Fix go migration up

down.go

@@ -1,25 +1,21 @@
 package goose
 
-import (
-	"database/sql"
-	"fmt"
-)
+import "database/sql"
 
 func Down(db *sql.DB, dir string) error {
 	current, err := GetDBVersion(db)
 	if err != nil {
 		return err
 	}
 
-	previous, err := GetPreviousDBVersion(dir, current)
+	migrations, err := CollectMigrations(dir, minVersion, maxVersion)
 	if err != nil {
-		if err != nil {
-			if err == ErrNoPreviousVersion {
-				fmt.Printf("goose: no migrations to run. current version: %d\n", current)
-			}
-			return err
-		}
+		return err
+	}
+	migrations.Sort(false) // descending, Next will be Previous
 
+	previous, err := migrations.Next(current)
+	if err != nil {
 		return err
 	}
 

goose.go

@@ -18,10 +18,9 @@ func checkVersionDuplicates(dir string) error {
 		return err
 	}
 
-	// Try sorting all migrations, so we get panic on any duplicates.
-	ms := migrationSorter(migrations)
-	ms.Sort(true)
-	ms.Sort(false)
+	// try both directions
+	migrations.Sort(false)
+	migrations.Sort(true)
 	return nil
 }
 

migrate.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 	"fmt"
 	"log"
-	"os"
 	"path/filepath"
 	"runtime"
 	"sort"
@@ -18,7 +17,10 @@ import (
 var (
 	ErrNoPreviousVersion = errors.New("no previous version found")
 	ErrNoNextVersion     = errors.New("no next version found")
-	goMigrations         []*Migration
+
+	MaxVersion = 9223372036854775807 // max(int64)
+
+	goMigrations []*Migration
 )
 
 type MigrationRecord struct {
@@ -36,18 +38,59 @@ type Migration struct {
 	Down     func(*sql.Tx) error // Down go migration function
 }
 
-type migrationSorter []*Migration
+type Migrations []*Migration
 
 // helpers so we can use pkg sort
-func (ms migrationSorter) Len() int      { return len(ms) }
-func (ms migrationSorter) Swap(i, j int) { ms[i], ms[j] = ms[j], ms[i] }
-func (ms migrationSorter) Less(i, j int) bool {
+func (ms Migrations) Len() int      { return len(ms) }
+func (ms Migrations) Swap(i, j int) { ms[i], ms[j] = ms[j], ms[i] }
+func (ms Migrations) Less(i, j int) bool {
 	if ms[i].Version == ms[j].Version {
 		log.Fatalf("goose: duplicate version %v detected:\n%v\n%v", ms[i].Version, ms[i].Source, ms[j].Source)
 	}
 	return ms[i].Version < ms[j].Version
 }
 
+func (ms Migrations) Sort(up bool) {
+
+	// sort ascending or descending by version
+	if up {
+		sort.Sort(ms)
+	} else {
+		sort.Sort(sort.Reverse(ms))
+	}
+
+	// now that we're sorted in the appropriate direction,
+	// populate next and previous for each migration
+	for i, m := range ms {
+		prev := int64(-1)
+		if i > 0 {
+			prev = ms[i-1].Version
+			ms[i-1].Next = m.Version
+		}
+		ms[i].Previous = prev
+	}
+}
+
+func (ms Migrations) Last() (int64, error) {
+	if len(ms) == 0 {
+		return -1, ErrNoNextVersion
+	}
+
+	return ms[len(ms)-1].Version, nil
+}
+
+func (ms Migrations) Next(current int64) (int64, error) {
+	exceptLast := ms[:len(ms)-1]
+
+	for i, migration := range exceptLast {
+		if migration.Version == current {
+			return ms[i+1].Version, nil
+		}
+	}
+
+	return -1, ErrNoNextVersion
+}
+
 func AddMigration(up func(*sql.Tx) error, down func(*sql.Tx) error) {
 	_, filename, _, _ := runtime.Caller(1)
 	v, _ := NumericComponent(filename)
@@ -77,7 +120,7 @@ func RunMigrations(db *sql.DB, dir string, target int64) (err error) {
 		return nil
 	}
 
-	ms := migrationSorter(migrations)
+	ms := Migrations(migrations)
 	direction := current < target
 	ms.Sort(direction)
 
@@ -122,7 +165,7 @@ func RunMigrations(db *sql.DB, dir string, target int64) (err error) {
 
 // collect all the valid looking migration scripts in the
 // migrations folder and go func registry, and key them by version
-func CollectMigrations(dirpath string, current, target int64) (m []*Migration, err error) {
+func CollectMigrations(dirpath string, current, target int64) (m Migrations, err error) {
 
 	// extract the numeric component of each migration,
 	// filter out any uninteresting files,
@@ -169,27 +212,6 @@ func versionFilter(v, current, target int64) bool {
 	return false
 }
 
-func (ms migrationSorter) Sort(direction bool) {
-
-	// sort ascending or descending by version
-	if direction {
-		sort.Sort(ms)
-	} else {
-		sort.Sort(sort.Reverse(ms))
-	}
-
-	// now that we're sorted in the appropriate direction,
-	// populate next and previous for each migration
-	for i, m := range ms {
-		prev := int64(-1)
-		if i > 0 {
-			prev = ms[i-1].Version
-			ms[i-1].Next = m.Version
-		}
-		ms[i].Previous = prev
-	}
-}
-
 // look for migration scripts with names in the form:
 //  XXX_descriptivename.ext
 // where XXX specifies the version number
@@ -298,95 +320,6 @@ func GetDBVersion(db *sql.DB) (int64, error) {
 	return version, nil
 }
 
