How to use cc.blynk.server.db.model

private void insertPurchase(String email, int reward, double price, String transactionId) {
  if (transactionId.equals("AdColonyAward") || transactionId.equals("homeScreen")) {
    return;
  }
  blockingIOProcessor.executeDB(
    () -> dbManager.insertPurchase(new Purchase(email, reward, price, transactionId))
  );
}

public Redeem selectRedeemByToken(String token) throws Exception {
  log.info("Redeem select for {}", token);
  try (Connection connection = ds.getConnection();
     PreparedStatement statement = connection.prepareStatement(selectRedeemToken)) {
    statement.setString(1, token);
    try (ResultSet rs = statement.executeQuery()) {
      connection.commit();
      if (rs.next()) {
        return new Redeem(rs.getString("token"), rs.getString("company"),
            rs.getBoolean("isRedeemed"), rs.getString("email"),
            rs.getInt("reward"), rs.getInt("version"),
            rs.getDate("ts")
        );
      }
    }
  }
  return null;
}

public FlashedToken selectFlashedToken(String token) {
  log.info("Select flashed token {}.", token);
  try (Connection connection = ds.getConnection();
     PreparedStatement statement = connection.prepareStatement(selectToken)) {
    statement.setString(1, token);
    try (ResultSet rs = statement.executeQuery()) {
      connection.commit();
      if (rs.next()) {
        return new FlashedToken(rs.getString("token"), rs.getString("app_name"),
            rs.getString("email"), rs.getInt("project_id"), rs.getInt("device_id"),
            rs.getBoolean("is_activated"), rs.getDate("ts")
        );
      }
    }
  } catch (Exception e) {
    log.error("Error getting flashed token.", e);
  }
  return null;
}

  private QrHolder[] makeQRs(User user, String appId, DashBoard dash) throws Exception {
    int tokensCount = dash.devices.length;
    QrHolder[] qrHolders = new QrHolder[tokensCount];
    FlashedToken[] flashedTokens = new FlashedToken[tokensCount];

    int i = 0;
    for (Device device : dash.devices) {
      String newToken = TokenGeneratorUtil.generateNewToken();
      qrHolders[i] = new QrHolder(dash.id, device.id, device.name, newToken,
          QRCode.from(newToken).to(ImageType.JPG).stream().toByteArray());
      flashedTokens[i++] = new FlashedToken(user.email, newToken, appId, dash.id, device.id);
    }

    if (!dbManager.insertFlashedTokens(flashedTokens)) {
      throw new Exception("App Publishing Preview requires enabled DB.");
    }

    return qrHolders;
  }
}

QrHolder qrHolder = new QrHolder(dash.id, -1, null, newToken,
      QRCode.from(newToken).to(ImageType.JPG).stream().toByteArray());
FlashedToken flashedToken = new FlashedToken(to, newToken, publishAppId, dash.id, -1);