Transaction conditions in DynamoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a condition that the attribute 'status' must equal 'active' in a DynamoDB transaction.

DynamoDB

TransactItems: [{ Update: { Key: { id: '123' }, UpdateExpression: 'SET #s = :new', ConditionExpression: '#s = [1]', ExpressionAttributeNames: { '#s': 'status' }, ExpressionAttributeValues: { ':new': 'inactive', ':active': 'active' } } }]

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

A'inactive'

B'pending'

C'active'

D'deleted'

Attempts:

3 left

💡 Hint

Common Mistakes

Using the new value 'inactive' instead of the current expected value 'active'.

Forgetting to put quotes around the string value.

The condition expression requires the 'status' attribute to be 'active' before updating. So, the correct value is 'active'.

2fill in blank

medium

Complete the code to ensure the transaction only proceeds if the attribute 'count' is less than 10.

DynamoDB

TransactItems: [{ Put: { Item: { id: '456', count: 1 }, ConditionExpression: 'attribute_exists(id) AND [1] < :max', ExpressionAttributeValues: { ':max': 10 } } }]

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

Avalue

Bid

Cstatus

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'id' or other unrelated attributes in the condition.

Omitting the attribute name in the condition expression.

The condition checks that 'count' is less than 10 before putting the item. So 'count' is the correct attribute.

3fill in blank

hard

Fix the error in the condition expression to check that attribute 'version' equals 3 before updating.

DynamoDB

TransactItems: [{ Update: { Key: { id: '789' }, UpdateExpression: 'SET version = version + 1', ConditionExpression: 'version = [1]' } }]

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

A3

B'3'

C:3

D#3

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around the number, which makes it a string.

Using placeholders incorrectly like ':3' or '#3'.

The condition expression compares the attribute 'version' to the number 3, so the value should be the number 3 without quotes or symbols.

4fill in blank

hard

Fill both blanks to create a condition that attribute 'score' is greater than 50 and attribute 'level' is less than 10.

DynamoDB

ConditionExpression: '#sc [1] :minScore AND #lv [2] :maxLevel', ExpressionAttributeNames: { '#sc': 'score', '#lv': 'level' }, ExpressionAttributeValues: { ':minScore': 50, ':maxLevel': 10 }

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

A>

B<

C=

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' instead of comparison operators.

Swapping the operators for the two attributes.

The condition requires 'score' to be greater than 50 and 'level' to be less than 10, so the operators are '>' and '<'.

5fill in blank

hard

Fill all three blanks to build a transaction condition that attribute 'status' equals 'pending', attribute 'attempts' is less than 5, and attribute 'priority' is greater than or equal to 1.

DynamoDB

ConditionExpression: '#st = [1] AND #at [2] :maxAttempts AND #pr [3] :minPriority', ExpressionAttributeNames: { '#st': 'status', '#at': 'attempts', '#pr': 'priority' }, ExpressionAttributeValues: { ':maxAttempts': 5, ':minPriority': 1 }

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

A'pending'

B<

C>=

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around 'pending'.

Using wrong comparison operators like '=' instead of '<' or '>='.

The condition requires 'status' to be 'pending' (string with quotes), 'attempts' less than 5, and 'priority' greater than or equal to 1.