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resotto
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Description

Clean Boilerplate of Go, Domain-Driven Design, Clean Architecture, Gin and GORM.

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Goilerplate

Clean Boilerplate of Go, Domain-Driven Design, Clean Architecture, Gin and GORM.


What is Goilerplate?

  • Good example of Go with Clean Architecture.
  • Rocket start guide of Go, Domain-Driven Design, Clean Architecture, Gin, and GORM.

Who is the main user of Goilerplate?

  • All kinds of Gophers (newbie to professional).

Why Goilerplate?

  • Easy-applicable boilerplate in Go.

Note

  • Default application/test code is trivial because you will write cool logic.
  • Public API of bitbank, which is bitcoin exchange located in Tokyo, is used for some endpoints by default.

Table of Contents

Getting Started

go get -u github.com/resotto/goilerplate        # might take few minutes
cd ${GOPATH}/src/github.com/resotto/goilerplate
go run cmd/app/main.go                          # from root directory
open http://0.0.0.0:8080

go get
Goilerplate via SSH

go get
fetches GitHub repository via HTTPS by default. So you might fail
go get
:
~  > go get -u github.com/resotto/goilerplate
# cd .; git clone -- https://github.com/resotto/goilerplate /Users/resotto/go/src/github.com/resotto/goilerplate
Cloning into '/Users/resotto/go/src/github.com/resotto/goilerplate'...
fatal: could not read Username for 'https://github.com': terminal prompts disabled
package github.com/resotto/goilerplate: exit status 128

If you

go get
GitHub repository via SSH, please run following command:
git config --global [email protected]:.insteadOf https://github.com/

And then, please try Getting Started again.

Endpoints

  • With Template
    • GET /
    • NOTICE: Following path is from CURRENT directory, so please run Gin from root directory.
      go
      r.LoadHTMLGlob("internal/app/adapter/view/*")
      
  • With Public API of bitbank
    • GET /ticker
    • GET /candlestick
    • NOTICE: This works from 0AM ~ 3PM (UTC) due to its API constraints.
  • With PostgreSQL

Package Structure

.
├── LICENSE
├── README.md
├── build                                     # Packaging and Continuous Integration
│   ├── Dockerfile
│   └── init.sql
├── cmd                                       # Main Application
│   └── app
│       └── main.go
├── internal                                  # Private Codes
│   └── app
│       ├── adapter
│       │   ├── controller.go                 # Controller
│       │   ├── postgresql                    # Database
│       │   │   ├── conn.go
│       │   │   └── model                     # Database Model
│       │   │       ├── card.go
│       │   │       ├── cardBrand.go
│       │   │       ├── order.go
│       │   │       ├── parameter.go
│       │   │       ├── payment.go
│       │   │       └── person.go
│       │   ├── repository                    # Repository Implementation
│       │   │   ├── order.go
│       │   │   └── parameter.go
│       │   ├── service                       # Application Service Implementation
│       │   │   └── bitbank.go
│       │   └── view                          # Templates
│       │       └── index.tmpl
│       ├── application
│       │   ├── service                       # Application Service Interface
│       │   │   └── exchange.go
│       │   └── usecase                       # Usecase
│       │       ├── addNewCardAndEatCheese.go
│       │       ├── ohlc.go
│       │       ├── parameter.go
│       │       ├── ticker.go
│       │       └── ticker_test.go
│       └── domain
│           ├── factory                       # Factory
│           │   └── order.go
│           ├── order.go                      # Entity
│           ├── parameter.go
│           ├── parameter_test.go
│           ├── person.go
│           ├── repository                    # Repository Interface
│           │   ├── order.go
│           │   └── parameter.go
│           └── valueobject                   # ValueObject
│               ├── candlestick.go
│               ├── card.go
│               ├── cardbrand.go
│               ├── pair.go
│               ├── payment.go
│               ├── ticker.go
│               └── timeunit.go
└── testdata                                  # Test Data
    └── exchange_mock.go

#fffacd Domain Layer

  • The core of Clean Architecture. It says "Entities".

#f08080 Application Layer

  • The second layer from the core. It says "Use Cases".

#98fb98 Adapter Layer

  • The third layer from the core. It says "Controllers / Gateways / Presenters".

