Saving & retrieving sessions in Redis

SessionStore.ts

  // Save a session for a user and their online status
  saveSession(id: string, { username, connected }: { [key: string]: string }) {
    this.redisClient
      .multi()
      .hmset(`session:${id}`, "username", username, "connected", connected)
      .expire(`session:${id}`, SESSION_TTL)
      .exec();
  }

  // Retrieve a user's session
  findSession(id: String): Promise<{username: string, online: boolean}[]> {
    return new Promise((resolve, reject) =>
      this.redisClient.hmget(
        `session:${id}`,
        "username",
        "connected",
        (err: Error | null, valueArray: string[] | null) => {
          if (valueArray) {
            return resolve(mapSession(valueArray));
          }
          if (err) {
            reject(err);
          }
          reject();
        }
      )
    );
  }