删除数据而不是使用迁移

Question

删除数据而不是使用迁移

在我的代码中，我向我的领域类添加了一个属性。有没有办法删除数据并摆脱我的整个数据库而不是使用迁移？

我仍在测试这就是为什么我现在可能不需要迁移。

请帮帮我，我在使用 Migration 时真的很吃力

谢谢

Answer 1

见Realm.Configuration.deleteRealmIfMigrationNeeded。

Answer 2

如果您只是在本地进行测试，您可以删除该应用并重新安装。如果您已经在 App Store 上拥有您的应用并希望为用户准备迁移，您可以查看来自 Realm 的Migrations Sample App。

在你的 AppDelegate 上试试这个：

import UIKit
import RealmSwift

// Old data models
/* V0
class Person: Object {
    dynamic var firstName = ""
    dynamic var lastName = ""
    dynamic var age = 0
}
*/

// V1
class Person: Object {
    dynamic var fullName = ""        // combine firstName and lastName into single field
    dynamic var age = 0
}


class Person: Object {
    dynamic var fullName = ""
    dynamic var age = 0
}

func bundleURL(_ name: String) -> URL? {
    return Bundle.main.url(forResource: name, withExtension: "realm")
}

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey : Any]? = nil) -> Bool {
        window = UIWindow(frame: UIScreen.main.bounds)
        window?.rootViewController = UIViewController()
        window?.makeKeyAndVisible()

        // copy over old data files for migration
        let defaultURL = Realm.Configuration.defaultConfiguration.fileURL!
        let defaultParentURL = defaultURL.deletingLastPathComponent()

        if let v0URL = bundleURL("default-v0") {
            do {
                try FileManager.default.removeItem(at: defaultURL)
                try FileManager.default.copyItem(at: v0URL, to: defaultURL)
            } catch {}
        }

        // define a migration block
        // you can define this inline, but we will reuse this to migrate realm files from multiple versions
        // to the most current version of our data model
        let migrationBlock: MigrationBlock = { migration, oldSchemaVersion in
            if oldSchemaVersion < 1 {
                migration.enumerateObjects(ofType: Person.className()) { oldObject, newObject in
                    if oldSchemaVersion < 1 {
                        // combine name fields into a single field
                        let firstName = oldObject!["firstName"] as! String
                        let lastName = oldObject!["lastName"] as! String
                        newObject?["fullName"] = "\(firstName) \(lastName)"
                    }
                }
            }
            print("Migration complete.")
        }

        Realm.Configuration.defaultConfiguration = Realm.Configuration(schemaVersion: 2, migrationBlock: migrationBlock)

        // print out all migrated objects in the default realm
        // migration is performed implicitly on Realm access
        print("Migrated objects in the default Realm: \(try! Realm().objects(Person.self))")

        return true
    }
}