Implemented the Rollback feature.
In most dev/testing environments it is nice to have a way to reset/rollback the entire database. This commit adds this feature in the most basic form; when Rollback() is called, it will rollback ALL migrations that have run leaving the database is a mostly pristine state. There are a few potential issues here. For starters, devs may not always want all migrations to be rolled back. The only current fix is to course in this case is to create a migrator that only contains migrations they want rolled back. Another potential issue is that any migration that doesn't provide a Rollback function will not be rolled back, but there also won't be any errors. A message is printed out when this happens to help avoid some confusion, but I could see this still causing issues. I'm not 100% sure what the best long term solution is, but feel the current version is good enough to move forward since it satisfies my needs.
This commit is contained in:
Jon Calhoun
parent
006e7c7cc3
commit
eee25e8d27
120
sqlx.go
120
sqlx.go
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@ -49,6 +49,41 @@ func (s *Sqlx) Migrate(sqlDB *sql.DB, dialect string) error {
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return nil
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}
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// Rollback will run all rollbacks using the provided db connection.
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func (s *Sqlx) Rollback(sqlDB *sql.DB, dialect string) error {
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db := sqlx.NewDb(sqlDB, dialect)
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s.printf("Creating/checking migrations table...\n")
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err := s.createMigrationTable(db)
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if err != nil {
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return err
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}
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for i := len(s.Migrations) - 1; i >= 0; i-- {
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m := s.Migrations[i]
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if m.Rollback == nil {
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s.printf("Rollback not provided: %v\n", m.ID)
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continue
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}
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var found string
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err := db.Get(&found, "SELECT id FROM migrations WHERE id=$1", m.ID)
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switch err {
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case sql.ErrNoRows:
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s.printf("Skipping rollback: %v\n", m.ID)
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continue
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case nil:
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s.printf("Running rollback: %v\n", m.ID)
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// we need to run the rollback so we continue to code below
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default:
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return fmt.Errorf("looking up rollback by id: %w", err)
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}
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err = s.runRollback(db, m)
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if err != nil {
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return err
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}
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}
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return nil
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}
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func (s *Sqlx) printf(format string, a ...interface{}) (n int, err error) {
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printf := s.Printf
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if printf == nil {
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@ -89,48 +124,89 @@ func (s *Sqlx) runMigration(db *sqlx.DB, m SqlxMigration) error {
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return nil
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}
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func (s *Sqlx) runRollback(db *sqlx.DB, m SqlxMigration) error {
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errorf := func(err error) error { return fmt.Errorf("running rollback: %w", err) }
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tx, err := db.Beginx()
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if err != nil {
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return errorf(err)
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}
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_, err = db.Exec("DELETE FROM migrations WHERE id=$1", m.ID)
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if err != nil {
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tx.Rollback()
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return errorf(err)
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}
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err = m.Rollback(tx)
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if err != nil {
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tx.Rollback()
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return errorf(err)
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}
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err = tx.Commit()
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if err != nil {
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return errorf(err)
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}
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return nil
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}
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// SqlxMigration is a unique ID plus a function that uses a sqlx transaction
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// to perform a database migration step.
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//
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// Note: Long term this could have a Rollback field if we wanted to support
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// that.
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type SqlxMigration struct {
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ID string
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Migrate func(tx *sqlx.Tx) error
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ID string
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Migrate func(tx *sqlx.Tx) error
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Rollback func(tx *sqlx.Tx) error
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}
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// SqlxQueryMigration will create a SqlxMigration using the provided id and
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// query string. It is a helper function designed to simplify the process of
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// creating migrations that only depending on a SQL query string.
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func SqlxQueryMigration(id, query string) SqlxMigration {
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m := SqlxMigration{
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ID: id,
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Migrate: func(tx *sqlx.Tx) error {
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func SqlxQueryMigration(id, upQuery, downQuery string) SqlxMigration {
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queryFn := func(query string) func(tx *sqlx.Tx) error {
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if query == "" {
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return nil
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}
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return func(tx *sqlx.Tx) error {
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_, err := tx.Exec(query)
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return err
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},
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}
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}
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m := SqlxMigration{
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ID: id,
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Migrate: queryFn(upQuery),
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Rollback: queryFn(downQuery),
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}
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return m
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}
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// SqlxFileMigration will create a SqlxMigration using the provided file.
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func SqlxFileMigration(id, filename string) SqlxMigration {
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f, err := os.Open(filename)
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if err != nil {
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// We could return a migration that errors when the migration is run, but I
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// think it makes more sense to panic here.
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panic(err)
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}
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fileBytes, err := ioutil.ReadAll(f)
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if err != nil {
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panic(err)
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}
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m := SqlxMigration{
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ID: id,
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Migrate: func(tx *sqlx.Tx) error {
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func SqlxFileMigration(id, upFile, downFile string) SqlxMigration {
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fileFn := func(filename string) func(tx *sqlx.Tx) error {
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if filename == "" {
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return nil
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}
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f, err := os.Open(filename)
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if err != nil {
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// We could return a migration that errors when the migration is run, but I
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// think it makes more sense to panic here.
