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Real-time save design pattern

I use Realm in the application, and I try to abstract as much as possible so that in the future I can change the database providers without any significant changes.

This template worked well, although the following worries me.

  • Creates a new realm object every time overhead (My real understanding is that Realm objects are cached internally)?
  • Are there any problems with the way I use Realm?

  • Are there any better design patterns for my purpose?

    public struct BookDataLayer: BookDataLayerProvider {

func isBookAvailable(bookIdentifier: String) throws -> Bool {
    let database = try getDatabase()
    return !database.objects(Book).filter("identifier = %@", bookIdentifier).isEmpty
}

func createOrUpdateBook(bookIdentifier: String, sortIndex: Int) throws {
    let book = Book()
    Book.bookIdentifier = bookIdentifier
    Book.sortIndex = sortIndex
    try create(book, update: true)
}}

protocol BookDataLayerProvider : DataAccessLayer {
  func isBookAvailable(bookIdentifier: String) throws -> Bool
  func createOrUpdateBook(bookIdentifier: String, sortIndex: Int) throws n} 

  extension DataAccessLayer {

func getDatabase() throws -> Realm {
    do {
        let realm = try Realm()
        // Advance the transaction to the most recent state
        realm.refresh()
        return realm
    } catch {
        throw DataAccessError.DatastoreConnectionError
    }
}

func create(object: Object, update: Bool = false) throws {
    let database = try self.getDatabase()

    do {
        database.beginWrite()
        database.add(object, update: update)
        // Commit the write transaction
        // to make this data available to other threads
        try database.commitWrite()
    } catch {
        throw DataAccessError.InsertError
    }
}}

 // Usage
 let bookDataLayer = BookDataLayer()
 bookDataLayer.isBookAvailable("4557788")

 bookDataLayer.createOrUpdateBook("45578899", 10)
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1 answer

This is a fully rugged construction. For developers, it is quite common to separate data-level APIs from their code if they need to disable it.

In answer to your questions:

  • . Realm , let realm = try! Realm() .
  • , , refresh() Realm , . Realm , refresh(), .
  • "" , , , , , , , !:)
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