migrations

README

Migrations

Every migration is encapsulated to prevent type collisions now and in the future.

Each migration contains two packages, the root package which includes the definitions of the types being moved to, and the old package which contains the previous definition of each type.

Fields that remain unchanged during a migration can be easily handled by marking their type as migration0.Unchanged in both the old and new definition of each type.

When introducing a new type, be sure to include its JSON Marshaling and Unmarshaling behavior if it is customized.

Example

package old // previous type structure

type RunResult struct {
	JobRunID     migration0.Unchanged `json:"jobRunId" storm:"id"`
	Amount       *big.Int             `json:"amount,omitempty"` // old type
}

package migration1

type RunResult struct {
	JobRunID     migration0.Unchanged `json:"jobRunId" storm:"id"`
	Amount       *assets.Link         `json:"amount,omitempty"` // new type
}

One can now deserialize old.RunResult, convert to migration1.RunResult, and then persist the new instance to bolt.

package migration1

type RunResult struct {
	JobRunID     migration0.Unchanged `json:"jobRunId" storm:"id"`
	Amount       *assets.Link         `json:"amount,omitempty"` // new type
}

func (m Migration) Migrate(orm *orm.ORM) error {
	var jrs []old.JobRun
	if err := orm.All(&jrs); err != nil {
		return fmt.Errorf("failed migration1: %v", err)
	}

	tx, err := orm.Begin(true)
	if err != nil {
		return fmt.Errorf("error starting transaction: %+v", err)
	}
	defer tx.Rollback()

	for _, jr := range jrs {
		jr2 := m.Convert(jr) // Convert to migration2.JobRun
		if err := tx.Save(&jr2); err != nil {
			return err
		}
	}

	return tx.Commit()
}

Add to global registry

store/migrations/migrate.go

func init() {
	registerMigration(migration1.Migration{})
	registerMigration(migration2.Migration{})
	registerMigration(migration<newMigration>.Migration{})
}

Helpers

Run cldev migration to generate a migration template, prepopulated with a current timestamp.

• Be sure to add your new migration to the list of migrations in store/migrations/migrate.go:

Documentation

Index

• func Migrate(orm *orm.ORM) error
• type MigrationTimestamp

Functions

func Migrate

func Migrate(orm *orm.ORM) error

Migrate iterates through available migrations, running and tracking migrations that have not been run.

Types

type MigrationTimestamp

type MigrationTimestamp struct {
	Timestamp string `json:"timestamp" storm:"id"`
}

MigrationTimestamp tracks already run and available migrations.