how to implement domain driven design in golang

For example, I want to build a todo list application.

Introduction

I want to design a product with frontend, backend, and infrastructure. So I want to build a microservice for the product. The first question is that I will need to know how to split a service, so I want to use Domain-Driven Design to break down each service.

Product description

Functional

Main

• add task by title
• list all tasks
• delete task
• modify task

Architecture design

Domain-Driven Design

• Account: define a user
• Task: as a representation of all tickets

graph
    account
    task

Implementation

Project layout

I follow Standard Go Project Layout

Layered architecture

graph
    user:((user)) --> 
    presentation:(presentation layer) -->
    biz:(business layer) -->
    repo:(repository layer) -->
    data:[(data source)]

Presentation layer

The presentation layer is the highest layer of the software. It can be a Restful even Grpc, graphQL, and CLI.

folder layout:

flowchart TD
    root-->/cmd
    /cmd-->/restful
    /restful-->/account/main.go
    /restful-->/task/main.go
    /cmd-->/grpc
    /grpc-->account1:["/account/main.go"]
    /cmd-->/cronjob
    /cmd-->/graphql

Business layer

As the name of this layer, most of the logic of the application will be placed in this layer. For example, if we have TaskBiz we expect that create, complete, and delete task happens there like in a real life. he Biz layer allows developers to design applications that support multiple user interfaces, this minimizes the chances of needless code duplication. Usually, this layer is divided into smaller pieces that are easy to manage.

folder layout:

flowchart TD
    root-->/internal/app/domain/account/biz/impl.go
    root-->/pkg/entity/domain/account/biz/interface.go

Repository layer

The repository layer is the layer that implements communication with the data source (usually a database). No matter if we’re fetching the data from the DB or saving/modifying objects, it’s the place where SQL queries or ORM operations should be placed.

folder layout: internal/app/domain/account/biz/repo/interface.go

Example

Todo app