Transaction error handling in DynamoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start a transaction in DynamoDB.

DynamoDB

const params = { TransactItems: [[1]] };

Drag options to blanks, or click blank then click option'

A{ Get: { TableName: 'Users', Key: { UserId: '123' } } }

B{ Put: { TableName: 'Users', Item: { UserId: '123' } } }

C{ Delete: { TableName: 'Users', Key: { UserId: '123' } } }

D{ Update: { TableName: 'Users', Key: { UserId: '123' }, UpdateExpression: 'SET Age = :age' } }

Attempts:

3 left

💡 Hint

Common Mistakes

Using Get operation inside TransactItems which is not supported.

Forgetting to wrap the operation inside an object with the operation name as key.

The TransactItems array requires transaction operations like Put. Here, we start with a Put operation.

2fill in blank

medium

Complete the code to catch a transaction cancellation error.

DynamoDB

try {
  await dynamodb.transactWrite(params).promise();
} catch (error) {
  if (error.code === [1]) {
    console.log('Transaction cancelled');
  }
}

Drag options to blanks, or click blank then click option'

A'InternalServerError'

B'ConditionalCheckFailedException'

C'ProvisionedThroughputExceededException'

D'TransactionCanceledException'

Attempts:

3 left

💡 Hint

Common Mistakes

Using ConditionalCheckFailedException which is for condition failures, not transaction cancellation.

Checking for wrong error codes that do not relate to transactions.

The error code TransactionCanceledException indicates a transaction was cancelled in DynamoDB.

3fill in blank

hard

Fix the error in the transaction retry logic by completing the blank.

DynamoDB

let retries = 0;
const maxRetries = 3;
while (retries < maxRetries) {
  try {
    await dynamodb.transactWrite(params).promise();
    break;
  } catch (error) {
    if (error.code === 'TransactionCanceledException' && retries < [1]) {
      retries++;
    } else {
      throw error;
    }
  }
}

Drag options to blanks, or click blank then click option'

AmaxRetries

B5

C0

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using a hardcoded number that does not match maxRetries.

Using zero which prevents any retries.

The retry condition should compare retries with maxRetries to limit retry attempts properly.

4fill in blank

hard

Fill both blanks to check if the transaction error is retryable and log the error message.

DynamoDB

if (error.code === [1]) {
  console.log('Retryable error:', error.[2]);
}

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A'TransactionCanceledException'

Bmessage

Ccode

Dstack

Attempts:

3 left

💡 Hint

Common Mistakes

Logging the error code instead of the message.

Checking for wrong error codes.

Check for TransactionCanceledException to identify retryable errors and log the message property for details.

5fill in blank

hard

Fill all three blanks to build a transaction with condition check, put, and handle cancellation error.

DynamoDB

const params = {
  TransactItems: [
    { ConditionCheck: { TableName: 'Orders', Key: { OrderId: '001' }, ConditionExpression: [1] } },
    { Put: { TableName: 'Orders', Item: { OrderId: '002', Status: 'Pending' } } }
  ]
};

try {
  await dynamodb.transactWrite(params).promise();
} catch (error) {
  if (error.code === [2]) {
    console.log('Transaction failed:', error.[3]);
  } else {
    throw error;
  }
}

Drag options to blanks, or click blank then click option'

A'attribute_not_exists(OrderId)'

B'TransactionCanceledException'

Cmessage

D'attribute_exists(OrderId)'

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'attribute_exists' which would fail if the item does not exist.

Logging the error code instead of the message.

The condition expression ensures the order does not exist before putting a new one. The error code TransactionCanceledException is caught and the error message is logged.