在领域迁移期间创建领域对象 [英] Create a realm object during a Realm Migration

问题描述

您能够在迁移期间创建领域对象吗?我想提取现有领域对象的一部分，并使用该数据创建一个新对象，但是迁移总是挂断.这是我的迁移代码

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
            })
        }
    }
}

推荐答案

您可以在迁移过程中使用Migration.create(_:value:)创建对象.

You can use Migration.create(_:value:) to create object during migration.

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

它返回MigrationObject的实例.因此，您应该使用下标为属性分配一个值.

It returns MigrationObject's instance. So you should use subscripting to assign a value to its property.

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

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

newObject!["_date"] = newTransactionDate

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