feat(backend/db): add transaction wrapper

backend/db/db.go

@@ -3,12 +3,14 @@ package db
 import (
 	"context"
 	"fmt"
+	"net/http"
 	"time"
 
+	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
 )
 
-var ConnPool *pgxpool.Pool
+var connPool *pgxpool.Pool
 
 func InitDB(connString string) error {
 	poolConfig, err := pgxpool.ParseConfig(connString)
@@ -21,9 +23,27 @@ func InitDB(connString string) error {
 	poolConfig.MaxConnLifetime = time.Hour
 	poolConfig.HealthCheckPeriod = 30 * time.Second
 
-	ConnPool, err = pgxpool.NewWithConfig(context.Background(), poolConfig)
+	connPool, err = pgxpool.NewWithConfig(context.Background(), poolConfig)
 	if err != nil {
 		return fmt.Errorf("error while initializing DB connections pool: %w", err)
 	}
 	return nil
 }
+
+func transaction(ctx context.Context, handler func(pgx.Tx) (statusCode int, err error)) (statusCode int, err error) {
+	tx, err := connPool.Begin(ctx)
+	if err != nil {
+		statusCode = http.StatusInternalServerError
+		return
+	}
+	statusCode, err = handler(tx)
+	if err != nil {
+		tx.Rollback(ctx)
+		return
+	}
+	err = tx.Commit(ctx)
+	if err != nil {
+		statusCode = http.StatusInternalServerError
+	}
+	return
+}