, and inserting new events before the old ones have been cleared (since they both start their primary keys at 0) would have crashed the app.

app/src/main/java/com/denizk0461/studip/activity/FetcherActivity.kt

@@ -6,10 +6,8 @@ import android.os.Bundle
 import android.webkit.WebResourceRequest
 import android.webkit.WebView
 import android.webkit.WebViewClient
-import android.widget.Toast
 import androidx.lifecycle.ViewModelProvider
 import com.denizk0461.studip.R
-import com.denizk0461.studip.data.StudIPParser
 import com.denizk0461.studip.data.getThemedColor
 import com.denizk0461.studip.databinding.ActivityFetcherBinding
 import com.denizk0461.studip.viewmodel.FetcherViewModel
@@ -72,21 +70,25 @@ class FetcherActivity : Activity() {
             ) { p0 ->
                 try {
                     // Decode HTML and parse it into a list of StudIPEvent.kt
-                    StudIPParser().parse(URLDecoder.decode(p0, "UTF-8")) { events ->
+                    // TODO this exception handling and finish() is broken
-                        // Delete all previously fetched elements
+                    viewModel.parse(URLDecoder.decode(p0, "UTF-8"))
-                        viewModel.nukeEvents()
+//                    StudIPParser(application).parse(URLDecoder.decode(p0, "UTF-8")) { events ->
-
+//
-                        // Insert the list into the database
+//                        // Delete all previously fetched elements
-                        viewModel.insertEvents(events)
+////                        viewModel.nukeEvents()
-
+////                        viewModel.replaceEvents(events)
-                        // Notify the user that the fetch was successful
+//
-                        Toast.makeText(
+//                        // Insert the list into the database
-                            this, R.string.toast_fetch_finished, Toast.LENGTH_SHORT
+////                        viewModel.insertEvents(events)
-                        ).show()
+//
-
+//                        // Notify the user that the fetch was successful
-                        // Close the activity
+//                        Toast.makeText(
-                        finish()
+//                            this, R.string.toast_fetch_finished, Toast.LENGTH_SHORT
-                    }
+//                        ).show()
+//
+//                        // Close the activity
+//                        finish()
+//                    }
                 } catch (e: IOException) {
 
                     // Let the user know that an error occurred

app/src/main/java/com/denizk0461/studip/activity/MainActivity.kt

@@ -1,12 +1,11 @@
 package com.denizk0461.studip.activity
 
 import android.os.Bundle
-import androidx.appcompat.app.AppCompatActivity
 import androidx.core.view.WindowCompat
+import androidx.fragment.app.FragmentActivity
 import androidx.fragment.app.FragmentTransaction
 import androidx.lifecycle.Lifecycle
 import com.denizk0461.studip.R
-import com.denizk0461.studip.data.Dependencies
 import com.denizk0461.studip.databinding.ActivityMainBinding
 import com.denizk0461.studip.db.AppRepository
 import com.denizk0461.studip.fragment.EventFragment
@@ -17,7 +16,7 @@ import com.denizk0461.studip.model.SettingsPreferences
 /**
  * Main activity that handles all common fragments. This is opened on app launch.
  */
-class MainActivity : AppCompatActivity() {
+class MainActivity : FragmentActivity() {
 
     // View binding
     private lateinit var binding: ActivityMainBinding
@@ -36,7 +35,7 @@ class MainActivity : AppCompatActivity() {
          * Instantiate repository object that is accessed by the fragments' view models to retrieve
          * data.
          */
-        Dependencies.repo = AppRepository(application)
+//        Dependencies.repo = AppRepository(application)
 
         // Inflate view binding and bind to this activity
         binding = ActivityMainBinding.inflate(layoutInflater)
@@ -44,7 +43,8 @@ class MainActivity : AppCompatActivity() {
 
