How to do Migration using golang-migrate

huangapple
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英文:

How to do Migration using golang-migrate

问题

我有一个使用golang-migrate/migrate和PostgreSQL数据库的简单应用程序。然而，当我调用Migration函数时，我认为我的migrate.New()中的sourceURL或databaseURL是无效的内存地址或空指针，因此出现了错误。

但我不确定为什么我的sourceURL或databaseURL会引发错误-我将sourceURL存储为file:///database/migration，这是存储我的SQL文件的目录，将databaseURL存储为postgres://postgres:postgres@127.0.0.1:5432/go_graphql?sslmode=disable，这在我的Makefile中定义。

我的Makefile如下所示：

  1. migrate:
  2. 	migrate -source file://database/migration \
  3. 			-database postgres://postgres:postgres@127.0.0.1:5432/go_graphql?sslmode=disable up
  5. rollback:
  6. 	migrate -source file://database/migration \
  7. 			-database postgres://postgres:postgres@127.0.0.1:5432/go_graphql?sslmode=disable down
  9. drop:
  10. 	migrate -source file://database/migration \
  11. 			-database postgres://postgres:postgres@127.0.0.1:5432/go_graphql?sslmode=disable drop
  13. migration:
  14. 	migrate create -ext sql -dir database/migration go_graphql
  16. run:
  17. 	go run main.go

然后，我的main.go如下所示。

  1. func main() {
  2. 	ctx := context.Background()
  4. 	config := config.New()
  6. 	db := pg.New(ctx, config)
  7. 	println("HEL")
  9. 	if err := db.Migration(); err != nil {
  10. 		log.Fatal(err)
  11. 	}
  13. 	fmt.Println("Server started")
  14. }

当我在main.go中调用db.Migration时，我遇到了错误。

  1. func (db *DB) Migration() error {
  3. 	m, err := migrate.New("file:///database/migration/", "postgres://postgres:postgres@127.0.0.1:5432/go_graphql?sslmode=disable"))
  4. 	println(m)
  5. 	if err != nil {
  6.         // **我在这里遇到错误！！**
  7. 		return fmt.Errorf("迁移时发生错误")
  8. 	}
  9. 	if err := m.Up(); err != nil && err != migrate.ErrNoChange {
  10. 		return fmt.Errorf("迁移上时发生错误：%v", err)
  11. 	}
  13. 	log.Println("迁移完成！")
  14. 	return err
  15. }

这是我的config.go。DATABASE_URL与PostgreSQL URL相同。

  1. type database struct {
  2. 	URL string
  3. }
  5. type Config struct {
  6. 	Database database
  7. }
  9. func New() *Config {
  10. 	godotenv.Load()
  12. 	return &Config{
  13. 		Database: database{
  14. 			URL: os.Getenv("DATABASE_URL"),
  15. 		},
  16. 	}
  17. }
英文:

I have a simple application using golang-migrate/migrate with postgresql database. However, I think I receive an error when I call Migration function since my either sourceURL or databaseURL in migrate.New() is invalid memory address or nil pointer.

But I am not sure why my sourceURL or databaseURL is causing error - I store sourceURL as file:///database/migration which is the directory where my sql file is stored, databaseURL as postgres://postgres:postgres@127.0.0.1:5432/go_graphql?sslmode=disable which is defined in my Makefile.

My Makefile is like this

  1. migrate:
  2. 	migrate -source file://database/migration \
  3. 			-database postgres://postgres:postgres@127.0.0.1:5432/go_graphql?sslmode=disable up
  5. rollback:
  6. 	migrate -source file://database/migration \
  7. 			-database postgres://postgres:postgres@127.0.0.1:5432/go_graphql?sslmode=disable down
  9. drop:
  10. 	migrate -source file://database/migration \
  11. 			-database postgres://postgres:postgres@127.0.0.1:5432/go_graphql?sslmode=disable drop
  13. migration:
  14. 	migrate create -ext sql -dir database/migration go_graphql
  16. run:
  17. 	go run main.go

Then, my main.go is like below.

  1. func main() {
  2. 	ctx := context.Background()
  4. 	config := config.New()
  6. 	db := pg.New(ctx, config)
  7. 	println("HEL")
  9. 	if err := db.Migration(); err != nil {
  10. 		log.Fatal(err)
  11. 	}
  13. 	fmt.Println("Server started")
  14. }

I got error when I call db.Migration in main.go

  1. func (db *DB) Migration() error {
  3. 	m, err := migrate.New("file:///database/migration/", "postgres://postgres:postgres@127.0.0.1:5432/go_graphql?sslmode=disable"))
  4. 	println(m)
  5. 	if err != nil {
  6.         // **I get error here!!**
  7. 		return fmt.Errorf("error happened when migration")
  8. 	}
  9. 	if err := m.Up(); err != nil && err != migrate.ErrNoChange {
  10. 		return fmt.Errorf("error when migration up: %v", err)
  11. 	}
  13. 	log.Println("migration completed!")
  14. 	return err
  15. }

Here is my config.go. DATABASE_URL is the same as postgres URL

  1. type database struct {
  2. 	URL string
  3. }
  5. type Config struct {
  6. 	Database database
  7. }
  9. func New() *Config {
  10. 	godotenv.Load()
  12. 	return &Config{
  13. 		Database: database{
  14. 			URL: os.Getenv("DATABASE_URL"),
  15. 		},
  16. 	}
  17. }

答案1

得分: 4

根据你在评论中提供的错误信息“error happened when migration source driver: unknown driver 'file' (forgotten import?)”，我可以告诉你，正如错误信息所述，你忘记导入file：

  1. import (
  2.   ....
  3.   _ "github.com/golang-migrate/migrate/v4/source/file"
  4. )

你可以在https://github.com/golang-migrate/migrate#use-in-your-go-project的“Want to use an existing database client?”部分中找到一个示例。

英文:

With the error you posted in the comments error happened when migration source driver: unknown driver 'file' (forgotten import?) I can tell you that, as stated, you forgot to import file:

  1. import (
  2.   ....
  3.   _ "github.com/golang-migrate/migrate/v4/source/file"
  4. )

You can see an example in https://github.com/golang-migrate/migrate#use-in-your-go-project in the section Want to use an existing database client?

huangapple
  • 本文由 发表于 2021年9月4日 17:31:03
  • 转载请务必保留本文链接：https://go.coder-hub.com/69054061.html
  • go
  • golang-migrate
  • postgresql
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