GRDB for REST models

[ualch9]

This is the previous PR (#684), but targeting feature branch ualch9/persistence and without MetaCodable. GRDB's Codable support was fighting with the code generated by MetaCodable, so I decided to drop it.

• Added new OBAKitCoreTests target for testing against OBAKitCore.framework only.

  • OBAKitTests depends on OBAKit.framework and App.app.
  • OBAKitCoreTests links against only OBAKitCore.framework, so I can focus on Codable/GRDB without fighting the compiler or working without tests. Where appropriate, I moved some tests were moved from OBAKitTests → OBAKitCoreTests.
  • For now, fixture files are included in both OBAKitTests and OBAKitCoreTests target.

• GRDB and REST implementations are contained in their own files.

  • REST models are in OBAKitCore/Models/REST.
  • GRDB implementations are Swift extensions in OBAKitCore/Persistence/Models. In general, GRDB models (such as many-to-many relations) are not exposed outside of OBAKitCore.
  • With few exceptions, REST and GRDB use the same model.

Each model defines their own tables, via protocol DatabaseTableCreator.createTable(in:) that is called by PersistenceManager when initially creating the database.

When storing on-disk, each database is stored per-region: {app_container}/Application Support/regions/{region_id}/onebusaway.sqlite

Undecided:

• What should be persisted (stops only? or everything?). As a first release, the database could operate only in-memory.
• Need to include some sort of expiration date. AFAIK, API responses do not include an expires header.
• How should bookmarks be stored so they can sync via iCloud.
• Objective-C support? Is this important enough that we should write wrappers for the new models?

[aaronbrethorst]

What should be persisted (stops only? or everything?). As a first release, the database could operate only in-memory. Need to include some sort of expiration date. AFAIK, API responses do not include an expires header.

Only in memory sounds like a great first step. That'll help us deal with this problem you outline in point 2 (above).

How should bookmarks be stored so they can sync via iCloud.

Let's defer this just for a little bit. I think getting Sqlite up and running in a way we're comfortable with supporting is enough of a bite at this apple for now.

Objective-C support? Is this important enough that we should write wrappers for the new models?

I don't think so, no. I think we can effectively ignore Obj-C from here on out.

[ualch9]

I think this is ready for review:

• OBAKit does not build. To build & test, run a specific XCTestCase in OBAKitCoreTests (just "building" will complain about no executable).

• Renamed ServiceAlert → Situation (added typealias ServiceAlert = Situation).

• These models have GRDB implementations:

  • Agency
  • Route
  • Situation
  • Stop
  • Trip
  • TripDetails
  • In code, this list is found in PersistenceService.Configuration.tableCreators. Some models may have additional tables, usually to represent relations. These are represented in each model's GRDB implementation as additionalTableCreators (example: SituationDB.swift).

• Tests are kinda messy right now, I'll clean it up later:

  • OBAKitTests/fixtures have their target memberships set to both OBAKitTests and OBAKitCoreTests.
  • Not everything that may be in OBAKitCoreTests has been moved.

• Many of the model structures are now closer to their OBA object schema:

  
  public struct TripDetails: Codable {

• public let timeZone: String

• public let stopTimes: [TripStopTime]

• public let previousTripID: String?

• public let nextTripID: String?

• public let schedule: Schedule

• init(decoder: Decoder) throws {

• // ...

• let schedule = try container.nestedContainer(keyedBy: CodingKeys.self, forKey: .schedule)

• timeZone = try schedule.decode(String.self, forKey: .timeZone)

• stopTimes = try schedule.decode([TripStopTime].self, forKey: .stopTimes)

• previousTripID = try schedule.decodeIfPresent(String.self, forKey: .previousTripID)

• nextTripID = try schedule.decodeIfPresent(String.self, forKey: .nextTripID)

• // ...

• } }

• public struct Schedule: Codable, Hashable {

• public let timeZone: String

• public let stopTimes: [TripStopTime]

• public let previousTripID: String?

• public let nextTripID: String?

• }

  
  Another example is representing the `LocationModel` directly, rather than augmenting it into a `CLLocation`.

Need to do next:

• A service that abstracts fetches from API or database:

  let response = try await restAPIService.getTrip(tripID: tripID, vehicleID: vehicleID, serviceDate: .now)
  try await persistence.processAPIResponse(response) // ← this isn't ergonomic.