         // Open the fragment that the user specified to open on app start
         if (
-            Dependencies.repo.getBooleanPreference(SettingsPreferences.LAUNCH_CANTEEN_ON_START)
+            AppRepository.getRepositoryInstance(application)
+                .getBooleanPreference(SettingsPreferences.LAUNCH_CANTEEN_ON_START)
         ) {
             // Open canteen fragment
             binding.contentMain.navView.selectedItemId = R.id.food

app/src/main/java/com/denizk0461/studip/adapter/StudIPEventItemAdapter.kt

@@ -27,7 +27,7 @@ class StudIPEventItemAdapter(
 ) : RecyclerView.Adapter<StudIPEventItemAdapter.EventViewHolder>() {
 
     /**
-     * List of all events (still not filtered by day at this point)
+     * List of all events.
      */
     private var events: MutableList<StudIPEvent> = mutableListOf()
 

app/src/main/java/com/denizk0461/studip/data/Dependencies.kt

@@ -1,15 +0,0 @@
-package com.denizk0461.studip.data
-
-import com.denizk0461.studip.db.AppRepository
-
-/**
- * Static object that holds a reference to the app's repository to provide abstracted access to the
- * app database.
- */
-object Dependencies {
-    /**
-     * Reference to the app's repository. Since it instantiated once by the main activity, it can be
-     * accessed statically by all other classes. Used for database transactions.
-     */
-    lateinit var repo: AppRepository
-}

app/src/main/java/com/denizk0461/studip/data/StudIPParser.kt

@@ -1,5 +1,7 @@
 package com.denizk0461.studip.data
 
+import android.app.Application
+import com.denizk0461.studip.db.AppRepository
 import com.denizk0461.studip.model.StudIPEvent
 import org.jsoup.Jsoup
 import java.io.IOException
@@ -7,7 +9,9 @@ import java.io.IOException
 /**
  * Parser class used for fetching and collecting scheduled events from a Stud.IP timetable.
  */
-class StudIPParser {
+class StudIPParser(application: Application) {
+
+    private val repo: AppRepository = AppRepository.getRepositoryInstance(application)
 
     /**
      * Parse a given HTML string. HTML must be of a Stud.IP timetable.
@@ -84,7 +88,7 @@ class StudIPParser {
 
                 // Construct the newly scraped Stud.IP event
                 val event = StudIPEvent(
-                    id = id,
+                    eventId = id,
                     title = parsedTitle,
                     lecturer = parsedLecturers,
                     room = entryInfo[1],
@@ -102,7 +106,10 @@ class StudIPParser {
             }
         }
 
+        // Delete all previously saved events
+        repo.nukeEvents()
+
         // After fetching has finished, save the list of new items into persistent storage
-        insert(newEvents)
+        repo.insertEvents(newEvents)
     }
 }

app/src/main/java/com/denizk0461/studip/data/StwParser.kt

@@ -1,5 +1,7 @@
 package com.denizk0461.studip.data
 
+import android.app.Application
+import com.denizk0461.studip.db.AppRepository
 import com.denizk0461.studip.model.*
 import org.jsoup.Jsoup
 import org.jsoup.nodes.Element
@@ -9,7 +11,7 @@ import org.jsoup.select.Elements
  * Parser class used for fetching and collecting canteen offers from the website of the
  * Studierendenwerk Bremen.
  */
-class StwParser {
+class StwParser(application: Application) {
 
     // Unique primary key value for the date elements
     private var dateId = 0
@@ -26,6 +28,11 @@ class StwParser {
     // Determine whether there are offers for a given date
     private var dateHasItems = false
 
+    /**
+     * Static instance of the app's repository.
+     */
+    private val repo: AppRepository = AppRepository.getRepositoryInstance(application)
+
     /**
      * Parses through a list of canteen plans and saves them to persistent storage.
      *
@@ -59,13 +66,13 @@ class StwParser {
         }
 
         // Delete all previous entries and start afresh
-        Dependencies.repo.nukeOffers()
+        repo.nukeOffers()
 
