Return values on write in DynamoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the return values when putting an item in DynamoDB.

DynamoDB

response = table.put_item(Item=item, ReturnValues='[1]')

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

AALL_OLD

BUPDATED_NEW

CNONE

DALL_NEW

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ALL_NEW' when you want no return values causes unnecessary data to be returned.

Leaving ReturnValues empty defaults to 'NONE', but explicitly setting it is clearer.

The ReturnValues parameter controls what is returned after a write operation. 'NONE' means no attributes are returned.

2fill in blank

medium

Complete the code to return the updated attributes after updating an item.

DynamoDB

response = table.update_item(Key=key, UpdateExpression=expr, ReturnValues='[1]')

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

ANONE

BALL_NEW

CALL_OLD

DUPDATED_NEW

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'NONE' returns no attributes, so you won't see the update results.

Confusing 'ALL_OLD' with 'UPDATED_NEW' returns old attributes before update.

'UPDATED_NEW' returns only the attributes that were updated by the operation.

3fill in blank

hard

Fix the error in the code to return the entire item after a put operation.

DynamoDB

response = table.put_item(Item=item, ReturnValues='[1]')

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

ANONE

BALL_OLD

CALL_NEW

DUPDATED_NEW

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ALL_NEW' with put_item causes a syntax error.

Expecting put_item to return the new item with 'ALL_NEW' is incorrect.

For put_item, the only valid ReturnValues are 'NONE' or 'ALL_OLD'. 'ALL_NEW' is invalid and causes an error.

4fill in blank

hard

Fill both blanks to return the old item attributes after deleting an item.

DynamoDB

response = table.delete_item(Key=key, ReturnValues='[1]')
old_item = response.get('[2]')

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

AALL_OLD

BAttributes

CNONE

DItem

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'NONE' returns no attributes, so old_item will be None.

Trying to access response['Item'] instead of response['Attributes'].

Setting ReturnValues to 'ALL_OLD' returns the deleted item's attributes under the 'Attributes' key in the response.

5fill in blank

hard

Fill all three blanks to update an item and get the entire new item back.

DynamoDB

response = table.update_item(Key=key, UpdateExpression=expr, ReturnValues='[1]')
new_item = response.get('[2]')
print(new_item.get('[3]'))

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

AALL_NEW

BAttributes

CName

DNONE

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'NONE' returns no attributes, so new_item will be None.

Trying to access a key not present in the updated attributes.

ReturnValues='ALL_NEW' returns the entire updated item under 'Attributes'. Accessing 'Name' gets the updated attribute value.

Practice

1. What does the ReturnValues parameter do in a DynamoDB write operation?

easy

A. It specifies what data should be returned after the write operation.

B. It controls the write capacity units consumed by the operation.

C. It sets the timeout duration for the write request.

D. It defines the table where data will be written.

Solution

1. Step 1: Understand the role of ReturnValues

   The ReturnValues parameter tells DynamoDB what data to send back after a write, such as old or new item attributes.

2. Step 2: Differentiate from other parameters

   ReturnValues does not affect capacity, timeout, or table selection; it only controls returned data.

3. Final Answer:

   It specifies what data should be returned after the write operation. -> Option A

4. Quick Check:

   ReturnValues controls returned data [OK]

Hint: ReturnValues returns data after write, not capacity or timeout [OK]

Common Mistakes:

• Confusing ReturnValues with capacity settings
• Thinking it sets request timeout
• Assuming it selects the table

2. Which of the following is the correct syntax to request the old item attributes after an update in DynamoDB using ReturnValues?

easy

A. "UPDATED_NEW"

B. "NONE"

C. "ALL_NEW"

D. "ALL_OLD"

Solution

1. Step 1: Recall ReturnValues options

   ReturnValues can be NONE, ALL_OLD, UPDATED_OLD, ALL_NEW, UPDATED_NEW.

2. Step 2: Identify option for old attributes after update

   "ALL_OLD" returns the entire item as it was before the update.

3. Final Answer:

   "ALL_OLD" -> Option D

4. Quick Check:

   Old attributes = ALL_OLD [OK]

Hint: Old data after update is ALL_OLD [OK]

Common Mistakes:

• Using ALL_NEW to get old data
• Confusing UPDATED_NEW with old data
• Setting NONE expecting data back

3. Given this DynamoDB update command snippet:

{
  TableName: "Users",
  Key: { "UserId": "123" },
  UpdateExpression: "SET Age = :newAge",
  ExpressionAttributeValues: { ":newAge": 30 },
  ReturnValues: "UPDATED_NEW"
}

What will the response contain?

medium

A. The entire item before the update.

B. Only the new Age attribute after the update.

C. No attributes, just success confirmation.

D. The entire item after the update.

Solution

1. Step 1: Understand ReturnValues "UPDATED_NEW" meaning

   This option returns only the attributes that were updated with their new values.

2. Step 2: Apply to given update

   The update changes Age to 30, so response includes only Age with value 30.

3. Final Answer:

   Only the new Age attribute after the update. -> Option B

4. Quick Check:

   UPDATED_NEW returns updated attributes [OK]

Hint: UPDATED_NEW returns only changed attributes with new values [OK]

Common Mistakes:

• Expecting full item back with UPDATED_NEW
• Confusing UPDATED_NEW with ALL_NEW
• Assuming no data returned with UPDATED_NEW

4. You wrote this DynamoDB PutItem request:

{
  TableName: "Products",
  Item: { "Id": "001", "Name": "Pen" },
  ReturnValues: "UPDATED_OLD"
}

But you get an error. What is wrong?

medium

A. ReturnValues must be set to "ALL_NEW" for PutItem.

B. The Item attribute is missing required keys.

C. "UPDATED_OLD" is invalid for PutItem operations.

D. TableName is incorrect.

Solution

1. Step 1: Check ReturnValues compatibility with PutItem

   PutItem supports only NONE or ALL_OLD for ReturnValues; UPDATED_OLD is invalid.

2. Step 2: Confirm other parameters

   Item and TableName are correct; error is due to invalid ReturnValues.

3. Final Answer:

   "UPDATED_OLD" is invalid for PutItem operations. -> Option C

4. Quick Check:

   PutItem supports NONE or ALL_OLD only [OK]

Hint: PutItem allows NONE or ALL_OLD only for ReturnValues [OK]

Common Mistakes:

• Using UPDATED_OLD with PutItem
• Assuming ALL_NEW required for PutItem
• Mistaking missing keys as cause

5. You want to update a user's email in DynamoDB and get back the entire updated item in one request. Which ReturnValues option should you use in your UpdateItem call?

hard

A. "ALL_NEW"

B. "UPDATED_OLD"

C. "NONE"

D. "ALL_OLD"

Solution

1. Step 1: Understand the goal

   You want the full updated item returned after the update.

2. Step 2: Match ReturnValues option

   "ALL_NEW" returns the entire item as it looks after the update.

3. Final Answer:

   "ALL_NEW" -> Option A

4. Quick Check:

   Full updated item = ALL_NEW [OK]

Hint: Use ALL_NEW to get full updated item after update [OK]

Common Mistakes:

• Choosing UPDATED_OLD which returns old updated attributes
• Using NONE expecting data back
• Selecting ALL_OLD which returns old full item