Question

我正在尝试将记录添加到领域数据库表中。

我有一个类Connection，它代表我在数据库中需要的表，并创建了代表列的动态变量：

import Foundation
import RealmSwift
import Realm

open class ConnectionState: Object {

    open dynamic var _id : String = NSUUID().uuidString
    open dynamic var a : String = ""
    open dynamic var b : String = ""
    open dynamic var c : Int = 0

    open override class func primaryKey() -> String? {
        return "_id"
    }

    required public init() {
        super.init()
    }

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

    required public init(value: Any, schema: RLMSchema) {
        fatalError("init(value:schema:) has not been implemented")
    }
}

然后在我的代码中，我尝试编写并提交写事务，如下所示：

let ConnectionState = ConnectionState()
ConnectionState.a = "a"
ConnectionState.b = "b"
ConnectionState.c = 1
try! self.realm.write {
     self.realm.add(ConnectionState)
}

try! self.realm.commitWrite()

运行此代码时，我收到错误：

Can't commit a non-existing write transaction

我错过了什么？我需要在ConnectionState类中使用inits吗？在添加commitWrite之前，我试图用realm浏览器查看数据库。我在xCode中找到了我的设备，并选择下载容器，但它是空的。然后我想我需要添加commitWrite

Answer 1

try! self.realm.write {
     self.realm.add(ConnectionState)
}

这段代码有点等同于（可能还有一些额外的错误处理）：

realm.beginWrite()
...
try! realm.commitWrite()

这意味着您要尝试两次提交。

只需更改您的代码：

try! self.realm.write {
     self.realm.add(ConnectionState)
}

// try! self.realm.commitWrite()

Answer 2

在您的示例中，您调用了commitWrite而未调用beginWrite。您无法提交写入事务，因为您没有启动它。启动写入事务或删除commitWrite行。

启动事务并提交

self.realm.beginWrite()

self.realm.add(ConnectionState)

try! self.realm.commitWrite()

删除commitWrite

try! self.realm.write {
     self.realm.add(ConnectionState)
}

Realm docs有两个向数据库添加数据的例子。

使用realm.write方法

// Use them like regular Swift objects
let myDog = Dog()
myDog.name = "Rex"
myDog.age = 1
print("name of dog: \(myDog.name)")

// Get the default Realm
let realm = try! Realm()

// Query Realm for all dogs less than 2 years old
let puppies = realm.objects(Dog.self).filter("age < 2")
puppies.count // => 0 because no dogs have been added to the Realm yet

// Persist your data easily
try! realm.write {
    realm.add(myDog)
}

使用realm.beginWrite()和realm.commitWrite()启动写入事务并将数据提交到数据库

let realm = try! Realm()

// Break up the writing blocks into smaller portions
// by starting a new transaction
for idx1 in 0..<1000 {
  realm.beginWrite()

  // Add row via dictionary. Property order is ignored.
  for idx2 in 0..<1000 {
    realm.create(Person.self, value: [
      "name": "\(idx1)",
      "birthdate": Date(timeIntervalSince1970: TimeInterval(idx2))
    ])
  }

  // Commit the write transaction
  // to make this data available to other threads
  try! realm.commitWrite()
}

领域提交写入错误 - 无法提交不存在的写入事务

2 个答案: