go.mod

@@ -1,3 +0,0 @@
-module git.fuyu.moe/Fuyu/migrate/v2
-
-go 1.16

migrate.go

@@ -5,7 +5,6 @@ import (
 	"database/sql"
 	"errors"
 	"fmt"
-	"io/fs"
 	"strconv"
 )
 
@@ -13,6 +12,7 @@ import (
 type Options struct {
 	TableName   string // Name used for version info table; defaults to DefaultTableName if not set
 	Schema      string // Schema used for version info table; In PostgreSQL the current schema is changed to the one specified here
+	AssetPrefix string
 }
 
 // DefaultTableName is the name used when no TableName is specified in Options
@@ -26,15 +26,16 @@ const fileFormat = `%04d.sql`
 // AssetFunc is a function that returns the data for the given name
 type AssetFunc func(string) ([]byte, error)
 
-// Migrate executes all migrations
+// Migrate executes migrations to get to the desired version
-// Filenames need to have incrementing numbers
 // Downgrading is not supported as it could result in data loss
-func Migrate(db *sql.DB, o Options, assets fs.FS) error {
+func Migrate(db *sql.DB, version int, o Options, asset AssetFunc) error {
-	entries, err := fs.ReadDir(assets, `.`)
+	dbType := getDbType(db)
-	if err != nil {
+	if o.TableName == `` {
-		panic(`failed to read list of files`)
+		o.TableName = DefaultTableName
 	}
-	version := len(entries)
+
+	var err error
+	searchPath := `public`
 
 	tx, err := db.Begin()
 	if err != nil {
@@ -42,12 +43,6 @@ func Migrate(db *sql.DB, o Options, assets fs.FS) error {
 	}
 	defer tx.Rollback()
 
-	dbType := getDbType(db)
-	searchPath := `public`
-	if o.TableName == `` {
-		o.TableName = DefaultTableName
-	}
-
 	if o.Schema != `` {
 		err = createSchemaIfNotExists(tx, o.Schema)
 		if err != nil {
@@ -78,10 +73,10 @@ func Migrate(db *sql.DB, o Options, assets fs.FS) error {
 	}
 
 	for i := v + 1; i <= version; i++ {
-		fileName := fmt.Sprintf(fileFormat, i)
+		fileName := fmt.Sprintf(o.AssetPrefix+fileFormat, i)
 		errorf := func(e error) error { return fmt.Errorf(`migration "%s" failed: %w`, fileName, e) }
 
-		script, err := fs.ReadFile(assets, fileName)
+		script, err := asset(fileName)
 		if err != nil {
 			return errorf(ErrUpdatesMissing)
 		}