#87cefa External Layer

  • The fourth layer from the core. It says "Devices / DB / External Interfaces / UI / Web".
    • We DON'T write much codes in this layer.

The Clean Architecture

How to Cross the Border of Those Layers

In Clean Architecture, there is The Dependency Rule:

This rule says that source code dependencies can only point inwards. Nothing in an inner circle can know anything at all about something in an outer circle.

In other words, Dependency Injection is required to follow this rule.

Therefore, please follow the next four steps:

  1. Define Interface
  2. Take Argument as Interface and Call Functions of It
  3. Implement It
  4. Inject Dependency

Here, I pick up the example of Repository.

Repository

.
└── internal
    └── app
        ├── adapter
        │   ├── controller.go    # 4. Dependency Injection
        │   └── repository
        │       └── parameter.go # 3. Implementation
        ├── application
        │   └── usecase
        │       └── parameter.go # 2. Interface Function Call
        └── domain
            ├── parameter.go
            └── repository
                └── parameter.go # 1. Interface
  1. Interface at Domain Layer:
package repository

import "github.com/resotto/goilerplate/internal/app/domain"

// IParameter is interface of parameter repository type IParameter interface { Get() domain.Parameter }

  1. Usecase at Application Layer:
package usecase

// NOTICE: This usecase DON'T depend on Adapter layer import ( "github.com/resotto/goilerplate/internal/app/domain" "github.com/resotto/goilerplate/internal/app/domain/repository" )

// Parameter is the usecase of getting parameter func Parameter(r repository.IParameter) domain.Parameter { return r.Get() }

  1. Implementation at Adapter Layer:
package repository

// Parameter is the repository of domain.Parameter type Parameter struct{}

// Get gets parameter func (r Parameter) Get() domain.Parameter { db := postgresql.Connection() var param model.Parameter result := db.First(&param, 1) if result.Error != nil { panic(result.Error) } return domain.Parameter{ Funds: param.Funds, Btc: param.Btc, } }

  1. Dependency Injection at Controller of Adapter Layer:
package adapter

// NOTICE: Controller depends on INNER CIRCLE so it points inward (The Dependency Rule) import ( "github.com/gin-gonic/gin" "github.com/resotto/goilerplate/internal/app/adapter/repository" "github.com/resotto/goilerplate/internal/app/application/usecase" )

var ( parameterRepository = repository.Parameter{} )

func (ctrl Controller) parameter(c *gin.Context) { parameter := usecase.Parameter(parameterRepository) // Dependency Injection c.JSON(200, parameter) }

Implementation of Application Service is also the same.

Dependency Injection

In Goilerplate, dependencies are injected manually.

  • NOTICE: If other DI tool in Go doesn't become some kind of application framework, it will also be acceptable.

There are two ways of passing dependencies:

  • with positional arguments
  • with keyword arguments

With Positional Arguments

First, define usecase with arguments of interface type.

package usecase

func Parameter(r repository.IParameter) domain.Parameter { // Take Argument as Interface return r.Get() }

Second, initialize implementation and give it to the usecase.

package adapter

var ( parameterRepository = repository.Parameter{} // Initialize Implementation )

func (ctrl Controller) parameter(c *gin.Context) { parameter := usecase.Parameter(parameterRepository) // Inject Implementation to Usecase c.JSON(200, parameter) }

With Keyword Arguments

First, define argument struct and usecase taking it.

package usecase

// OhlcArgs are arguments of Ohlc usecase type OhlcArgs struct { E service.IExchange // Interface P valueobject.Pair T valueobject.Timeunit }

func Ohlc(a OhlcArgs) []valueobject.CandleStick { // Take Argument as OhlcArgs return a.E.Ohlc(a.P, a.T) }

And then, initialize the struct with keyword arguments and give it to the usecase.

package adapter

var ( bitbank = service.Bitbank{} // Implementation )

func (ctrl Controller) candlestick(c *gin.Context) { args := usecase.OhlcArgs{ // Initialize Struct with Keyword Arguments E: bitbank, // Passing the implementation P: valueobject.BtcJpy, T: valueobject.OneMin, } candlestick := usecase.Ohlc(args) // Give Arguments to Usecase c.JSON(200, candlestick) }

Global Injecter Variable

In manual DI, implementation initialization cost will be expensive.
So, let's use global injecter variable in order to initialize them only once.

package adapter

var ( bitbank = service.Bitbank{} // Injecter Variable parameterRepository = repository.Parameter{} orderRepository = repository.Order{} )

func (ctrl Controller) ticker(c *gin.Context) { pair := valueobject.BtcJpy ticker := usecase.Ticker(bitbank, pair) // DI by passing bitbank c.JSON(200, ticker) }

How to start with Goilerplate

With Goilerplate, you can start your project smoothly.

