Getting invalid property name when trying to perform Realm migration

Question

I'm having trouble with Realm giving me the error that a property of a given name does not exist for my object. But I know it does exist.

I've tried to follow the docs at https://realm.io/docs/swift/latest/#updating-values. I've searched for everything I can think of to find an applicable solution here and elsewhere, but nothing I've found works.

I previously performed a simple migration to just add properties to a different object within the same Realm. I just left the migration block empty and that worked fine. That migration should have set my schema from 0 to 1. If I run this with my schema set to 1 and to check for versions less than 2, it tells me that migration must be run in order to add these properties. The migration is running. I have a print statement for every time it executes. If I set the schema to 2, still checking for less than 2, I get the error for invalid property name for the old properties unless I uncomment them. Then I still get the error for the new properties.

Here's my Realm object. The commented out lines are the old properties I want to migrate from. The Int values are what I'm migrating to.

@objcMembers class Options: Object {

//    dynamic var morningStartTime: Date?
//    dynamic var afternoonStartTime: Date?
//    dynamic var eveningStartTime: Date?
//    dynamic var nightStartTime: Date?

    dynamic var morningHour: Int = 7
    dynamic var morningMinute: Int = 0

    dynamic var afternoonHour: Int = 12
    dynamic var afternoonMinute: Int = 0

    dynamic var eveningHour: Int = 17
    dynamic var eveningMinute: Int = 0

    dynamic var nightHour: Int = 21
    dynamic var nightMinute: Int = 0

    dynamic var morningNotificationsOn: Bool = true
    dynamic var afternoonNotificationsOn: Bool = true
    dynamic var eveningNotificationsOn: Bool = true
    dynamic var nightNotificationsOn: Bool = true

    dynamic var firstItemAdded: Bool = false

    dynamic var smartSnooze: Bool = false

    dynamic var optionsKey = UUID().uuidString
    override static func primaryKey() -> String? {
        return "optionsKey"
    }

}

My migration block:

    let config = Realm.Configuration(
        // Set the new schema version. This must be greater than the previously used
        // version (if you've never set a schema version before, the version is 0).
        schemaVersion: 2,

        // Set the block which will be called automatically when opening a Realm with
        // a schema version lower than the one set above
        migrationBlock: { migration, oldSchemaVersion in
            // We haven’t migrated anything yet, so oldSchemaVersion == 0

            if (oldSchemaVersion < 2) {

                migration.enumerateObjects(ofType: Options.className(), { (newObject, oldObject) in
                    let morningStartTime = oldObject!["morningStartTime"] as! Date?
                    let afternoonStartTime = oldObject!["afternoonStartTime"] as! Date?
                    let eveningStartTime = oldObject!["eveningStartTime"] as! Date?
                    let nightStartTime = oldObject!["nightStartTime"] as! Date?

                    newObject!["morningHour"] = self.getHour(date: morningStartTime)
                    newObject!["morningMinute"] = self.getMinute(date: morningStartTime)

                    newObject!["afternoonHour"] = self.getHour(date: afternoonStartTime)
                    newObject!["afternoonMinute"] = self.getMinute(date: afternoonStartTime)

                    newObject!["eveningHour"] = self.getHour(date: eveningStartTime)
                    newObject!["eveningMinute"] = self.getMinute(date: eveningStartTime)

                    newObject!["nightHour"] = self.getHour(date: nightStartTime)
                    newObject!["nightMinute"] = self.getMinute(date: nightStartTime)
                })
            }
    })

getHour and getMinute are just functions I wrote to return an Int for the hour or minute from a Date. In case it's relevant, here they are.

func getHour(date: Date?) -> Int {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "HH"
    let hour = dateFormatter.string(from: date!)
    return Int(hour)!
}

func getMinute(date: Date?) -> Int {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "mm"
    let minutes = dateFormatter.string(from: date!)
    return Int(minutes)!
}

Answer 1

I know this is not the way to do it, but I made it work by taking a slightly more manual approach to the migration block. I uncommented the old properties in the Options object and changed my migration function to the following:

func migrateRealm() {

    let configCheck = Realm.Configuration();
    do {
        let fileUrlIs = try schemaVersionAtURL(configCheck.fileURL!)
        print("schema version \(fileUrlIs)")
    } catch  {
        print(error)
    }

    print("performing realm migration")
    let config = Realm.Configuration(
        // Set the new schema version. This must be greater than the previously used
        // version (if you've never set a schema version before, the version is 0).
        schemaVersion: 2,

        // Set the block which will be called automatically when opening a Realm with
        // a schema version lower than the one set above
        migrationBlock: { migration, oldSchemaVersion in
            print("oldSchemaVersion: \(oldSchemaVersion)")
            if (oldSchemaVersion < 2) {
                print("Migration block running")
                DispatchQueue(label: self.realmDispatchQueueLabel).async {
                    autoreleasepool {
                        let realm = try! Realm()
                        let options = realm.object(ofType: Options.self, forPrimaryKey: self.optionsKey)

                        do {
                            try realm.write {
                                if let morningTime = options?.morningStartTime {
                                    options?.morningHour = self.getHour(date: morningTime)
                                    options?.morningMinute = self.getMinute(date: morningTime)
                                }
                                if let afternoonTime = options?.afternoonStartTime {
                                    options?.afternoonHour = self.getHour(date: afternoonTime)
                                    options?.afternoonMinute = self.getMinute(date: afternoonTime)
                                }
                                if let eveningTime = options?.eveningStartTime {
                                    options?.eveningHour = self.getHour(date: eveningTime)
                                    options?.eveningMinute = self.getMinute(date: eveningTime)
                                }
                                if let nightTime = options?.nightStartTime {
                                    options?.nightHour = self.getHour(date: nightTime)
                                    options?.nightMinute = self.getMinute(date: nightTime)
                                }
                            }
                        } catch {
                            print("Error with migration")
                        }

                    }
                }
            }
    })

    // Tell Realm to use this new configuration object for the default Realm
    Realm.Configuration.defaultConfiguration = config

    // Now that we've told Realm how to handle the schema change, opening the file
    // will automatically perform the migration
    _ = try! Realm()
}

This only worked if I queued it on another thread asynchronously. I imagine if this data had been necessary for my initial view controller, then it probably would have created a race condition that caused the app to crash. Luckily this only appears in a secondary view, so it had time to complete before these values are needed. I guess I'll have to remove the unused properties with an updated Realm schema in a future version of my app.