         // Fetch offers from the chosen canteen
         val (dates, canteens, categories, items) = parseFromPage(link)
 
         // Save everything all at once into the database
-        with (Dependencies.repo) {
+        with (repo) {
             insertDates(dates)
             insertCanteens(canteens)
             insertCategories(categories)

app/src/main/java/com/denizk0461/studip/db/AppDAO.kt

@@ -18,7 +18,7 @@ interface AppDAO {
      *
      * @return all Stud.IP events exposed through a LiveData object
      */
-    @get:Query("SELECT * FROM studipevents ORDER BY timeslotId, id")
+    @get:Query("SELECT * FROM studip_events ORDER BY timeslotId, eventId")
     val allEvents: LiveData<List<StudIPEvent>>
 
     /**
@@ -26,7 +26,7 @@ interface AppDAO {
      *
      * @return  Stud.IP events for a certain day exposed through a LiveData object
      */
-    @Query("SELECT * FROM studipevents WHERE day = :day ORDER BY timeslotId, id")
+    @Query("SELECT * FROM studip_events WHERE day = :day ORDER BY timeslotId, eventId")
     fun getEventsForDay(day: Int): LiveData<List<StudIPEvent>>
 
     /**
@@ -62,7 +62,7 @@ interface AppDAO {
     /**
      * Deletes all Stud.IP events from the database.
      */
-    @Query("DELETE FROM studipevents")
+    @Query("DELETE FROM studip_events")
     fun nukeEvents()
 
     /* --- canteen offers --- */

app/src/main/java/com/denizk0461/studip/db/AppDatabase.kt

@@ -17,7 +17,7 @@ import com.denizk0461.studip.model.*
         OfferCategory::class,
         OfferItem::class,
     ],
-    version = 16,
+    version = 18,
 )
 abstract class AppDatabase : RoomDatabase() {
 

app/src/main/java/com/denizk0461/studip/db/AppRepository.kt

@@ -25,6 +25,27 @@ class AppRepository(app: Application) {
     // Blank dietary preference regular expression
     private val blankDietaryPrefs: String = DietaryPreferences.C_FALSE.toString().repeat(10)
 
+    companion object {
+        /**
+         * Reference to the app's repository. It is only instantiated once because it can only be
+         * accessed by [getRepositoryInstance].
+         */
+        private lateinit var repo: AppRepository
+
+        /**
+         * Get a static instance of the repository. If none has been instantiated, one will be created
+         * and saved into [repo].
+         *
+         * @return  static instance of the repository
+         */
+        fun getRepositoryInstance(app: Application): AppRepository {
+            if (!::repo.isInitialized) {
+                repo = AppRepository(app)
+            }
+            return repo
+        }
+    }
+
     /**
      * Retrieves Stud.IP events for a specific day, ordered by their timeslots, then their IDs.
      *

app/src/main/java/com/denizk0461/studip/fragment/EventPageFragment.kt

@@ -66,7 +66,7 @@ class EventPageFragment(
 
         // Set up LiveData observer to refresh the view on update
         viewModel.getEventsForDay(currentDay).observe(viewLifecycleOwner) { events ->
-//            eventAdapter.setNewItems(events)
+
             eventAdapter.setNewData(events)
         }
     }

app/src/main/java/com/denizk0461/studip/model/StudIPEvent.kt

@@ -6,7 +6,7 @@ import androidx.room.PrimaryKey
 /**
  * Entity for storing entries of the user's Stud.IP schedule. Registered in the app database.
  *
- * @param id            primary key that uniquely identifies the entry
+ * @param eventId       primary key that uniquely identifies the entry
  * @param title         title of the event
  * @param lecturer      lecturer(s) organising the event
  * @param room          room the event takes place in
@@ -16,9 +16,9 @@ import androidx.room.PrimaryKey
  * @param timeslotId    minute the event starts at - used for ordering
  * @param colour        user-defined colour the event will be shown in - UNIMPLEMENTED
  */
-@Entity(tableName = "studipevents")
+@Entity(tableName = "studip_events")
 data class StudIPEvent(
-    @PrimaryKey val id: Int,
+    @PrimaryKey val eventId: Int,
     val title: String,
     val lecturer: String,
     val room: String,
@@ -45,7 +45,7 @@ data class StudIPEvent(
 
