[20 Days of DynamoDB] Day 15 - Using the DynamoDB expression package to build Update expressions

Posted: 31/Jan/2024

The DynamoDB Go SDK expression package supports programmatic creation of Update expressions. Here is an example of how you can build an expression to include execute a SET operation of the UpdateItem API and combine it with a Condition expression (update criteria):

    updateExpressionBuilder := expression.Set(expression.Name("category"), expression.Value("standard"))
    conditionExpressionBuilder := expression.AttributeNotExists(expression.Name("account_locked"))

    expr, _ := expression.NewBuilder().
        WithUpdate(updateExpressionBuilder).
        WithCondition(conditionExpressionBuilder).
        Build()

    resp, err := client.UpdateItem(context.Background(), &dynamodb.UpdateItemInput{
        TableName: aws.String(tableName),
        Key: map[string]types.AttributeValue{
            "email": &types.AttributeValueMemberS{Value: "[e-mail]"},
        },
        UpdateExpression:          expr.Update(),
        ConditionExpression:       expr.Condition(),
        ExpressionAttributeNames:  expr.Names(),
        ExpressionAttributeValues: expr.Values(),
        ReturnValues:              types.ReturnValueAllOld,
    })

Recommended reading - WithUpdate method in the package API docs