For explanation, let's create simple "CR" part of CRUD of following specifications with Goilerplate.

Specifications: - There are three entities such as Customer, Product, and Order. - Order aggregates Customer and Product (Order is Aggregate Root). - There is only one usecase to create an order.

NOTICE: - For convenience, the minimum codes are shown here. - For convenience, there are no test codes in this explanation.

First of all, please prepare .go files with following package layout.

Package Layout

.
└── internal
    └── app
        ├── adapter
        │   ├── controller.go                 # Controller
        │   └── repository                    # Repository Implementation
        │       ├── customer.go
        │       ├── product.go
        │       └── order.go
        ├── application
        │   └── usecase                       # Usecase
        │       └── createOrder.go
        └── domain
            ├── customer.go                   # Entity
            ├── product.go                    # Entity
            ├── order.go                      # Entity
            └── repository                    # Repository Interface
                ├── customer.go
                ├── product.go
                └── order.go

Define Entities

Secondly, let's create entities, Customer, Product, and Order.

// customer.go
package domain

type Customer struct { ID string Name string }

// product.go
package domain

type Product struct { ID string Price int }

// order.go
package domain

type Order struct { ID string Customer Customer Product Product }

Define Repository Interfaces

After defining entities, let's prepare their repositories in

domain
package.
// customer.go
package repository

type ICustomer interface { Get(id string) domain.Customer }

// product.go
package repository

type IProduct interface { Get(id string) domain.Product }

// order.go
package repository

type IOrder interface { Save(order Order) }

Define Usecase

And then, let's prepare the usecase of creating order.

// createOrder.go
package usecase

import ( "domain" // simplified for convenience "domain/repository" // simplified for convenience )

type CreateOrderArgs struct { CustomerID string ProductID string CustomerRepository repository.ICustomer ProductRepository repository.IProduct OrderRepository repository.IOrder }

func CreateOrder(args CreateOrderArgs) domain.Order { customer := args.CustomerRepository.Get(args.CustomerID) product := args.ProductRepository.Get(args.ProductID) order := domain.Order{ ID: "123", Customer: customer, Product: product, } args.OrderRepository.Save(order) return order }

Define Repository Implementations

After preparing the usecase, let's implement repository interfaces in

adapter
package.

However, this part is omitted here for convenience.

// order.go
package repository

import ( "domain" // simplified for convenience )

type Order struct{}

func (o Order) Save(order domain.Order) { // omitted here for convenience }

Define Controller

Finally, let's define controller to call the usecase of creating an order.

// controller.go
package adapter

import ( "repository" // simplified for convenience "usecase" // simplified for convenience

"github.com/gin-gonic/gin"

)

var ( customerRepository = repository.Customer{} productRepository = repository.Product{} orderRepository = repository.Order{} )

type Controller struct{}

func Router() *gin.Engine { r := gin.Default() ctrl := Controller{} r.POST("/order", ctrl.createOrder) return r }

func (ctrl Controller) createOrder(c *gin.Context) { customerID := c.Query("customerId") productID := c.Query("productId") args := usecase.CreateOrderArgs{ CustomerID: customerID, ProductID: productID, CustomerRepository: customerRepository, ProductRepository: productRepository, OrderRepository: orderRepository, } order := usecase.CreateOrder(args) c.JSON(200, order) }

That's it!

