express#RequestHandler TypeScript Examples

export function requireSameOrigin(): RequestHandler {
  return (req, res, next) => {
    const reqOrigin = req.headers['origin'];

    if (reqOrigin !== origin) {
      res.status(403).json({ err: 'Request must be same origin' });
      return;
    }

    next();
  };
}

export function mapClass(cls: ClassConstructor<object>): RequestHandler {
    return async (req: Request, res: Response, next: NextFunction) => {
        // Map to class
        let obj: object = plainToInstance(cls, req.body);

        // Validate class
        let errors = await validate(obj, {
            skipMissingProperties: true,
            whitelist: true,
            forbidNonWhitelisted: false,
            forbidUnknownValues: true,
        });
        if (errors.length > 0) {
            res.status(400).send({ error: true, errors: formatValidationErrors(errors) });
            return;
        }

        // Set validated class to locals
        res.locals.input = obj;
        next();
    };
}

/**
 * This utility checks that the server's configuration matches
 * the criteria.
 */
function validateConfiguration(
  options: ValidationOptions<MonkeyTypes.Configuration>
): RequestHandler {
  const {
    criteria,
    invalidMessage = "This service is currently unavailable.",
  } = options;

  return (req: MonkeyTypes.Request, _res: Response, next: NextFunction) => {
    const configuration = req.ctx.configuration;

    const validated = criteria(configuration);
    if (!validated) {
      throw new MonkeyError(503, invalidMessage);
    }

    next();
  };
}

export function maybeRequireLogin(): RequestHandler {
  return (req, res, next) => {
    if (!requirePlayerLogin || req.session!.user) {
      next();
      return;
    }

    const error = 'Login required';
    res.status(403).send(error);
  };
}

export function checkAuth(token: string): RequestHandler {
    return (req, res, next) => {
        if (req.headers.authorization !== token) {
            res.sendStatus(401);
            return;
        }
        next();
    };
}

/**
 * A function used to wrap asynchronous Express middlewares.
 * It catches async errors so Express can pass them to an error handling middleware.
 *
 * @param handler - An Express middleware function.
 *
 * @returns An Express middleware capable of catching asynchronous errors.
 */
export function wrapAsync(handler: RequestHandler): RequestHandler {
  return async (
    req: Request,
    res: Response,
    next: NextFunction,
  ): Promise<void> => Promise.resolve(handler(req, res, next)).catch(next)
}

createNotFoundHandler =
  (errorHandler: AnyResultHandler, logger: Logger): RequestHandler =>
  (request, response) => {
    const error = createHttpError(
      404,
      `Can not ${request.method} ${request.path}`
    );
    try {
      errorHandler.handler({
        request,
        response,
        logger,
        error,
        input: null,
        output: null,
      });
    } catch (e) {
      if (e instanceof Error) {
        lastResortHandler({
          response,
          logger,
          error: new ResultHandlerError(e.message, error),
        });
      }
    }
  }

/**
 * Runs an async function and catches the errors thrown in it
 * and returns them to the Express error handler.
 *
 * @param fn The function that should be handled asynchronously
 */
export function asyncWrap(fn: RequestHandler) {
  return (request: Request, response: Response, next: NextFunction) => {
    return Promise.resolve(fn(request, response, next)).catch(next)
  }
}

/**
 * Adds a /metrics endpoint, register default runtime metrics and instrument the router.
 */
export function metricsHandler(): RequestHandler {
  // We can only initialize the metrics once and have to clean them up between hot reloads
  useHotCleanup(module, () => prom.register.clear());

  return promBundle({
    includeMethod: true,
    includePath: true,
    // Using includePath alone is problematic, as it will include path labels with high
    // cardinality (e.g. path params). Instead we would have to template them. However, this
    // is difficult, as every backend plugin might use different routes. Instead we only take
    // the first directory of the path, to have at least an idea how each plugin performs:
    normalizePath,
    promClient: { collectDefaultMetrics: {} },
  });
}

function hasRoleMiddleware(roleIds: readonly Role[], errorMessage: string): RequestHandler {
  return function (request, response, next) {
    const user = response.typedLocals.user as UserWithRoles | undefined;

    if (user == null) {
      return response.status(401).json({ error: errorMessage });
    }

    if (!isAdmin(user, request.method) && !hasRole(user, roleIds)) {
      return response.status(403).json({ error: errorMessage });
    }

    next();
  };
}

adapter = (httpPipeline: HttpPipeline): RequestHandler => {
  return (req, res, next) => {
    return httpPipeline.handle(req, res, {
      onLast: () => {
        next()
      },
    })
  }
}

