CODEWITHSUNDEEP
iosobjective-camazon-web-servicesamazon-dynamodb
memyselfandmyiphone
memyselfandmyiphone

Reputation: 1110

AWS DynamoDB Batch Get Request - iOS

I can perform a simple Get request on a singular table within AWS dynamoDB however when I expand it to a Batch Request across multiple tables I continue to get a error 

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

I understand this as the values not being passed correctly but I can't see what the issue is with my code

//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;
}];

Searched the internet high and low but cannot see a working example of a batch request using iOS Objective C (or swift for that matter).

I have tested both variables on a single Get request and they both work.

Upvotes: 4

Views: 1660

Answers (3)

inga
inga

Reputation: 1

Swift 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.
  • This code assumes that you've configured your AWSServiceConfiguration in the AppDelegate application didFinishLaunchingWithOptions method.

    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!)
        }
    }

    Upvotes: 0

    • Niklas
    Niklas

    Reputation: 1331

    Since the batch get doesn't map to a class I solved it by doing this instead.

    I solved it by doing this,

        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
    }

    Upvotes: 1

    Yosuke
    Yosuke

    Reputation: 3759

    You forgot to wrap around AWSDynamoDBAttributeValue in AWSDynamoDBKeysAndAttributes. Here is a simple example from AWSDynamoDBTests.m:

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

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

    Upvotes: 3

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