将Nest.js应用程序作为简单的Express中间件导入-前端问题

Import a Nest.js app as a simple Express middleware(将Nest.js应用程序作为简单的Express中间件导入)

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问题描述

我有一个Nestjs应用程序(睡觉API)，我想将其作为简单的Express中间件(不是Nest中间件)导入到另一个节点模块中。实际上我还是不能使它工作。

// main.ts  
// => The main file of my Nest app, this one is working properly.

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  await app.listen(3000);
}
bootstrap();

// app.middleware.ts

import {Injectable, NestMiddleware} from '@nestjs/common';
import {NestFactory} from '@nestjs/core';
import {AppModule} from './app.module';
import {ExpressAdapter} from '@nestjs/platform-express';
import express, {Request, Response} from 'express';

const bootstrap = async () => {
  const expressApp = express();
  const adapter = new ExpressAdapter(expressApp);
  const app = await NestFactory.create(AppModule, adapter);
  await app.init();
  return app;
};

@Injectable()
export class AppMiddleware implements NestMiddleware {
  use(req: Request, res: Response, next: Function) {
    return bootstrap();
  }
}

// express-app.ts  
// => Here I'm trying to load my app through a simple Express middleware, but it doesn't works.

import express from 'express';
import { AppMiddleware } from './app.middleware';

const app = express();
const PORT = process.env.PORT || 3000;

app.use((req, res, next) => {
  const app = new AppMiddleware().use(req, res, next);
  app.then(next);
});

app.listen(PORT, () => {
  console.log(`app running on port ${PORT}`);
});

从main.ts运行我的应用程序时，它工作正常(所有路由都工作正常，我正在获取正确的数据)。但是，当我尝试通过express-app.ts运行应用程序时，所有路由似乎都在工作(它们显示在终端中)，但是在任何情况下，我都会收到以下错误，而不是返回JSON对象：

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="utf-8">
    <title>Error</title>
</head>

<body>
    <pre>[object Object]</pre>
</body>

</html>

嵌套组件版本：

- @nestjs/common: "^6.10.14"
- @nestjs/core: "^6.10.14"
- @nestjs/platform-express: "^6.10.14"
- express: "^4.16.4"

app.midleware.ts

import { Injectable, NestMiddleware } from '@nestjs/common';
import { NestFactory } from '@nestjs/core';
import { ExpressAdapter } from '@nestjs/platform-express';
import { AppModule } from './app.module';

const bootstrap = async (express: Express.Application) => {
  const app = await NestFactory.create(AppModule, new ExpressAdapter(express));
  await app.init();
  return app;
}

@Injectable()
export class AppMiddleware implements NestMiddleware {

  constructor(private expressInstance: Express.Application) {}

  use(req: any, res: any, next: () => void) {
    console.log('In Nest middleware');
    return bootstrap(this.expressInstance);
  }
}

app.control er.ts

import { Controller, Get } from '@nestjs/common';
import { AppService } from './app.service';

@Controller()
export class AppController {
  constructor(private readonly appService: AppService) {}

  @Get()
  getHello(): string {
    return this.appService.getHello();
  }
}

app.service.ts

import { Injectable } from '@nestjs/common';

@Injectable()
export class AppService {
  getHello(): string {
    return 'Hello World!';
  }
}

app.module e.ts

import { Module } from '@nestjs/common';
import { AppController } from './app.controller';
import { AppService } from './app.service';

@Module({
  imports: [],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}

server.ts

import * as express from 'express';

import { AppMiddleware } from './app.middleware';

const app = express();

app.use((req, res, next) => {
  const nest = new AppMiddleware(app).use(req, res, next);
  nest.then(() => {
    next();
  }).catch(err => {
    console.log(JSON.stringify(err));
    next();
  });
});

app.listen(3000, () => {
  console.log('Listening on port 3000');
});

生成命令

npm run build
# mapped to nest build

启动命令

node dist/server.js

测试命令

▶ curl http://localhost:3000
Hello World!

控制台日志

Listening on port 3000
In Nest middleware
[Nest] 24235   - 02/18/2020, 8:05:44 PM   [NestFactory] Starting Nest application...
[Nest] 24235   - 02/18/2020, 8:05:44 PM   [InstanceLoader] AppModule dependencies initialized +15ms
[Nest] 24235   - 02/18/2020, 8:05:44 PM   [RoutesResolver] AppController {