Testing

~/go/src/github.com/resotto/goilerplate (master) > go test ./internal/app/...
?       github.com/resotto/goilerplate/internal/app/adapter     [no test files]
?       github.com/resotto/goilerplate/internal/app/adapter/postgresql  [no test files]
?       github.com/resotto/goilerplate/internal/app/adapter/postgresql/model    [no test files]
?       github.com/resotto/goilerplate/internal/app/adapter/repository  [no test files]
?       github.com/resotto/goilerplate/internal/app/adapter/service     [no test files]
?       github.com/resotto/goilerplate/internal/app/application/service [no test files]
ok      github.com/resotto/goilerplate/internal/app/application/usecase 0.204s
ok      github.com/resotto/goilerplate/internal/app/domain      0.273s
?       github.com/resotto/goilerplate/internal/app/domain/factory      [no test files]
?       github.com/resotto/goilerplate/internal/app/domain/repository   [no test files]
?       github.com/resotto/goilerplate/internal/app/domain/valueobject  [no test files]

There are two rules:

  • Name of the package where test code included is
    xxx_test
    .
  • Place mocks on
    testdata
    package.

Test Package Structure

.
├── internal
│   └── app
│       ├── application
│       │   └── usecase
│       │       ├── ticker.go      # Usecase
│       │       └── ticker_test.go # Usecase Test
│       └── domain
│           ├── parameter.go       # Entity
│           └── parameter_test.go  # Entity Test
└── testdata
    └── exchange_mock.go           # Mock if needed

Entity

Please write tests in the same directory as where the entity located.

.
└── internal
    └── app
        └── domain
            ├── parameter.go      # Target Entity
            └── parameter_test.go # Test
// parameter_test.go
package domain_test

import ( "testing"

"github.com/resotto/goilerplate/internal/app/domain"

)

func TestParameter(t *testing.T) { tests := []struct { name string funds, btc int expectedfunds, expectedbtc int }{ {"more funds than btc", 1000, 0, 1000, 0}, {"same amount", 100, 100, 100, 100}, {"much more funds than btc", 100000, 20, 100000, 20}, }

for _, tt := range tests {
    tt := tt
    t.Run(tt.name, func(t *testing.T) {
        t.Parallel()
        parameter := domain.Parameter{
            Funds: tt.funds,
            Btc:   tt.btc,
        }
        if parameter.Funds != tt.expectedfunds {
            t.Errorf("got %q, want %q", parameter.Funds, tt.expectedfunds)
        }
        if parameter.Btc != tt.expectedbtc {
            t.Errorf("got %q, want %q", parameter.Btc, tt.expectedbtc)
        }
    })
}

}

Usecase

Please prepare mock on

testdata
package (if needed) and write tests in the same directory as the usecase.
.
├── internal
│   └── app
│       └── application
│           ├── service
│           │   └── exchange.go    # Application Service Interface
│           └── usecase
│               ├── ticker.go      # Target Usecase
│               └── ticker_test.go # Test
└── testdata
    └── exchange_mock.go           # Mock of Application Service Interface
// exchange_mock.go
package testdata

import "github.com/resotto/goilerplate/internal/app/domain/valueobject"

// MExchange is mock of service.IExchange type MExchange struct{}

// Ticker is mock implementation of service.IExchange.Ticker() func (e MExchange) Ticker(p valueobject.Pair) valueobject.Ticker { return valueobject.Ticker{ Sell: "1000", Buy: "1000", High: "2000", Low: "500", Last: "1200", Vol: "20", Timestamp: "1600769562", } }

// Ohlc is mock implementation of service.IExchange.Ohlc() func (e MExchange) Ohlc(p valueobject.Pair, t valueobject.Timeunit) []valueobject.CandleStick { cs := make([]valueobject.CandleStick, 0) return append(cs, valueobject.CandleStick{ Open: "1000", High: "2000", Low: "500", Close: "1500", Volume: "30", Timestamp: "1600769562", }) }

// ticker_test.go
package usecase_test

import ( "testing"

"github.com/resotto/goilerplate/internal/app/application/usecase"
"github.com/resotto/goilerplate/internal/app/domain/valueobject"
"github.com/resotto/goilerplate/testdata"

)

func TestTicker(t *testing.T) { tests := []struct { name string pair valueobject.Pair expectedsell string expectedbuy string expectedhigh string expectedlow string expectedlast string expectedvol string expectedtimestamp string }{ {"btcjpy", valueobject.BtcJpy, "1000", "1000", "2000", "500", "1200", "20", "1600769562"}, }

