AWS DynamoDB Batch Get Request - iOS - ios

Question

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.

Answer 1

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};

Answer 2

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
}

Answer 3

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!)
}
}