可以使用golang-migrate与Go的嵌入功能一起使用吗？

huangapple
go评论120阅读模式
英文:

Can you use golang-migrate with go's embed function?

问题

我正在尝试使用golang-migrate将一个SQL文件迁移到我的PostgreSQL数据库中。我可能做错了什么，但当我运行迁移命令时，它显示找不到模式：

  1. $ go run ./cmd/migrate
  2. 2022/04/05 16:20:29 no scheme
  3. exit status 1

以下是代码：

  1. // package dbschema contains the database schema, migrations, and seeding data.
  3. package dbschema
  5. import (
  6. 	"context"
  7. 	_ "embed" // 调用init函数。
  8. 	"fmt"
  9. 	"log"
  11. 	"github.com/golang-migrate/migrate/v4"
  12. 	"github.com/golang-migrate/migrate/v4/database/postgres"
  13. 	"github.com/jmoiron/sqlx"
  14. 	"github.com/jonleopard/bootstrap/pkg/sys/database"
  15. 	_ "github.com/lib/pq"
  16. )
  18. var (
  19. 	//go:embed sql/000001_schema.up.sql
  20. 	schemaDoc string
  22. 	//go:embed sql/seed.sql
  23. 	seedDoc string
  24. )
  26. // Migrate尝试使用此包中定义的迁移将数据库的模式更新到最新状态。
  27. func Migrate(ctx context.Context, db *sqlx.DB) error {
  28. 	if err := database.StatusCheck(ctx, db); err != nil {
  29. 		return fmt.Errorf("status check database: %w", err)
  30. 	}
  32. 	driver, err := postgres.WithInstance(db.DB, &postgres.Config{})
  33. 	if err != nil {
  34. 		return fmt.Errorf("Construct Migrate driver: %w", err)
  35. 	}
  37. 	m, err := migrate.NewWithDatabaseInstance(schemaDoc, "postgres", driver)
  38. 	if err != nil {
  39. 		log.Fatal(err)
  40. 	}
  42. 	return m.Up()
  43. }

希望这可以帮助到你。

英文:

I'm trying to use golang-migrate to migrate a sql file into my postgresql database. I'm likely doing this wrong, but when I run the command to migrate it says that no scheme is found:

  1.  $ go run ./cmd/  migrate
  2. 2022/04/05 16:20:29 no scheme
  3. exit status 1

Here is the code:

  1.   // package dbschema contains the database schema, migrations, and seeding data.
  3.     package dbschema
  4.     
  5.     import (
  6.     	"context"
  7.     	_ "embed" // Calls init function.
  8.     	"fmt"
  9.     	"log"
  10.     
  11.     	"github.com/golang-migrate/migrate/v4"
  12.     	"github.com/golang-migrate/migrate/v4/database/postgres"
  13.     	"github.com/jmoiron/sqlx"
  14.     	"github.com/jonleopard/bootstrap/pkg/sys/database"
  15.     	_ "github.com/lib/pq"
  16.     )
  17.     
  18.     var (
  19.     	//go:embed sql/000001_schema.up.sql
  20.     	schemaDoc string
  21.     
  22.     	//go:embed sql/seed.sql
  23.     	seedDoc string
  24.     )
  25.     
  26.     // Migrate attempts to bring the schema for db up to date with the migrations
  27.     // defined in this package.
  28.     func Migrate(ctx context.Context, db *sqlx.DB) error {
  29.     	if err := database.StatusCheck(ctx, db); err != nil {
  30.     		return fmt.Errorf("status check database: %w", err)
  31.     	}
  32.     
  33.     	driver, err := postgres.WithInstance(db.DB, &postgres.Config{})
  34.     	if err != nil {
  35.     		return fmt.Errorf("Construct Migrate driver: %w", err)
  36.     	}
  37.     
  38.     	m, err := migrate.NewWithDatabaseInstance(schemaDoc, "postgres", driver)
  39.     	if err != nil {
  40.     		log.Fatal(err)
  41.     	}
  42.     
  43.     	return m.Up()
  44.     }

答案1

得分: 6

NewWithDatabaseInstance的定义如下：

  1. func NewWithDatabaseInstance(sourceURL string, databaseName string, databaseInstance database.Driver) (*Migrate, error)

所以第一个参数是一个URL，而你传入的是脚本本身。NewWithDatabaseInstance调用了SchemeFromURL，这就是你看到的错误的原因（因为你传入的URL不包含:）。URL由一个“scheme”后跟:，然后是其他信息组成。

要使用golang-migrate和embed，请参考文档中的示例：

  1. //go:embed testdata/migrations/*.sql
  2. var fs embed.FS
  4. func main() {
  5. 	d, err := iofs.New(fs, "testdata/migrations")
  6. 	if err != nil {
  7. 		log.Fatal(err)
  8. 	}
  9. 	m, err := migrate.NewWithSourceInstance("iofs", d, "postgres://postgres@localhost/postgres?sslmode=disable")
  10. 	if err != nil {
  11. 		log.Fatal(err)
  12. 	}
  13. 	err = m.Up()
  14. 	if err != nil {
  15. 		// ...
  16. 	}
  17. 	// ...
  18. }

你会注意到，这里传入的是一个文件夹（作为embed.FS），而不是单个文件。这是因为golang-migrate设计用于应用多个迁移，而不仅仅是对数据库运行单个脚本。你应该可以使用类似以下的代码：

  1. //go:embed sql/*.sql
  2. var schemaFs embed.FS
  3. ...
  4. d, err := iofs.New(fs, "sql") // 从sql文件夹获取迁移
  5. if err != nil {
  6. 	log.Fatal(err)
  7. }
  8. m, err := migrate.NewWithInstance("iofs", d, "postgres", driver)
英文:

The definition of NewWithDatabaseInstance is:

  1. func NewWithDatabaseInstance(sourceURL string, databaseName string, databaseInstance database.Driver) (*Migrate, error)

So the first parameter is a URL and you are passing in the script itself. NewWithDatabaseInstance calls SchemeFromURL which is what generates the error you are seeing (because the url you are passing does not contain a :). A URL consists of a "scheme" followed by : and then other info.

To use golang-migrate with embed see the example in the docs:

  1. //go:embed testdata/migrations/*.sql
  2. var fs embed.FS
  4. func main() {
  5. 	d, err := iofs.New(fs, "testdata/migrations")
  6. 	if err != nil {
  7. 		log.Fatal(err)
  8. 	}
  9. 	m, err := migrate.NewWithSourceInstance("iofs", d, "postgres://postgres@localhost/postgres?sslmode=disable")
  10. 	if err != nil {
  11. 		log.Fatal(err)
  12. 	}
  13. 	err = m.Up()
  14. 	if err != nil {
  15. 		// ...
  16. 	}
  17. 	// ...
  18. }

You will note that this passes in a folder (as an embed.FS) rather than a single file. This is because golang-migrate is designed to apply multiple migrations rather than just running a single script against the database. You should be able to use something like:

  1. //go:embed sql/*.sql
  2. var schemaFs embed.FS
  3. ...
  4. d, err := iofs.New(fs, "sql") // Get migrations from sql folder
  5. if err != nil {
  6. 	log.Fatal(err)
  7. }
  8. m, err := migrate.NewWithInstance("iofs", d, "postgres", driver)

huangapple
  • 本文由 发表于 2022年4月6日 07:26:21
  • 转载请务必保留本文链接：https://go.coder-hub.com/71759491.html
  • go
  • golang-migrate
  • postgresql
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