-func GetPreviousDBVersion(dirpath string, version int64) (previous int64, err error) {
-
-	previous = -1
-	sawGivenVersion := false
-
-	filepath.Walk(dirpath, func(name string, info os.FileInfo, walkerr error) error {
-
-		if !info.IsDir() {
-			if v, e := NumericComponent(name); e == nil {
-				if v > previous && v < version {
-					previous = v
-				}
-				if v == version {
-					sawGivenVersion = true
-				}
-			}
-		}
-
-		return nil
-	})
-
-	if previous == -1 {
-		if sawGivenVersion {
-			// the given version is (likely) valid but we didn't find
-			// anything before it.
-			// 'previous' must reflect that no migrations have been applied.
-			previous = 0
-		} else {
-			err = ErrNoPreviousVersion
-		}
-	}
-
-	return
-}
-
-func GetNextDBVersion(dirpath string, version int64) (next int64, err error) {
-
-	next = 9223372036854775807 // max(int64)
-
-	filepath.Walk(dirpath, func(name string, info os.FileInfo, walkerr error) error {
-
-		if !info.IsDir() {
-			if v, e := NumericComponent(name); e == nil {
-				if v < next && v > version {
-					next = v
-				}
-			}
-		}
-
-		return nil
-	})
-
-	if next == 9223372036854775807 {
-		next = version
-		err = ErrNoNextVersion
-	}
-
-	return
-}
-
-// helper to identify the most recent possible version
-// within a folder of migration scripts
-func GetMostRecentDBVersion(dirpath string) (version int64, err error) {
-
-	version = -1
-
-	filepath.Walk(dirpath, func(name string, info os.FileInfo, walkerr error) error {
-		if walkerr != nil {
-			return walkerr
-		}
-
-		if !info.IsDir() {
-			if v, e := NumericComponent(name); e == nil {
-				if v > version {
-					version = v
-				}
-			}
-		}
-
-		return nil
-	})
-
-	if version == -1 {
-		err = errors.New("no valid version found")
-	}
-
-	return
-}
-
 func CreateMigration(name, migrationType, dir string, t time.Time) (path string, err error) {
 
 	if migrationType != "go" && migrationType != "sql" {

migrate_test.go

@@ -10,7 +10,7 @@ func newMigration(v int64, src string) *Migration {
 
 func TestMigrationMapSortUp(t *testing.T) {
 
-	ms := migrationSorter{}
+	ms := Migrations{}
 
 	// insert in any order
 	ms = append(ms, newMigration(20120000, "test"))
@@ -27,7 +27,7 @@ func TestMigrationMapSortUp(t *testing.T) {
 
 func TestMigrationMapSortDown(t *testing.T) {
 
-	ms := migrationSorter{}
+	ms := Migrations{}
 
 	// insert in any order
 	ms = append(ms, newMigration(20120000, "test"))
@@ -42,7 +42,7 @@ func TestMigrationMapSortDown(t *testing.T) {
 	validateMigrationSort(t, ms, sorted)
 }
 
-func validateMigrationSort(t *testing.T, ms migrationSorter, sorted []int64) {
+func validateMigrationSort(t *testing.T, ms Migrations, sorted []int64) {
 
 	for i, m := range ms {
 		if sorted[i] != m.Version {

redo.go

@@ -10,7 +10,13 @@ func Redo(db *sql.DB, dir string) error {
 		return err
 	}
 
-	previous, err := GetPreviousDBVersion(dir, current)
+	migrations, err := CollectMigrations(dir, minVersion, maxVersion)
+	if err != nil {
+		return err
+	}
+	migrations.Sort(false) // descending, Next will be Previous
+
+	previous, err := migrations.Next(current)
 	if err != nil {
 		return err
 	}

status.go

@@ -14,9 +14,7 @@ func Status(db *sql.DB, dir string) error {
 	if err != nil {
 		return err
 	}
-
-	ms := migrationSorter(migrations)
-	ms.Sort(true)
+	migrations.Sort(true)
 
 	// must ensure that the version table exists if we're running on a pristine DB
 	if _, err := EnsureDBVersion(db); err != nil {
@@ -26,8 +24,8 @@ func Status(db *sql.DB, dir string) error {
 	fmt.Println("goose: status")
 	fmt.Println("    Applied At                  Migration")
 	fmt.Println("    =======================================")
-	for _, m := range ms {
-		printMigrationStatus(db, m.Version, filepath.Base(m.Source))
+	for _, migration := range migrations {
+		printMigrationStatus(db, migration.Version, filepath.Base(migration.Source))
 	}
 
 	return nil

up.go

@@ -6,7 +6,13 @@ import (
 )
 
 func Up(db *sql.DB, dir string) error {
-	target, err := GetMostRecentDBVersion(dir)
+	migrations, err := CollectMigrations(dir, minVersion, maxVersion)
+	if err != nil {
+		return err
+	}
+	migrations.Sort(true)
+
+	target, err := migrations.Last()
 	if err != nil {
 		return err
 	}
@@ -18,12 +24,18 @@ func Up(db *sql.DB, dir string) error {
 }
 
 func UpByOne(db *sql.DB, dir string) error {
+	migrations, err := CollectMigrations(dir, minVersion, maxVersion)
+	if err != nil {
+		return err
+	}
+	migrations.Sort(true)
+
 	current, err := GetDBVersion(db)
 	if err != nil {
 		return err
 	}
 
-	next, err := GetNextDBVersion(dir, current)
+	next, err := migrations.Next(current)
 	if err != nil {
 		if err == ErrNoNextVersion {
 			fmt.Printf("goose: no migrations to run. current version: %d\n", current)