Add auto migration

main.go

@@ -18,6 +18,13 @@ func main() {
 		os.Exit(1)
 	}
 
+	migrationsDir := "./migrations" 
+	if err := utils.ApplyMigrations(db, migrationsDir); err != nil {
+		log.Fatalf("failed to apply migrations: %v", err)
+		os.Exit(1)
+	}
+
+
 	port := flag.String("port", os.Getenv("PORT"), "server address to listen on")
 	flag.Parse()
 

migrations/20230912194711_init.down.sql

@@ -1 +1,9 @@
+BEGIN;
+
+-- Check and drop the tiny_url table first if it exists.
+DROP TABLE IF EXISTS tiny_url;
+
+-- Now it is safe to drop the users table.
 DROP TABLE IF EXISTS users;
+
+COMMIT;

utils/migration.go

@@ -0,0 +1,52 @@
+package utils
+
+import (
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/uptrace/bun"
+)
+
+func ApplyMigrations(db *bun.DB, migrationsDir string) error {
+	log.Println("Starting migration process...")
+	files, err := os.ReadDir(migrationsDir)
+	if err != nil {
+		log.Printf("Error reading migration directory: %v", err)
+		return err
+	}
+
+	for _, file := range files {
+		if !file.IsDir() && strings.HasSuffix(file.Name(), ".sql") {
+			log.Printf("Applying migration from file: %s", file.Name())
+			content, err := os.ReadFile(filepath.Join(migrationsDir, file.Name()))
+			if err != nil {
+				log.Printf("Error reading file %s: %v", file.Name(), err)
+				return err
+			}
+
+			tx, err := db.Begin()
+			if err != nil {
+				log.Printf("Error starting transaction: %v", err)
+				return err
+			}
+
+			_, err = tx.Exec(string(content))
+			if err != nil {
+				tx.Rollback()
+				log.Printf("Error executing migration %s: %v", file.Name(), err)
+				return err
+			}
+
+			err = tx.Commit()
+			if err != nil {
+				log.Printf("Error committing transaction for %s: %v", file.Name(), err)
+				return err
+			}
+			log.Printf("Successfully applied migration: %s", file.Name())
+		}
+	}
+	log.Println("Migration process completed successfully.")
+	return nil
+}