swift - 领域提交写入错误 - 无法提交不存在的写入事务

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 代表我在数据库中需要的表，并创建了动态变量来代表列：

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，我尝试像这样编写并提交写事务：

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，我收到错误消息：

Can't commit a non-existing write transaction

我错过了什么？我的 ConnectionState 类中是否需要初始化？在添加 commitWrite 之前，我试图用领域浏览器查看数据库。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

score 4 · Accepted Answer

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

这段代码有点等价于（可能有一些额外的错误处理）：

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

这意味着您尝试提交两次写入。

只需像这样更改您的代码：

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

// try! self.realm.commitWrite()

score 4 · Accepted Answer

在您的示例中，您在没有调用的commitWrite情况下调用了beginWrite。你不能提交一个写事务，因为你没有启动一个。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 文档有两个向数据库添加数据的示例。

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()andrealm.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()
}

swift - 领域提交写入错误 - 无法提交不存在的写入事务

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