ios - Realm 不持久写入所做的更改

Question

我有一个函数，我在其中传递一个 payment 和一个 debt 对象(两者都是表示我的 Realm 数据库中数据的结构)。然后我想将 payment 附加到 debt 的 paymentHistory。这是我为此使用的代码:

static func savePayment(payment: Payment, forDebt debt: Debt) throws {
  let realm = try Realm()
  let predicate = NSPredicate(format: "created = %@", debt.created)
  guard let dbDebt = realm.objects(DBDebt.self).filter(predicate).first else { fatalError("no debt found in DB for payment") }
  let dbPayment = DBPayment(payment: payment)
  try realm.write {

    // first try
    // dbDebt.paymentHistory.append(dbPayment)

    // second try
    let newPaymentHistory = dbDebt.paymentHistory
    newPaymentHistory?.append(dbPayment)
    dbDebt.paymentHistory = newPaymentHistory
  }
}

请注意，我包含了我所做的两次尝试的代码，这两次尝试都没有真正持久化数据(我使用 Realm Browser 对此进行了检查)。

另请注意，在调试时，我可以看到 DBPayment 已创建并正确附加到 dbDebt 的列表中。也许我遗漏了一些明显的东西，但我希望它能起作用，因为在 Realm documentation 中，他们声明如下:

为了引用，这里是我的结构和数据库对象的定义:

class DBDebt: Object {

  dynamic var amount: Double = 0.0
  dynamic var owner: DBPerson? = DBPerson()
  var paymentHistory: List<DBPayment>? = List<DBPayment>()
  dynamic var currency: String = Currency.Dollar.rawValue
  dynamic var created: NSDate = NSDate()
  dynamic var deadline: NSDate? = nil

  init(debt: Debt) {
    self.amount = debt.amount
    self.owner = DBPerson(person: debt.owner)
    self.paymentHistory = debt.paymentHistory.reduce(List<DBPayment>()) { (list: List<DBPayment>, payment: Payment) in
      list.append(DBPayment(payment: payment))
      return list
    }
    self.currency = debt.currency.rawValue
    self.created = debt.created
    self.deadline = debt.deadline
    super.init()
  }

  required init(value: AnyObject, schema: RLMSchema) {
    super.init(value: value, schema: schema)
  }

  required init(realm: RLMRealm, schema: RLMObjectSchema) {
    super.init(realm: realm, schema: schema)
  }

  required init() {
    super.init()
  }

}

class DBDebt: Object {

  dynamic var amount: Double = 0.0
  dynamic var owner: DBPerson? = DBPerson()
  var paymentHistory: List<DBPayment>? = List<DBPayment>()
  dynamic var currency: String = Currency.Dollar.rawValue
  dynamic var created: NSDate = NSDate()
  dynamic var deadline: NSDate? = nil

  init(debt: Debt) {
    self.amount = debt.amount
    self.owner = DBPerson(person: debt.owner)
    self.paymentHistory = debt.paymentHistory.reduce(List<DBPayment>()) { (list: List<DBPayment>, payment: Payment) in
      list.append(DBPayment(payment: payment))
      return list
    }
    self.currency = debt.currency.rawValue
    self.created = debt.created
    self.deadline = debt.deadline
    super.init()
  }

  required init(value: AnyObject, schema: RLMSchema) {
    super.init(value: value, schema: schema)
  }

  required init(realm: RLMRealm, schema: RLMObjectSchema) {
    super.init(realm: realm, schema: schema)
  }

  required init() {
    super.init()
  }

}


struct Payment {

  init(amount: Double, paymentDate: NSDate = NSDate()) {
    self.amount = amount
    self.paymentDate = paymentDate
  }

  let amount: Double
  let paymentDate: NSDate

}

class DBPayment: Object {

  dynamic var amount: Double = 0.0
  dynamic var paymentDate: NSDate = NSDate()

  init(payment: Payment) {
    self.amount = payment.amount
    self.paymentDate = payment.paymentDate
    super.init()
  }

  required init(value: AnyObject, schema: RLMSchema) {
    super.init(value: value, schema: schema)
  }

  required init(realm: RLMRealm, schema: RLMObjectSchema) {
    super.init(realm: realm, schema: schema)
  }

  required init() {
    super.init()
  }

}

Answer 1

为了在 Realm 中持久化对象，您必须在 Realm 中调用 add() 函数 (docs)。

以下应该有效:

try realm.write {

  // this persists your dbPayment in your realm!
  realm.add(dbPayment)

  // first try
  // dbDebt.paymentHistory.append(dbPayment)

  // second try
  let newPaymentHistory = dbDebt.paymentHistory
  newPaymentHistory?.append(dbPayment)
  dbDebt.paymentHistory = newPaymentHistory
}