add ability to specify limits and the target version to migrate to

main.go

@@ -109,6 +109,7 @@ func NewApp() *cli.App {
  },
  },
  Action: action(func(db *dbmate.DB, c *cli.Context) error {
+ db.TargetVersion = c.Args().First()
  db.Verbose = c.Bool("verbose")
  return db.CreateAndMigrate()
  }),
@@ -129,7 +130,7 @@ func NewApp() *cli.App {
  },
  {
  Name: "migrate",
- Usage: "Migrate to the latest version",
+ Usage: "Migrate to the specified or latest version",
  Flags: []cli.Flag{
  &cli.BoolFlag{
  Name: "verbose",
@@ -139,6 +140,7 @@ func NewApp() *cli.App {
  },
  },
  Action: action(func(db *dbmate.DB, c *cli.Context) error {
+ db.TargetVersion = c.Args().First()
  db.Verbose = c.Bool("verbose")
  return db.Migrate()
  }),
@@ -154,8 +156,16 @@ func NewApp() *cli.App {
  EnvVars: []string{"DBMATE_VERBOSE"},
  Usage: "print the result of each statement execution",
  },
+ &cli.IntFlag{
+ Name: "limit",
+ Aliases: []string{"l"},
+ Usage: "Limits the amount of rollbacks (defaults to 1 if no target version is specified)",
+ Value: -1,
+ },
  },
  Action: action(func(db *dbmate.DB, c *cli.Context) error {
+ db.TargetVersion = c.Args().First()
+ db.Limit = c.Int("limit")
  db.Verbose = c.Bool("verbose")
  return db.Rollback()
  }),

pkg/dbmate/db.go

@@ -41,6 +41,8 @@ type DB struct {
  WaitBefore bool
  WaitInterval time.Duration
  WaitTimeout time.Duration
+ Limit int
+ TargetVersion string
  Log io.Writer
 }
 
@@ -64,6 +66,8 @@ func New(databaseURL *url.URL) *DB {
  WaitBefore: false,
  WaitInterval: DefaultWaitInterval,
  WaitTimeout: DefaultWaitTimeout,
+ Limit: -1,
+ TargetVersion: "",
  Log: os.Stdout,
  }
 }
@@ -336,14 +340,14 @@ func (db *DB) migrate(drv Driver) error {
  }
  defer dbutil.MustClose(sqlDB)
 
- applied, err := drv.SelectMigrations(sqlDB, -1)
+ applied, err := drv.SelectMigrations(sqlDB, db.Limit)
  if err != nil {
  return err
  }
 
  for _, filename := range files {
  ver := migrationVersion(filename)
- if ok := applied[ver]; ok {
+ if ok := applied[ver]; ok && ver != db.TargetVersion {
  // migration already applied
  continue
  }
@@ -379,6 +383,11 @@ func (db *DB) migrate(drv Driver) error {
  if err != nil {
  return err
  }
+
+ if ver == db.TargetVersion {
+ fmt.Fprintf(db.Log, "Reached target version %s\n", ver)
+ break
+ }
  }
 
  // automatically update schema file, silence errors
@@ -469,55 +478,83 @@ func (db *DB) Rollback() error {
  }
  defer dbutil.MustClose(sqlDB)
 
- applied, err := drv.SelectMigrations(sqlDB, 1)
+ limit := db.Limit
+ // default limit is -1, if we don't specify a version it should only rollback one version, not all
+ if limit <= 0 && db.TargetVersion == "" {
+ limit = 1
+ }
+
+ applied, err := drv.SelectMigrations(sqlDB, limit)
  if err != nil {
  return err
  }
 
- // grab most recent applied migration (applied has len=1)
- latest := ""
- for ver := range applied {
- latest = ver
- }
- if latest == "" {
- return fmt.Errorf("can't rollback: no migrations have been applied")
+ if len(applied) == 0 {
+ return fmt.Errorf("can't rollback, no migrations found")
  }
 
- filename, err := findMigrationFile(db.MigrationsDir, latest)
- if err != nil {
- return err
+ var versions []string
+ for v := range applied {
+ versions = append(versions, v)
  }
 
- fmt.Fprintf(db.Log, "Rolling back: %s\n", filename)
+ // new → old
+ sort.Sort(sort.Reverse(sort.StringSlice(versions)))
 
- _, down, err := parseMigration(filepath.Join(db.MigrationsDir, filename))
- if err != nil {
- return err
+ if db.TargetVersion != "" {
+ cache := map[string]bool{}
+ found := false
+
+ // latest version comes first, so take every version until the version matches
+ for _, ver := range versions {
+ if ver == db.TargetVersion {
+ found = true
+ break
+ }
+ cache[ver] = true
+ }
+ if !found {
+ return fmt.Errorf("target version not found")
+ }
+ applied = cache
  }
 
- execMigration := func(tx dbutil.Transaction) error {
- // rollback migration
- result, err := tx.Exec(down.Contents)
+ for version := range applied {
+ filename, err := findMigrationFile(db.MigrationsDir, version)
  if err != nil {
  return err
- } else if db.Verbose {
- db.printVerbose(result)
  }
 
- // remove migration record
- return drv.DeleteMigration(tx, latest)
- }
+ fmt.Fprintf(db.Log, "Rolling back: %s\n", filename)
+ _, down, err := parseMigration(filepath.Join(db.MigrationsDir, filename))
+ if err != nil {
+ return err
+ }
 
- if down.Options.Transaction() {
- // begin transaction
- err = doTransaction(sqlDB, execMigration)
- } else {
- // run outside of transaction
- err = execMigration(sqlDB)
- }
+ execMigration := func(tx dbutil.Transaction) error {
+ // rollback migration
+ result, err := tx.Exec(down.Contents)
+ if err != nil {
+ return err
+ } else if db.Verbose {
+ db.printVerbose(result)
+ }
 
- if err != nil {
- return err
+ // remove migration record
+ return drv.DeleteMigration(tx, version)
+ }
+
+ if down.Options.Transaction() {
+ // begin transaction
+ err = doTransaction(sqlDB, execMigration)
+ } else {
+ // run outside of transaction
+ err = execMigration(sqlDB)
+ }
+
+ if err != nil {
+ return err
+ }
  }
 
  // automatically update schema file, silence errors
@@ -582,7 +619,7 @@ func (db *DB) CheckMigrationsStatus(drv Driver) ([]StatusResult, error) {
  }
  defer dbutil.MustClose(sqlDB)
 
- applied, err := drv.SelectMigrations(sqlDB, -1)
+ applied, err := drv.SelectMigrations(sqlDB, db.Limit)
  if err != nil {
  return nil, err
  }