Gorm database migration

Simple library to take advantage of the gorm's migration API.

Choices

• It only applies migrations. It's up to you to chose when to apply each operation.
• Any failure cancels every single change (including the one to the migrations listing table)
• There are no consistency checks between migrations. ALl migrations will be applied as long as they are after the current migration.

Known issues

• The column dropping operation doesn't work in SQLite because this library performs all the changes within a transaction, and the SQLite Migrator's DropColumn works by creating a transaction in pure-SQL with a BEGIN when a sub-transaction using a SAVEPOINT is necessary here.

How to use

import (
	"gorm.io/gorm"
	migrate "github.com/fclairamb/gorm-migrate"
)

func performMigrations(db *gorm.DB) error {
    
    steps := []*migrate.MigrationStep{
        {
            Name: "2020-09-12 01:00",
            Up: func(db *gorm.DB) error {
                return db.Migrator().AutoMigrate(&User{})
            },
            Down: func(db *gorm.DB) error {
                if db.Migrator().HasTable(&User{}) {
                    return db.Migrator().DropTable(&User{})
                }
                return nil
            },
        },
        {
            Name: "2020-09-12 02:00",
            Up: func(db *gorm.DB) error {
                return nil
            },
            Down: func(db *gorm.DB) error {
                return nil
            },
        },
    }
    
    if nb, err := migrate.Migrate(db, steps, migrate.UpFull); err != nil {
        return err
    } else if nb > 0 {
        log.Printf("Performed %d migrations !\n", nb)
    }
    return nil
}