[20 Days of DynamoDB] Day 3 - UpdateItem add-on benefits

Posted: 10/Jan/2024

The DynamoDB UpdateItem operation is quite flexible. In addition to using many types of operations, you can:

• Use multiple update expressions in a single statement
• Get the item attributes as they appear before or after they are successfully updated
• Understand which item attributes failed the condition check (no additional cost)
• Retrieve the consumed Write Capacity Units (WCU)

Here is an example (using AWS Go SDK v2):

    resp, err = client.UpdateItem(context.Background(), &dynamodb.UpdateItemInput{
        TableName: aws.String(tableName),
        Key: map[string]types.AttributeValue{
            "email": &types.AttributeValueMemberS{Value: email},
        },
        UpdateExpression: aws.String("SET last_name = :ln REMOVE category"),
        ExpressionAttributeValues: map[string]types.AttributeValue{
            ":ln": &types.AttributeValueMemberS{
                Value: lastName,
            },
        },
        ReturnValues:                        types.ReturnValueAllOld,
        ReturnValuesOnConditionCheckFailure: types.ReturnValuesOnConditionCheckFailureAllOld,
        ReturnConsumedCapacity:              types.ReturnConsumedCapacityTotal,
    }

Recommended reading:

• UpdateItem API
• Update Expressions