ios - Create a realm object during a Realm Migration

Question

Are you able to create a realm Object during a migration? I am wanting to extract part of an existing realm object and create a new object with that data, but the migration always hangs up. Here is my migration code

private class var migrationBlock: MigrationBlock {
    return { migration, oldSchemaVersion in
        if oldSchemaVersion < 1 {
            print("Shema Version 0")
            migration.enumerate(Transaction.className(), { (oldObject, newObject) -> Void in
                let oldDate = oldObject!["date"] as! NSDate
                let newTransactionDate = TransactionDate()
                newTransactionDate.date = oldDate
                try! Realm.getRealm().write { Realm.getRealm().add(newTransactionDate, update: true) }
                newObject!["_date"] = newTransactionDate
            })
        }
    }
}

Answer 1

您可以Migration.create(_:value:)在迁移期间使用创建对象。

https://realm.io/docs/swift/latest/api/Classes/Migration.html#/s:FC10RealmSwift9Migration6createFS0_FTSS5valuePSs9AnyObject__CS_13DynamicObject

它返回MigrationObject的实例。所以你应该使用下标来为其属性赋值。

let oldDate = oldObject!["date"] as! NSDate

let newTransactionDate = migration.create(TransactionDate.className())
newTransactionDate["date"] = oldDate

newObject!["_date"] = newTransactionDate