for _, tt := range tests {
    tt := tt
    t.Run(tt.name, func(t *testing.T) {
        t.Parallel()
        mexchange := testdata.MExchange{} // using Mock
        result := usecase.Ticker(mexchange, tt.pair)
        if result.Sell != tt.expectedsell {
            t.Errorf("got %q, want %q", result.Sell, tt.expectedsell)
        }
        if result.Buy != tt.expectedbuy {
            t.Errorf("got %q, want %q", result.Buy, tt.expectedbuy)
        }
        if result.High != tt.expectedhigh {
            t.Errorf("got %q, want %q", result.High, tt.expectedhigh)
        }
        if result.Low != tt.expectedlow {
            t.Errorf("got %q, want %q", result.Low, tt.expectedlow)
        }
        if result.Last != tt.expectedlast {
            t.Errorf("got %q, want %q", result.Last, tt.expectedlast)
        }
        if result.Vol != tt.expectedvol {
            t.Errorf("got %q, want %q", result.Vol, tt.expectedvol)
        }
        if result.Timestamp != tt.expectedtimestamp {
            t.Errorf("got %q, want %q", result.Timestamp, tt.expectedtimestamp)
        }
    })
}

}

Naming Convention

Interface

  • Add prefix
    I
    like
    IExchange
    .
    • NOTICE: If you can distinguish interface from implementation, any naming convention will be acceptable.

Mock

  • Add prefix
    M
    like
    MExchange
    .
    • NOTICE: If you can distinguish mock from production, any naming convention will be acceptable.

File

  • File names can be duplicated.
  • For test, add suffix
    _test
    like
    parameter_test.go
    .
  • For mock, add suffix
    _mock
    like
    exchange_mock.go
    .

Package

With Gochk

Gochk, static dependency analysis tool for go files, empowers Goilerplate so much!

Gochk confirms that codebase follows Clean Architecture The Dependency Rule.

Let's merge Gochk into CI process.

name: test

on: push: branches: - master paths-ignore: - "*/.md" pull_request: branches: - master

jobs: gochk-goilerplate: runs-on: ubuntu-latest container: image: docker://ghcr.io/resotto/gochk:latest steps: - name: Clone Goilerplate uses: actions/[email protected] with: repository: {{ github.repository }} - name: Run Gochk run: | /go/bin/gochk -c=/go/src/github.com/resotto/gochk/configs/config.json

And then, its result is:

Gochk Result in GitHub Actions

With PostgreSQL

First, you pull the docker image

ghcr.io/resotto/goilerplate-pg
from GitHub Container Registry and run container with following command:
docker run -d -it --name pg -p 5432:5432 -e POSTGRES_PASSWORD=postgres ghcr.io/resotto/goilerplate-pg:latest

Then, let's check it out:

open http://0.0.0.0:8080/parameter
open http://0.0.0.0:8080/order

Building Image

If you fail pulling image from GitHub Container Registry, you also can build Docker image from Dockerfile.

cd build
docker build -t goilerplate-pg:latest .
docker run -d -it --name pg -p 5432:5432 -e POSTGRES_PASSWORD=postgres goilerplate-pg:latest

Docker Image

The image you pulled from GitHub Container Registry is built from the simple Dockerfile and init.sql.

FROM postgres

EXPOSE 5432

COPY ./init.sql /docker-entrypoint-initdb.d/

create table parameters (
    id integer primary key,
    funds integer,
    btc integer
);

insert into parameters values (1, 10000, 10);

create table persons ( person_id uuid primary key, name text not null, weight integer );

create table card_brands ( brand text primary key );

create table cards ( card_id uuid primary key, brand text references card_brands(brand) on update cascade );

create table orders ( order_id uuid primary key, person_id uuid references persons(person_id) );

create table payments ( order_id uuid primary key references orders(order_id), card_id uuid references cards(card_id) );

insert into persons values ('f3bf75a9-ea4c-4f57-9161-cfa8f96e2d0b', 'Jerry', 1);

insert into card_brands values ('VISA'), ('AMEX');

insert into cards values ('3224ebc0-0a6e-4e22-9ce8-c6564a1bb6a1', 'VISA');

insert into orders values ('722b694c-984c-4208-bddd-796553cf83e1', 'f3bf75a9-ea4c-4f57-9161-cfa8f96e2d0b');

insert into payments values ('722b694c-984c-4208-bddd-796553cf83e1', '3224ebc0-0a6e-4e22-9ce8-c6564a1bb6a1');

Feedbacks

Feel free to write your thoughts

License

GNU General Public License v3.0.

Author

Resotto

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