Use Googles Room Persistency Library

[pfent]

We currently don't have an ORM, but write all SQL queries / mappings by hand.

Google recently released the Android Architecture Components with the Room Persistency Library. We should probably use this, which should significantly reduce the complexity of our various "Managers"

[kordianbruck]

@pfent allowMainThreadQueries() :+1:

[kordianbruck]

Overview: https://speakerdeck.com/hugovisser/room-the-blessed-object-mapper-devfest-bayern

[pfent]

Migrate Managers to use entities and DAOs:

• [x] CafeteriaManager
• [x] CafeteriaMenuManager
• [x] KinoManager
• [x] LocationManager
• [x] OpenHoursManager
• [x] SyncManager
• [x] TumManager
• [x] Calendar Manager
• [x] CardManager
• [x] ChatMessageManager
• [x] ChatRoomsManager
• [x] NewsManager
• [x] NotificationManager
• [x] RecentsManager
• [x] StudyRoomGroupManager
• [x] SurveyManager
• [x] TransportManager
• [x] WifiMeasurementManager

Misc:

• [ ] Migrations / replacement for AbstractManager.resetDb()
• [ ] Use a proper DB abstraction for EnhancedSearchRecentSuggestionsProvider
• [x] Strategy to replace MainThread queries with LiveData / Background Thread

[OliHalu-zz]

@anselm92 @psukys I allready work on ChatMessageManager, ChatRoomsManager

[anselm92]

@pfent @kordianbruck Regarding the strategy to replace main thread queries, i'd suggest using rxandroid (or rxjava in case of persistence api), I've used it many times before and love it :)

See: https://medium.com/google-developers/room-rxjava-acb0cd4f3757

Advantages:

• It's included in the room persistence api
• It's quite easy to use.

I'll implement it for one dao, to show how to use it.

[kordianbruck]

@anselm92 what are the benefits over using livedata?

[anselm92]

Basically:

• Transformations are done on the background thread
• Provides way more functional operations

Are we going to need it? Idk, i thinks it's more a matter of taste

See: https://stackoverflow.com/questions/46312937/when-to-use-rxjava-in-android-and-when-to-use-livedata-from-android-architectura http://akarnokd.blogspot.de/2017/10/android-livedata-api-quick-look.html http://hannesdorfmann.com/android/arch-components-purist

[pfent]

I'd say go for it.

Rxjava would probably also be great for a lot of the Networking stuff, where we currently use AsyncTasks

Building a common rxjava usage pattern for database and network access will award you all the kudos :)

[anselm92]

Alright, I've refactored the first manager (CafeteriaManager) into a viemodel approach with rxjava. (It already works, but it's still more a draft.)

Please have a look and tell me what you think about it:

https://github.com/TCA-Team/TumCampusApp/commit/c24e3996369947d7312ef38c73721ffdd691646b

[psukys]

I like the rxjava approach. I'mma converting NewsManager at the moment.

[psukys]

I haven't added rxjava (even tho PR is still big), will move into DAOizing Calendar manager as NewsManager is ready for review

[kordianbruck]

@TCA-Team/android three left to go :tada:

[psukys]

@OliHalu I take the SurveyManager then