/**
 * Check if the request has an up-to-date cached response by comparing the `If-None-Match` request header to the
 * current state. If the cache is valid then a `304 Not Modified` response is sent and the route handling for
 * this request is completed. If the cache is outdated, the current state is added to the `Request.locals` for
 * later use in setting response cache headers.
 * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Caching#freshness
 * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-None-Match
 * ```md
 * The If-None-Match HTTP request header makes the request conditional. For GET and HEAD methods, the server
 * will return the requested resource, with a 200 status, only if it doesn't have an ETag matching the given
 * ones. For other methods, the request will be processed only if the eventually existing resource's ETag
 * doesn't match any of the values listed.
 * ```
 */
export function getETagCacheHandler(
  db: DataStore,
  etagType: ETagType = ETagType.chainTip
): RequestHandler {
  const requestHandler = asyncHandler(async (req, res, next) => {
    const result = await checkETagCacheOK(db, req, etagType);
    if (result === CACHE_OK) {
      // Instruct the client to use the cached response via a `304 Not Modified` response header.
      // This completes the handling for this request, do not call `next()` in order to skip the
      // router handler used for non-cached responses.
      res.set('Cache-Control', CACHE_CONTROL_MUST_REVALIDATE).status(304).send();
    } else {
      // Request does not have a valid cache. Store the etag for later
      // use in setting response cache headers.
      const etag: ETag | undefined = result;
      res.locals[etagType] = etag;
      next();
    }
  });
  return requestHandler;
}

function cors(params: CorsParams): RequestHandler {
  const { baseOpts, anyOriginPathPrefixes, jwtOrigin } = params;
  const anyOriginOpts = { ...baseOpts, origin: true };
  const jwtOpts = { ...baseOpts, origin: jwtOrigin };
  const getCorsOpts = (req: Request) => {
    const { method, path, token } = req;
    const allowAny =
      anyOriginPathPrefixes.some((p) => path.startsWith(p)) ||
      (!token && method === "OPTIONS");
    if (allowAny) {
      return anyOriginOpts;
    } else if (!token) {
      return jwtOpts;
    }
    const allowedOrigins = token.access?.cors?.allowedOrigins ?? [];
    return allowedOrigins.includes("*")
      ? anyOriginOpts
      : {
          ...baseOpts,
          origin: allowedOrigins,
        };
  };

  return corsLib((req, callback) => callback(null, getCorsOpts(req)));
}

function validateRequest(validationSchema: ValidationSchema): RequestHandler {
  /**
   * In dev environments, as an alternative to token authentication,
   * you can pass the authentication middleware by having a user id in the body.
   * Inject the user id into the schema so that validation will not fail.
   */
  if (process.env.MODE === "dev") {
    validationSchema.body = {
      uid: joi.any(),
      ...(validationSchema.body ?? {}),
    };
  }

  const { validationErrorMessage } = validationSchema;
  const normalizedValidationSchema: ValidationSchema = _.omit(
    validationSchema,
    "validationErrorMessage"
  );

  return (req: MonkeyTypes.Request, _res: Response, next: NextFunction) => {
    _.each(
      normalizedValidationSchema,
      (schema: object, key: keyof ValidationSchema) => {
        const joiSchema = joi.object().keys(schema);

        const { error } = joiSchema.validate(req[key] ?? {});
        if (error) {
          const errorMessage = error.details[0].message;
          throw new MonkeyError(
            422,
            validationErrorMessage ??
              `${errorMessage} (${error.details[0]?.context?.value})`
          );
        }
      }
    );

    next();
  };
}

adaptMulter: RequestHandler = (req, res, next) => {
  const upload = multer().single('picture')
  upload(req, res, error => {
    if (error !== undefined) {
      return res.status(500).json({ error: new ServerError(error).message })
    }
    if (req.file !== undefined) {
      req.locals = { ...req.locals, file: { buffer: req.file.buffer, mimeType: req.file.mimetype } }
    }
    next()
  })
}

