[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,
    }