Migrator

Migrator is an automatic migration script creation tool for go.

Only works with MySQL, for now...

---

• Migrator uses GORM struct tags to parse Go struct fields into MySQL columns.
• You can check the GORM Official Docs to learn more about these GORM tags.
• Migrator uses versioned migration database approach. You can use golang-migrate to apply migrations to database

---

What migrator can do?

Migrator can handle given scenarios and create related migration scripts for you:

Warning

Migrator DELETES unused tables, columns and constraints from database

• Creating and deleting table
• Adding, deleting and modifying columns
• Passing default values for colums. GORM docs
• Creating, deleting and modifying one-to-one or one-to-many foreign key references One-to-one, One-to-many
• Creating, deleting and modifying unique keys.
• Creating, deleting composite unique keys.
• Creating composite primary keys. GORM docs
• Renaming primary key

TODO:

• Creating indexes
• Renaming columns
• Type checking for default values
• General error checking

---

Example

• You can add this into your main and run it by go run . -migrate to create migration scripts in the given destination. If -dry-run argument is passed along with the -migrate, migrator prints the migration script and exits.
• To be able to create foreign key relations, you must pass referenced model into migrator.MigrateAndSave method before the model that has foreign key

main.go

var migrateFlag = flag.Bool("migrate", false, "creates migration scripts")
var dryRun = flag.Bool("dry-run", false, "Print the content of migration instead of creating the file")

func main() {
	flag.Parse()

	// If migrate flag is passed, create migration scripts without starting the server
	if *migrateFlag {
		dsn := fmt.Sprintf("name:password@tcp(host:port)/DBName")
		migrator := migrator.NewMigrator(dsn, "DBName")
		defer migrator.DB.Close()

		migrator.MigrateAndSave(*dryRun, "./database/migrations", // You can pass any destination to save migration scripts
			User{},
			Company{},
			// You can add more models
			...
		)

		// Close the program after migration script created
		os.Exit(0)
	}

	// Other main codes
	...

}