Importing UniqueObjects and deleting with RxCoreStore

[tosbaha]

Hi,
I am converting my previous CoreStore functions to RxSwift version. My previous code was something like this.

Storage.stack.perform(asynchronous: { transaction in
    let imported = try! transaction.importUniqueObjects(Into(KargoCD.self), sourceArray: kargos)
    transaction.deleteAll(From<KargoCD>(), Where<KargoCD>("NOT (SELF IN %@)", imported))
}, success: { done in
    logger.info("DoneStore")
}, failure: { error in
    logger.error("MyError CoreStore: \(error)")
})

It is basically importing all objects from JSON and deletes non existing objects from CoreStore. Since I don't like using try! I tried to change code to something like below with RxCoreStore

return Storage.stack.rx.perform(asynchronous: { transaction -> [KargoCD] in
    
    do {
        let imported = try transaction.importUniqueObjects(Into(KargoCD.self), sourceArray: kargos)
        transaction.deleteAll(From<KargoCD>(), Where<KargoCD>("NOT (SELF IN %@)", imported))
        return imported
    } catch  {
        return []
    }
})

I know there is rx for DataStack but I can't use transaction.rx so again I had to use transaction directly. Here also I return empty array for catching error which seems hacky. What is the safest way to importUniqueObjects with Rx way. I also come up with below code but I don't know whether it is safe or not because delete transaction and importing is happening in different transactions.

            }.flatMap { kargos -> Observable<[KargoCD]> in
                let imported = Storage.stack.rx.importUniqueObjects(Into(KargoCD.self), sourceArray: kargos)
                return imported
            }.flatMap({ imported -> Observable<[KargoCD]> in
                return Storage.stack.rx.perform(asynchronous: { transaction in
                    transaction.deleteAll(From<KargoCD>(), Where<KargoCD>("NOT (SELF IN %@)", imported))
                    return imported
                })
            })