         other as StudIPEvent
 
-        if (id != other.id) return false
+        if (eventId != other.eventId) return false
         if (title != other.title) return false
         if (lecturer != other.lecturer) return false
         if (room != other.room) return false
@@ -59,7 +59,7 @@ data class StudIPEvent(
     }
 
     override fun hashCode(): Int {
-        var result = id
+        var result = eventId
         result = 31 * result + title.hashCode()
         result = 31 * result + lecturer.hashCode()
         result = 31 * result + room.hashCode()

app/src/main/java/com/denizk0461/studip/sheet/ScheduleUpdateSheet.kt

@@ -133,7 +133,7 @@ class ScheduleUpdateSheet(
             onUpdate(
                 // construct new StudIPEvent from the data the user may have edited
                 StudIPEvent(
-                    id = event.id,
+                    eventId = event.eventId,
                     title = binding.editTextTitle.text.toString(),
                     lecturer = binding.editTextLecturers.text.toString(),
                     room = binding.editTextRoom.text.toString(),

app/src/main/java/com/denizk0461/studip/viewmodel/AppViewModel.kt

@@ -3,7 +3,6 @@ package com.denizk0461.studip.viewmodel
 import android.app.Application
 import androidx.lifecycle.AndroidViewModel
 import androidx.lifecycle.viewModelScope
-import com.denizk0461.studip.data.Dependencies
 import com.denizk0461.studip.db.AppRepository
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
@@ -21,7 +20,7 @@ open class AppViewModel(app: Application) : AndroidViewModel(app) {
     /**
      * Reference to the app's repository for database transactions.
      */
-    protected val repo: AppRepository = Dependencies.repo
+    protected val repo: AppRepository = AppRepository.getRepositoryInstance(app)
 
     /**
      * Execute a function asynchronously on the I/O thread. Be careful not to execute UI commands

app/src/main/java/com/denizk0461/studip/viewmodel/CanteenViewModel.kt

@@ -13,7 +13,7 @@ import com.denizk0461.studip.model.*
 class CanteenViewModel(app: Application) : AppViewModel(app) {
 
     // Instantiate a parser, should the user want to refresh the canteen offers
-    private val parser = StwParser()
+    private val parser = StwParser(app)
 
     /**
      * Retrieves all Stud.IP events.

app/src/main/java/com/denizk0461/studip/viewmodel/FetcherViewModel.kt

@@ -1,7 +1,7 @@
 package com.denizk0461.studip.viewmodel
 
 import android.app.Application
-import com.denizk0461.studip.model.StudIPEvent
+import com.denizk0461.studip.data.StudIPParser
 
 /**
  * View model for [com.denizk0461.studip.activity.FetcherActivity]
@@ -10,15 +10,7 @@ import com.denizk0461.studip.model.StudIPEvent
  */
 class FetcherViewModel(app: Application) : AppViewModel(app) {
 
-    /**
+    private val parser: StudIPParser = StudIPParser(app)
-     * Save a list of Stud.IP events to persistent storage asynchronously.
-     *
-     * @param events    list of events to be saved
-     */
-    fun insertEvents(events: List<StudIPEvent>) { doAsync { repo.insertEvents(events) }}
 
-    /**
+    fun parse(html: String) { doAsync { parser.parse(html, {}) }}
-     * Delete all Stud.IP events from the database asynchronously.
-     */
-    fun nukeEvents() { doAsync { repo.nukeEvents() } }
 }