Swift 3 AWS DynamoDB json 响应反序列化答案

【问题标题】：Swift 3 AWS DynamoDB json response deserializationSwift 3 AWS DynamoDB json 响应反序列化
【发布时间】：2017-02-09 21:45:27
【问题描述】：

努力了解如何反序列化从 AWS DynamoDB 发送的 json 对象。我能够成功调用 dynamoDB.describeTable(describeTableInput!) 并收到详细的回复...

2017-02-08 20:30:36.054 AWS_Test[84241:3626357] AWSiOSSDK v2.5.0 [Debug] AWSURLResponseSerialization.m line:63 | -[AWSJSONResponseSerializer responseObjectForResponse:originalRequest:currentRequest:data:error:] | Response body:
{"Table":{"AttributeDefinitions":[{"AttributeName":"Author","AttributeType":"S"},{"AttributeName":"ISBN","AttributeType":"S"}],"CreationDateTime":1.486165623131E9,"GlobalSecondaryIndexes":[{"IndexArn":"arn:aws:dynamodb:ap-southeast-2:xxxxxxxxxxxxxxx:table/Books/index/ISBN-index","IndexName":"ISBN-index","IndexSizeBytes":94946,"IndexStatus":"ACTIVE","ItemCount":1780,"KeySchema":[{"AttributeName":"ISBN","KeyType":"HASH"}],"Projection":{"ProjectionType":"ALL"},"ProvisionedThroughput":{"NumberOfDecreasesToday":0,"ReadCapacityUnits":5,"WriteCapacityUnits":5}},{"IndexArn":"arn:aws:dynamodb:ap-southeast-2:xxxxxxxxxxxxxx:table/Books/index/Author-index","IndexName":"Author-index","IndexSizeBytes":94946,"IndexStatus":"ACTIVE","ItemCount":1780,"KeySchema":[{"AttributeName":"Author","KeyType":"HASH"}],"Projection":{"ProjectionType":"ALL"},"ProvisionedThroughput":{"NumberOfDecreasesToday":0,"ReadCapacityUnits":5,"WriteCapacityUnits":5}}],"ItemCount":1780,"KeySchema":[{"AttributeName":"ISBN","KeyType":"HASH"}],"ProvisionedThroughput":{"NumberOfDecreasesToday":0,"ReadCapacityUnits":5,"WriteCapacityUnits":5},"TableArn":"arn:aws:dynamodb:ap-southeast-2:xxxxxxxxxxxxxxxxx:table/Books","TableName":"Books","TableSizeBytes":94946,"TableStatus":"ACTIVE"}}

我的函数调用 Dynamo ...

func describeTable() {

        let dynamoDB = AWSDynamoDB.default()
        let describeTableInput = AWSDynamoDBDescribeTableInput()
        describeTableInput?.tableName = "Books"

        let tableDescription = dynamoDB.describeTable(describeTableInput!) as! AWSTask<AnyObject>

        let jsonResult: NSDictionary = try JSONSerialization.JSONObjectWithData(Data, options: JSONSerialization.ReadingOptions.MutableContainers) as! NSDictionary

        print(jsonResult.object(forKey: "ItemCount")!)
        // let's dump everything to see what was returned
        dump(tableDescription)

    }

但我这几天一直在苦苦挣扎，试图弄清楚如何反序列化响应并将其存储在我自己的字典中。

任何人都可以提供帮助！？谢谢！

【问题讨论】：

标签： json amazon-web-services swift3 amazon-dynamodb

【解决方案1】：

您是否尝试过使用SwiftyJSON library？第三方库将使您免于头疼，尤其是在处理数据时。有了它，你的代码看起来有点像：

let json = JSON(jsonResult)
if let count = json["Table"]["GlobalSecondaryIndexes"]["ItemCount"].int {
  print(count) //your count should be accessible here
}

请记住，JSON 值是嵌套的，因此简单地调用 json["ItemCount"] 不会返回您所期望的。

【讨论】：

【解决方案2】：

在挖掘、尖叫、挖掘和哭泣之后，我在这里找到了提示：https://github.com/awslabs/aws-sdk-ios-samples/blob/master/DynamoDBObjectMapper-Sample/Swift/DynamoDBSampleSwift/DDBDynamoDBManager.swift

重构我的代码让我能够访问响应值..

func describeTable() {
        let dynamoDB = AWSDynamoDB.default()
        let describeTableInput = AWSDynamoDBDescribeTableInput()
        describeTableInput?.tableName = "Books"
        let describeTask = dynamoDB.describeTable(describeTableInput!)

        var localTask:AWSTask<AnyObject>?

        localTask = describeTask.continueOnSuccessWith(block: { task -> AnyObject? in

            let describeTableOutput:AWSDynamoDBDescribeTableOutput = task.result!
            let tableName = describeTableOutput.table!.tableName
            let tableStatus = describeTableOutput.table!.tableStatus
            let itemCount = describeTableOutput.table?.itemCount

            print("--------------------------")
            print(tableName! as String)
            if tableStatus == AWSDynamoDBTableStatus.active {
                print("Active")
            } else {
                print("Inactive")
            }
            print(itemCount as! Int)
            print("--------------------------")

            return localTask
        })
    }

希望这对其他人有帮助！

【讨论】：