fix backup empty tables

database/backup.go

@@ -40,6 +40,7 @@ func GetDb(exclude string) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
+	defer os.Remove(dbPath)
 
 	err = backupDb.AutoMigrate(
 		&model.Setting{},
@@ -69,29 +70,50 @@ func GetDb(exclude string) ([]byte, error) {
 	// Perform scans and handle errors
 	if err := db.Model(&model.Setting{}).Scan(&settings).Error; err != nil {
 		return nil, err
+	} else if len(settings) > 0 {
+		if err := backupDb.Save(settings).Error; err != nil {
+			return nil, err
+		}
 	}
 	if err := db.Model(&model.Tls{}).Scan(&tls).Error; err != nil {
 		return nil, err
+	} else if len(tls) > 0 {
+		if err := backupDb.Save(tls).Error; err != nil {
+			return nil, err
+		}
 	}
 	if err := db.Model(&model.Inbound{}).Scan(&inbound).Error; err != nil {
 		return nil, err
+	} else if len(inbound) > 0 {
+		if err := backupDb.Save(inbound).Error; err != nil {
+			return nil, err
+		}
 	}
 	if err := db.Model(&model.Outbound{}).Scan(&outbound).Error; err != nil {
 		return nil, err
+	} else if len(outbound) > 0 {
+		if err := backupDb.Save(outbound).Error; err != nil {
+			return nil, err
+		}
 	}
 	if err := db.Model(&model.Endpoint{}).Scan(&endpoint).Error; err != nil {
 		return nil, err
+	} else if len(endpoint) > 0 {
+		if err := backupDb.Save(endpoint).Error; err != nil {
+			return nil, err
+		}
 	}
 	if err := db.Model(&model.User{}).Scan(&users).Error; err != nil {
 		return nil, err
+	} else if len(users) > 0 {
+		if err := backupDb.Save(users).Error; err != nil {
+			return nil, err
+		}
 	}
 	if err := db.Model(&model.Client{}).Scan(&clients).Error; err != nil {
 		return nil, err
-	}
-
-	// Save each model
-	for _, mdl := range []interface{}{settings, tls, inbound, outbound, endpoint, users, clients} {
-		if err := backupDb.Save(mdl).Error; err != nil {
+	} else if len(clients) > 0 {
+		if err := backupDb.Save(clients).Error; err != nil {
 			return nil, err
 		}
 	}
@@ -132,7 +154,6 @@ func GetDb(exclude string) ([]byte, error) {
 		return nil, err
 	}
 	defer file.Close()
-	defer os.Remove(dbPath)
 
 	// Read the file contents
 	fileContents, err := io.ReadAll(file)