Introduction

上一篇我们用 GraphQL 已经有个基本的认识
接着来模拟真实的情境搭配 Database 来使用
这篇主要都是在初始化环境

Sample Code

Setup MySQL database by Docker

https://hub.docker.com/_/mysql
Pull MySQL Image from DockerHub docker pull mysql

Create MySQL database

$ docker exec -it mysql bash$ mysql -u root -p$ CREATE DATABASE hackernews;

Models and migrations

接着我们需要利用 https://github.com/golang-migrate/migrate 这个 Package 来处理 Migrations

依照下列结构创建资料夹

go-graphql-hackernews--internal----pkg------db--------migrations----------mysql

最后所有步骤完成后的资料夹分布

依照指令初始化 migrate package

中间遇到缺少的 dependency 就看 console 指示用 go get 抓下来

$ go get -u github.com/go-sql-driver/mysql$ go build -tags 'mysql' -ldflags="-X main.Version=1.0.0" -o $GOPATH/bin/migrate$ github.com/golang-migrate/migrate/v4/cmd/migrate/$ cd internal/pkg/db/migrations/$ migrate create -ext sql -dir mysql -seq create_users_table$ migrate create -ext sql -dir mysql -seq create_links_table

接着会看到几个创建好的 .sql

在 000001_create_users_table.up.sql 内新增

CREATE TABLE IF NOT EXISTS Users(    ID INT NOT NULL UNIQUE AUTO_INCREMENT,    Username VARCHAR (127) NOT NULL UNIQUE,    Password VARCHAR (127) NOT NULL,    PRIMARY KEY (ID))

在 000002_create_links_table.up.sql 内新增

CREATE TABLE IF NOT EXISTS Links(    ID INT NOT NULL UNIQUE AUTO_INCREMENT,    Title VARCHAR (255) ,    Address VARCHAR (255) ,    UserID INT ,    FOREIGN KEY (UserID) REFERENCES Users(ID) ,    PRIMARY KEY (ID))

cd 回到根目录执行

$ migrate -database mysql://root:dbpass@/hackernews -path internal/pkg/db/migrations/mysql up

在 internal/pkg/db/mysql 新增 mysql.go

package databaseimport ("database/sql"_ "github.com/go-sql-driver/mysql""github.com/golang-migrate/migrate""github.com/golang-migrate/migrate/database/mysql"_ "github.com/golang-migrate/migrate/source/file""log")var Db *sql.DBfunc InitDB() {// Use root:dbpass@tcp(172.17.0.2)/hackernews, if you're using Windows.db, err := sql.Open("mysql", "root:dbpass@tcp(localhost)/hackernews")if err != nil {log.Panic(err)}if err = db.Ping(); err != nil { log.Panic(err)}Db = db}func CloseDB() error {return Db.Close()}func Migrate() {if err := Db.Ping(); err != nil {log.Fatal(err)}driver, _ := mysql.WithInstance(Db, &mysql.Config{})m, _ := migrate.NewWithDatabaseInstance("file://internal/pkg/db/migrations/mysql","mysql",driver,)if err := m.Up(); err != nil && err != migrate.ErrNoChange {log.Fatal(err)}}

改写 server.go

这段我有改写一些，教学的sample直接拿来用会报错，改了几个地方

mysql.go 程式码的 package 改名为 mig，不然会抓不到 importgo get -u github.com/go-chi/chi/v5 抓取需要初始化 HTTP router 的 packagehackernews.XXX() 前缀打错了，改成 graph.XXX()

func main() {port := os.Getenv("PORT")if port == "" {port = defaultPort}router := chi.NewRouter()mig.InitDB()defer mig.CloseDB()mig.Migrate()server := handler.NewDefaultServer(graph.NewExecutableSchema(graph.Config{Resolvers: &graph.Resolver{}}))router.Handle("/", playground.Handler("GraphQL playground", "/query"))router.Handle("/query", server)log.Printf("connect to http://localhost:%s/ for GraphQL playground", port)log.Fatal(http.ListenAndServe(":"+port, router))}

Reference

https://www.howtographql.com/graphql-go/4-database/https://github.com/go-chi/chi