AWS DynamoDB批量获取请求 - iOS

Posted 2021-04-07

我可以在AWS dynamoDB中的单个表上执行简单的Get请求，但是当我将其扩展到跨多个表的批处理请求时，我仍然会收到错误

validation error detected: Value null at 'requestItems.rip.member.keys' failed to satisfy constraint

我理解这是因为没有正确传递值，但我无法看到我的代码存在什么问题

//Create Request Values
AWSDynamoDBGetItemInput *getItem = [AWSDynamoDBGetItemInput new];
AWSDynamoDBAttributeValue *hashValue = [AWSDynamoDBAttributeValue new];
hashValue.S = @"User Test";
getItem.key = @{@"ripId": hashValue};

//Create Request Values 2 
AWSDynamoDBGetItemInput *getItem2 = [AWSDynamoDBGetItemInput new];
AWSDynamoDBAttributeValue *hashValue2 = [AWSDynamoDBAttributeValue new];
hashValue2.S = @"User Test";
getItem2.key = @{@"chat": hashValue2};

//Combine to Batch Request
AWSDynamoDBBatchGetItemInput * batchFetch = [AWSDynamoDBBatchGetItemInput new];
batchFetch.requestItems = @{ @"rip": getItem,
                             @"chat": getItem,};

[[dynamoDB batchGetItem:batchFetch] continueWithBlock:^id(BFTask *task) {
    if (!task.error) {

        NSLog(@"BOY SUCCES");

    } else {
        NSLog(@" NO BOY SUCCESS %@",task.error);
    }
    return nil;
}];

搜索了互联网的高低，但无法看到使用ios Objective C（或swift）的批量请求的工作示例。

我已在单个Get请求中测试了这两个变量，但它们都有效。

答案

你忘了在AWSDynamoDBAttributeValue环绕AWSDynamoDBKeysAndAttributes。以下是AWSDynamoDBTests.m的一个简单示例：

AWSDynamoDBKeysAndAttributes *keysAndAttributes = [AWSDynamoDBKeysAndAttributes new];
keysAndAttributes.keys = @[@{@"hashKey" : attributeValue1},
                           @{@"hashKey" : attributeValue2}];
keysAndAttributes.consistentRead = @YES;

AWSDynamoDBBatchGetItemInput *batchGetItemInput = [AWSDynamoDBBatchGetItemInput new];
batchGetItemInput.requestItems = @{table1Name: keysAndAttributes};

另一答案

由于批处理get没有映射到类，我通过这样做来解决它。

我解决了这个问题，

    let dynamoDBObjectMapper = AWSDynamoDBObjectMapper.defaultDynamoDBObjectMapper()
    let task1 = dynamoDBObjectMapper.load(User.self, hashKey: "rtP1oQ5DJG", rangeKey: nil)
    let task2 = dynamoDBObjectMapper.load(User.self, hashKey: "dbqb1zyUq1", rangeKey: nil)

    AWSTask.init(forCompletionOfAllTasksWithResults: [task1, task2]).continueWithBlock { (task) -> AnyObject? in
        if let users = task.result as? [User] {
            print(users.count)
            print(users[0].firstName)
            print(users[1].firstName)
        }
        else if let error = task.error {
            print(error.localizedDescription)
        }
        return nil
    }

另一答案

斯威夫特3

I was able to get the BatchGet request work with the following code. Hope this helps someone else who's struggling with the lack of Swift Docs.

此代码假定您已在AppDelegate应用程序didFinishLaunchingWithOptions方法中配置了AWSServiceConfiguration。 let DynamoDB = AWSDynamoDB.default() // define your primary hash keys let hashAttribute1 = AWSDynamoDBAttributeValue() hashAttribute1?.s = "NDlFRTdDODEtQzNCOC00QUI5LUFFMzUtRkIyNTJFNERFOTBF" let hashAttribute2 = AWSDynamoDBAttributeValue() hashAttribute2?.s = "MjVCNzU3MUQtMEM0NC00NEJELTk5M0YtRTM0QjVDQ0Q1NjlF" let keys: Array = [["userID": hashAttribute1], ["userID": hashAttribute2]] let keysAndAttributesMap = AWSDynamoDBKeysAndAttributes() keysAndAttributesMap?.keys = keys as? [[String : AWSDynamoDBAttributeValue]] keysAndAttributesMap?.consistentRead = true let tableMap = ["Your-Table-Name" : keysAndAttributesMap] let request = AWSDynamoDBBatchGetItemInput() request?.requestItems = tableMap as? [String : AWSDynamoDBKeysAndAttributes] request?.returnConsumedCapacity = AWSDynamoDBReturnConsumedCapacity.total DynamoDB.batchGetItem(request!) { (output, error) in if output != nil { print("Batch Query output?.responses?.count:", output!.responses!) } if error != nil { print("Batch Query error:", error!) } }