wrapExpressHandler = function (handler: RequestHandler): VercelApiHandler {
    return function (request: VercelRequest, response: VercelResponse): Promise<void> {
        return new Promise<void>(function (resolve, reject) {
            handler(request as any, response as any, function (error?: any) {
                if (error) {
                    reject(error);
                } else {
                    resolve();
                }
            });
        });
    };
}

wrapExpressHandler = function (handler: RequestHandler): NextApiHandler {
    return function (request: NextApiRequest, response: NextApiResponse): Promise<void> {
        return new Promise<void>(function (resolve, reject) {
            handler(request as any, response as any, function (error?: any) {
                if (error) {
                    reject(error);
                } else {
                    resolve();
                }
            });
        });
    };
}

authenticateSocketRequest = (
    io: Server,
    sessionMiddleware: RequestHandler,
    passport: PassportStatic
) => {
    const socketIoWrap = (middleware: any) => {
        return (
            socket: Socket,
            next: (err?: ExtendedError | undefined) => void
        ) => {
            return middleware(socket.request, {}, next);
        };
    };

    io.use(socketIoWrap(sessionMiddleware));
    io.use(socketIoWrap(passport.initialize()));
    io.use(socketIoWrap(passport.session()));

    io.use((socket, next) => {
        // @ts-ignore
        if (socket.request.user) {
            next();
        } else {
            next(new Error('unauthorized'));
        }
    });
}

setupMetaverseAPI: RequestHandler = async (req: Request, resp: Response, next: NextFunction) => {
  req.vRestResp = new RESTResponse(req, resp);
  if (req.socket) {
    req.vSenderKey = `${req.socket.remoteAddress}:${req.socket.remotePort}`;

    req.vSession = Sessions.getSessionWithSenderKey(req.vSenderKey);
    if (req.vSession) {
      Sessions.touchSession(req.vSession);
    }
    else {
      // No existing session for this request
      req.vSession = Sessions.createSession(req.vSenderKey);
      Sessions.addSession(req.vSession);
      Logger.debug('setupMetaverseAPI: created new session for ' + req.vSenderKey);
    };

    let authToken = req.vRestResp.getAuthToken();
    // If an authToken is not supplied in the header, it can be supplied in the query
    if (IsNullOrEmpty(authToken)) {
      if (req.query && req.query.access_token && typeof(req.query.access_token) === 'string') {
        authToken = (req.query.access_token as string);
      };
    };
    if (IsNotNullOrEmpty(authToken)) {
      try {
        req.vAuthToken = await Tokens.getTokenWithToken(authToken);
      }
      catch (err) {
        Logger.error(`setupMetaverseAPI: exception in token lookup: ${err}`);
      };
    };
  };
  next();
}

launchEditorMiddleware: RequestHandler = (req, res, next) => {
  if (req.url.startsWith(launchEditorEndpoint)) {
    /**
     * retain origin endpoint for backward compatibility <= v1.2.0
     */
    if (
      // relative route used in `Inspector.tsx` `gotoEditor()`
      req.url.startsWith(`${launchEditorEndpoint}/relative`)
      && typeof req.query.fileName === 'string'
    ) {
      req.query.fileName = path.join(process.cwd(), req.query.fileName)
    }

    reactLaunchEditorMiddleware(req, res, next)
  } else {
    next()
  }
}

/**
   * Serves the Purpose
   *
   * @returns {IRouter} - Router
   */
  serve(): IRouter {
    this.router.post('/get', (async (req, res) => {
      try {
        const leanHeader = req.headers['x-lean-doc-request'];
        const leanRequest = leanHeader ? true : false;
        const frontendDocs = await this.model.find({}).lean(leanRequest).exec();
        okResponse(res, frontendDocs);
      } catch (e) {
        errorResponseHandler(res, e);
      }
    }) as RequestHandler);

    this.router.delete('/reset', (async (req, res) => {
      try {
        const result = await this.model.clearAll();
        okResponse(res, result);
      } catch (e) {
        errorResponseHandler(res, e);
      }
    }) as RequestHandler);

    return this.router;
  }