2 files changed, 46 insertions(+), 8 deletions(-)

M db.go
M schema.sql

@@ 13,6 13,10 @@ import (
 //go:embed schema.sql
 var schema string
 
+var migrations = []string{
+	"", // migration #0 is reserved for schema initialization
+}
+
 var errNoDBRows = sql.ErrNoRows
 
 type DB struct {


@@ 35,15 39,13 @@ func openDB(filename string) (*DB, error) {
 }
 
 func (db *DB) init(ctx context.Context) error {
-	var n int
-	if err := db.db.QueryRowContext(ctx, "SELECT COUNT(*) FROM sqlite_schema").Scan(&n); err != nil {
+	version, err := db.upgrade(ctx)
+	if err != nil {
 		return err
-	} else if n != 0 {
-		return nil
 	}
 
-	if _, err := db.db.ExecContext(ctx, schema); err != nil {
-		return err
+	if version > 0 {
+		return nil
 	}
 
 	// TODO: drop this


@@ 54,6 56,44 @@ func (db *DB) init(ctx context.Context) error {
 	return db.StoreUser(ctx, &defaultUser)
 }
 
+func (db *DB) upgrade(ctx context.Context) (version int, err error) {
+	if err := db.db.QueryRow("PRAGMA user_version").Scan(&version); err != nil {
+		return 0, fmt.Errorf("failed to query schema version: %v", err)
+	}
+
+	if version == len(migrations) {
+		return version, nil
+	} else if version > len(migrations) {
+		return version, fmt.Errorf("sinwon (version %d) older than schema (version %d)", len(migrations), version)
+	}
+
+	tx, err := db.db.Begin()
+	if err != nil {
+		return version, err
+	}
+	defer tx.Rollback()
+
+	if version == 0 {
+		if _, err := tx.Exec(schema); err != nil {
+			return version, fmt.Errorf("failed to initialize schema: %v", err)
+		}
+	} else {
+		for i := version; i < len(migrations); i++ {
+			if _, err := tx.Exec(migrations[i]); err != nil {
+				return version, fmt.Errorf("failed to execute migration #%v: %v", i, err)
+			}
+		}
+	}
+
+	// For some reason prepared statements don't work here
+	_, err = tx.Exec(fmt.Sprintf("PRAGMA user_version = %d", len(migrations)))
+	if err != nil {
+		return version, fmt.Errorf("failed to bump schema version: %v", err)
+	}
+
+	return version, tx.Commit()
+}
+
 func (db *DB) Close() error {
 	return db.db.Close()
 }

@@ 1,5 1,3 @@
-PRAGMA user_version = 1;
-
 CREATE TABLE User (
 	id INTEGER PRIMARY KEY,
 	username TEXT NOT NULL UNIQUE,