avro-codegen-cli

How to guide for Avro DTO's....

In this guide I will try to explain how to generate/update avro schemas and some tricks. Do not forget that we will run everything in the project root.

How to add new Schema DTO?

Connect to AWS Dev vpn and run this command.

go run models/avro-dto/main.go -schema=<Key of your schema> -version=<version as int> -package=<package name !(not mandatory)>

How to create new one to replace? (this is not version update)

Connect to AWS Dev vpn and run this command.

go run models/avro-dto/main.go -schema=<Key of new schema> -version=<version as int> -package=<package name !(not mandatory)>

Then find the references of old one by looking for this line.

"github.com/yusufpapurcu/papel/models/avro-dto/<key of old schema>"

After being sure everything updated and tests passing, you can remove the old one's directory.

How to do version update?

Learn the version you want to generate, and be sure it's compatible with the one in schema-versions.env

Also learn the name of the exiting package. You can check one of the generated files.

Connect to AWS Dev vpn and run this command.

go run models/avro-dto/main.go -schema=<Key of new schema> -version=<version as int> -package=<package name>

By keeping package name consistent, you don't need to do renames. Just be sure you reflect changes you do in the code!

How to map nullable field into generated DTO?

So let's look into an example case:

type CustomerContext string

const (
	CustomerContextEcom      CustomerContext = "ECOM"
	CustomerContextTerminal  CustomerContext = "TERMINAL"
	CustomerContextPhone     CustomerContext = "PHONE"
	CustomerContextPayByLink CustomerContext = "PAY_BY_LINK"
)

type CanonicalTransaction struct {
    CustomerContext   *CustomerContext             `json:"customer_context"`
}

So in our domain model we have CustomerContext which is a nullable enum. So in order to map this data into schema dto, you will need to use a block like this:

if data.CustomerContext != nil {
    res.Customer_context = avro_dto.NewCustomer_contextUnion()
    res.Customer_context.UnionType = avro_dto.Customer_contextUnionTypeEnumAvro_dto_customer_context
    res.Customer_context.Avro_dto_customer_context, err = avro_dto.NewAvro_dto_customer_contextValue(string(*data.CustomerContext))
    if err != nil {
        return avro_dto.Avro_dto{}, fmt.Errorf("failed to map customer_context field: %w", err)
    }
}

1. We need to check if field is filled in.
2. We need to initialize new union for customer context and set union type into customer_contextUnion
3. After we can put our enum inside. I used auto-generated NewAvro_dto_customer_contextValue function, and checked error value ofc.
4. If you want to keep continue the process, you can just set CustomerContext field into nil.