ios - 尝试从 DynamoDB (Swift) 读取时出现 DynamoDBObjectModel 错误

Question

刚刚开始使用 DynamoDB，我正在关注他们的 Swift 示例，但我不断收到相同的错误:'NSInternalInconsistencyException'，原因:'_regionId 不是 TestApp.RegionLocations 的属性。'

带有分区键 regionId 的 DynamoDB 项目如下所示:

{
  "locations": [
    {
      "latitude": 40.1234567,
      "longitude": 70.1234567,
      "name": "Location 1",
      "locationId": "LOCATION1-123"
    },
    {
      "latitude": 41.1234567,
      "longitude": 71.12345678,
      "name": "Location 2",
      "locationId": "Location2-123"
    }
],
  "regionId": "region1"
}

从 AWS 下载的 DynamoDBObjectModel。我完全未受影响:

import Foundation
import UIKit
import AWSDynamoDB

class RegionLocations: AWSDynamoDBObjectModel, AWSDynamoDBModeling {

    var _regionId: String?
    var _locations: [String: String]?

    class func dynamoDBTableName() -> String {

        return -nameOfTable-
    }

    class func hashKeyAttribute() -> String {

        return "_regionId"
    }

      override class func jsonKeyPathsByPropertyKey() -> [AnyHashable: Any] {
          return [
               "_regionId" : "regionId",
               "_locations" : "locations",
      ]
    }
  }

获取在我的 VC 的 ViewDidLoad() 中调用的函数。基本上是从AWS的示例中复制的，更改了变量名称和rangeKey:nil:

func fetchLocations(){

    let dynamoDbObjectMapper = AWSDynamoDBObjectMapper.default()
    let locations: RegionLocations = RegionLocations();
    locations._regionId = "region1"

    dynamoDbObjectMapper.load(
        RegionLocations.self,
        hashKey: locations._regionId!,
        rangeKey: nil,
        completionHandler: {
            (objectModel: AWSDynamoDBObjectModel?, error: Error?) -> Void in
            if let error = error {
                print("Amazon DynamoDB Read Error: \(error)")
                return
            }
            print("An item was read.")
    })
}

已尝试(未成功)在 dynamoDbObjectMapper.load() 内部使用: hashKey: "region1"而不是使用上面代码中的 RegionLocations 对象。还重新启动了 Xcode 并多次清理了项目。我对自己做错了什么感到非常困惑，因为我主要遵循 AWS 的教程。

Answer 1

这可能是由于类成员缺少 @objc 注释而发生的。请更新您的表定义，为所有成员添加 @objc，如下所示:https://docs.aws.amazon.com/aws-mobile/latest/developerguide/add-aws-mobile-nosql-database.html#add-aws-mobile-nosql-database-crud 。原因在这里澄清:https://github.com/aws/aws-sdk-ios/issues/750#issuecomment-337046816

谢谢，罗汉