package bolt import ( "fmt" "github.com/boltdb/bolt" ) // SchemaVersionBucket stores ids of completed migrations var SchemaVersionBucket = []byte("SchemaVersions") // IsMigrationComplete checks for the presence of a particular migration id func IsMigrationComplete(db bolt.DB, id string) (bool, error) { complete := false if err := db.View(func(tx *bolt.Tx) error { migration := tx.Bucket(SchemaVersionBucket).Get([]byte(id)) if migration != nil { complete = true } return nil }); err != nil { // If there's an error, represent this migration as complete // so that future downstream code doesn't run it return true, err } return complete, nil } // MarkMigrationAsComplete adds the migration id to the schema bucket func MarkMigrationAsComplete(db bolt.DB, id string) error { if err := db.Update(func(tx *bolt.Tx) error { return tx.Bucket(SchemaVersionBucket).Put([]byte(id), []byte{}) }); err != nil { return err } return nil } // Migration defines a database state/schema transition // ID: After the migration is run, this id is stored in the database. // We don't want to run a state transition twice // Up: The forward-transition function. After a version upgrade, a number // of these will run on database startup in order to bring a user's // schema in line with struct definitions in the new version. // Down: The backward-transition function. We don't expect these to be // run on a user's database -- if the user needs to rollback // to a previous version, it will be easier for them to replace // their current database with one of their backups. The primary // purpose of a Down() function is to help contributors move across // development branches that have different schema definitions. type Migration struct { ID string Up func(db bolt.DB) error Down func(db bolt.DB) error } // Migrate runs one migration's Up() function, if it has not already been run func (m Migration) Migrate(db bolt.DB) error { _, err := IsMigrationComplete(db, m.ID) if err != nil { return err } // if complete { // return nil // } fmt.Println("Running a migration!") // client.logger.Info("Running migration (", m.ID, ")") if err = m.Up(db); err != nil { return err } return MarkMigrationAsComplete(db, m.ID) } // MigrateAll iterates through all known migrations and runs them in order func MigrateAll(db bolt.DB) error { for _, m := range migrations { err := m.Migrate(db) if err != nil { return err } } return nil } var migrations = []Migration{ changeIntervalToDuration, }