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panic(err)
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}
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fileBytes, err := ioutil.ReadAll(f)
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if err != nil {
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panic(err)
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}
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return func(tx *sqlx.Tx) error {
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_, err := tx.Exec(string(fileBytes))
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return err
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},
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}
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}
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m := SqlxMigration{
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ID: id,
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Migrate: fileFn(upFile),
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Rollback: fileFn(downFile),
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}
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return m
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}
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66
sqlx_test.go
66
sqlx_test.go
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@ -33,7 +33,7 @@ func TestSqlx(t *testing.T) {
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return 0, nil
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},
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Migrations: []migrate.SqlxMigration{
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migrate.SqlxQueryMigration("001_create_courses", createCoursesSql),
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migrate.SqlxQueryMigration("001_create_courses", createCoursesSql, ""),
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},
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}
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err := migrator.Migrate(db, "sqlite3")
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@ -54,7 +54,7 @@ func TestSqlx(t *testing.T) {
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return 0, nil
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},
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Migrations: []migrate.SqlxMigration{
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migrate.SqlxQueryMigration("001_create_courses", createCoursesSql),
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migrate.SqlxQueryMigration("001_create_courses", createCoursesSql, ""),
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},
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}
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err := migrator.Migrate(db, "sqlite3")
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@ -73,8 +73,8 @@ func TestSqlx(t *testing.T) {
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return 0, nil
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},
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Migrations: []migrate.SqlxMigration{
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migrate.SqlxQueryMigration("001_create_courses", createCoursesSql),
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migrate.SqlxQueryMigration("002_create_users", createUsersSql),
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migrate.SqlxQueryMigration("001_create_courses", createCoursesSql, ""),
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migrate.SqlxQueryMigration("002_create_users", createUsersSql, ""),
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},
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}
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err = migrator.Migrate(db, "sqlite3")
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@ -95,7 +95,7 @@ func TestSqlx(t *testing.T) {
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return 0, nil
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},
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Migrations: []migrate.SqlxMigration{
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migrate.SqlxFileMigration("001_create_widgets", "testdata/widgets.sql"),
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migrate.SqlxFileMigration("001_create_widgets", "testdata/widgets.sql", ""),
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},
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}
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err := migrator.Migrate(db, "sqlite3")
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@ -107,16 +107,68 @@ func TestSqlx(t *testing.T) {
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t.Fatalf("db.Exec() err = %v; want nil", err)
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}
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})
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t.Run("rollback", func(t *testing.T) {
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db := sqliteInMem(t)
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migrator := migrate.Sqlx{
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Printf: func(format string, args ...interface{}) (int, error) {
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t.Logf(format, args...)
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return 0, nil
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},
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Migrations: []migrate.SqlxMigration{
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migrate.SqlxQueryMigration("001_create_courses", createCoursesSql, dropCoursesSql),
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},
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}
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err := migrator.Migrate(db, "sqlite3")
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if err != nil {
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t.Fatalf("Migrate() err = %v; want nil", err)
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}
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_, err = db.Exec("INSERT INTO courses (name) VALUES ($1) ", "cor_test")
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if err != nil {
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t.Fatalf("db.Exec() err = %v; want nil", err)
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}
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err = migrator.Rollback(db, "sqlite3")
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if err != nil {
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t.Fatalf("Rollback() err = %v; want nil", err)
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}
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var count int
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err = db.QueryRow("SELECT COUNT(id) FROM courses;").Scan(&count)
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if err == nil {
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// Want an error here
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t.Fatalf("db.QueryRow() err = nil; want table missing error")
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}
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// Don't want to test inner workings of lib, so let's just migrate again and verify we have a table now
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err = migrator.Migrate(db, "sqlite3")
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if err != nil {
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t.Fatalf("Migrate() err = %v; want nil", err)
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}
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_, err = db.Exec("INSERT INTO courses (name) VALUES ($1) ", "cor_test")
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if err != nil {
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t.Fatalf("db.Exec() err = %v; want nil", err)
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}
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err = db.QueryRow("SELECT COUNT(*) FROM courses;").Scan(&count)
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if err != nil {
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// Want an error here
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t.Fatalf("db.QueryRow() err = %v; want nil", err)
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}
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if count != 1 {
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t.Fatalf("count = %d; want %d", count, 1)
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}
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})
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}
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var createCoursesSql = `
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var (
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createCoursesSql = `
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CREATE TABLE courses (
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id serial PRIMARY KEY,
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name text
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);`
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dropCoursesSql = `DROP TABLE courses;`
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var createUsersSql = `
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createUsersSql = `
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CREATE TABLE users (
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id serial PRIMARY KEY,
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email text UNIQUE NOT NULL
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);`
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dropUsersSql = `DROP TABLE users;`
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)
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@ -0,0 +1,2 @@
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DROP TABLE widgets;
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