up: make use of filepath.Walk to simplify traversing migration files

migrate.go

@@ -190,12 +190,19 @@ func (m *MigrationMap) Sort(direction bool) {
 //  XXX_descriptivename.ext
 // where XXX specifies the version number
 // and ext specifies the type of migration
-func numericComponent(path string) (int, error) {
-	idx := strings.Index(path, "_")
+func numericComponent(name string) (int, error) {
+
+	base := path.Base(name)
+
+	if ext := path.Ext(base); ext != ".go" && ext != ".sql" {
+		return 0, errors.New("not a recognized migration file type")
+	}
+
+	idx := strings.Index(base, "_")
 	if idx < 0 {
 		return 0, errors.New("no separator found")
 	}
-	return strconv.Atoi(path[:idx])
+	return strconv.Atoi(base[:idx])
 }
 
 // retrieve the current version for this DB.

up.go

@@ -4,6 +4,7 @@ import (
 	"log"
 	"os"
 	"path"
+	"path/filepath"
 )
 
 var upCmd = &Command{
@@ -32,33 +33,18 @@ func upRun(cmd *Command, args ...string) {
 // within a folder of migration scripts
 func mostRecentVersionAvailable(dirpath string) int {
 
-	dir, err := os.Open(dirpath)
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	names, err := dir.Readdirnames(0)
-	if err != nil {
-		log.Fatal(err)
-	}
-
 	mostRecent := -1
 
-	for _, name := range names {
+	filepath.Walk(dirpath, func(name string, info os.FileInfo, err error) error {
 
-		if ext := path.Ext(name); ext != ".go" && ext != ".sql" {
-			continue
+		if v, e := numericComponent(name); e == nil {
+			if v > mostRecent {
+				mostRecent = v
+			}
 		}
 
-		v, e := numericComponent(name)
-		if e != nil {
-			continue
-		}
-
-		if v > mostRecent {
-			mostRecent = v
-		}
-	}
+		return nil
+	})
 
 	return mostRecent
 }