refactor: 封装 Redis key 生成函数

backend/internal/repository/redeem_cache.go

@@ -15,6 +15,16 @@ const (
 	redeemRateLimitDuration  = 24 * time.Hour
 )
 
+// redeemRateLimitKey generates the Redis key for redeem attempt rate limiting.
+func redeemRateLimitKey(userID int64) string {
+	return fmt.Sprintf("%s%d", redeemRateLimitKeyPrefix, userID)
+}
+
+// redeemLockKey generates the Redis key for redeem code locking.
+func redeemLockKey(code string) string {
+	return redeemLockKeyPrefix + code
+}
+
 type redeemCache struct {
 	rdb *redis.Client
 }
@@ -24,12 +34,16 @@ func NewRedeemCache(rdb *redis.Client) service.RedeemCache {
 }
 
 func (c *redeemCache) GetRedeemAttemptCount(ctx context.Context, userID int64) (int, error) {
-	key := fmt.Sprintf("%s%d", redeemRateLimitKeyPrefix, userID)
-	return c.rdb.Get(ctx, key).Int()
+	key := redeemRateLimitKey(userID)
+	count, err := c.rdb.Get(ctx, key).Int()
+	if err == redis.Nil {
+		return 0, nil
+	}
+	return count, err
 }
 
 func (c *redeemCache) IncrementRedeemAttemptCount(ctx context.Context, userID int64) error {
-	key := fmt.Sprintf("%s%d", redeemRateLimitKeyPrefix, userID)
+	key := redeemRateLimitKey(userID)
 	pipe := c.rdb.Pipeline()
 	pipe.Incr(ctx, key)
 	pipe.Expire(ctx, key, redeemRateLimitDuration)
@@ -38,11 +52,11 @@ func (c *redeemCache) IncrementRedeemAttemptCount(ctx context.Context, userID in
 }
 
 func (c *redeemCache) AcquireRedeemLock(ctx context.Context, code string, ttl time.Duration) (bool, error) {
-	key := redeemLockKeyPrefix + code
+	key := redeemLockKey(code)
 	return c.rdb.SetNX(ctx, key, 1, ttl).Result()
 }
 
 func (c *redeemCache) ReleaseRedeemLock(ctx context.Context, code string) error {
-	key := redeemLockKeyPrefix + code
+	key := redeemLockKey(code)
 	return c.rdb.Del(ctx, key).Err()
 }