Loopback 4中间件未注册

如何解决Loopback 4中间件未注册

我正在遵循此example here进行简单的日志记录中间件设置。但是我似乎无法获取它来记录我的请求信息。当我按下/ping时，我得到标准响应，但是没有任何内容注销到控制台。

我尝试在两个不同的位置注册中间件。 index.ts和application.ts。

// src/middleware/log.middleware.ts

import { Next } from '@loopback/core'
import { Middleware,MiddlewareContext } from '@loopback/rest'

export const testLoggingMiddleware: Middleware = async (
  middlewareCtx: MiddlewareContext,next: Next,) => {
  const { request } = middlewareCtx
  console.log('Request: %s %s',request.method,request.originalUrl)
  try {
    // Proceed with next middleware
    await next()
    // Process response
    console.log('Response received for %s %s',request.originalUrl)
  } catch (err) {
    // Catch errors from downstream middleware
    console.error('Error received for %s %s',request.originalUrl)
    throw err
  }
}

// src/index.ts

import { ApplicationConfig,RemoteConfigurationsApplication } from './application'
import { testLoggingMiddleware } from './middleware/log.middleware'
import { NodeEnvironmentService } from './services'

export * from './application'

export async function main(
  options: ApplicationConfig = {},): Promise<RemoteConfigurationsApplication> {
  const app = new RemoteConfigurationsApplication(options)

  app.middleware(testLoggingMiddleware) // trying to add the middleware here as well

  await app.boot()
  await app.start()

  const url = app.restServer.url
  console.log(`Server is running at ${url}`)
  console.log(`Try ${url}/ping`)

  return app
}

if (require.main === module) {
  // Run the application
  const config = {
    rest: {
      port: +(process.env.PORT ?? 8081),host: process.env.HOST,// The `gracePeriodForClose` provides a graceful close for http/https
      // servers with keep-alive clients. The default value is `Infinity`
      // (don't force-close). If you want to immediately destroy all sockets
      // upon stop,set its value to `0`.
      // See https://www.npmjs.com/package/stoppable
      gracePeriodForClose: 5000,// 5 seconds
      openApiSpec: {
        // useful when used with OpenAPI-to-GraphQL to locate your application
        setServersFromRequest: true,},basePath: `/`,cors: {
        origin: '*',methods: 'GET,HEAD,PUT,PATCH,POST,DELETE',preflightContinue: false,optionsSuccessStatus: 204,credentials: true,}
  main(config).catch((err) => {
    console.error('Cannot start the application.',err)
    process.exit(1)
  })
}

// src/application.ts

require('dotenv').config()

import { BootMixin } from '@loopback/boot'
import { ApplicationConfig } from '@loopback/core'
import { HealthComponent } from '@loopback/extension-health'
import { RestExplorerBindings,RestExplorerComponent } from '@loopback/rest-explorer'
import { RepositoryMixin } from '@loopback/repository'
import { RestApplication } from '@loopback/rest'
import { ServiceMixin } from '@loopback/service-proxy'
import * as path from 'path'
import { testLoggingMiddleware } from './middleware/log.middleware'
import { MySequence } from './sequence'

export { ApplicationConfig }

export class RemoteConfigurationsApplication extends BootMixin(
  ServiceMixin(RepositoryMixin(RestApplication)),) {
  constructor(options: ApplicationConfig = {}) {
    super(options)

    // Set up the custom sequence
    this.sequence(MySequence)

    // Set up default home page
    this.static('/',path.join(__dirname,'../public'))

    // Customize @loopback/http-explorer configuration here
    this.configure(RestExplorerBindings.COMPONENT).to({
      path: '/explorer',})
    this.component(RestExplorerComponent)

    this.component(HealthComponent)

    this.middleware(testLoggingMiddleware) // adding middleware in application

    this.projectRoot = __dirname
    // Customize @loopback/boot Booter Conventions here
    this.bootOptions = {
      controllers: {
        // Customize ControllerBooter Conventions here
        dirs: ['controllers'],extensions: ['.controller.js'],nested: true,}
  }
}

解决方法

使用您的中间件，我可以在控制台上看到日志，按照 @Varun 建议将 MySequence 类替换为以下代码后，您可以获得更多详细信息 here

import { MiddlewareSequence } from '@loopback/rest';

export class MySequence extends MiddlewareSequence {}

为了能够向客户端发送响应，您需要从中间件返回 await next()

export const testLoggingMiddleware: Middleware = async (
  middlewareCtx: MiddlewareContext,next: Next,) => {
  const {request} = middlewareCtx
  console.log('Request: %s %s',request.headers,request.method,request.originalUrl)
  try {
    // Proceed with next middleware
    const result = await next()
    // Process response
    console.log('Response received for %s %s',request.originalUrl)
    return result
  } catch (err) {
    // Catch errors from downstream middleware
    console.error('Error received for %s %s',request.originalUrl)
    throw err
  }
}

如果有人仍然遇到这个问题，这对我有用：

更新您的 sequence.ts 使其看起来像这样：

    import { MiddlewareSequence } from '@loopback/rest';
    
    export class MySequence extends MiddlewareSequence {}

在 /src/middleware/example.middleware.ts 上创建中间件


import { Next } from '@loopback/core'
import { Middleware,MiddlewareContext } from '@loopback/rest'

export const exampleMiddleware: Middleware = async (
  middlewareCtx: MiddlewareContext,request.originalUrl)
    throw err
  }
}

在 application.ts 中注册您的中间件

    import {ApplicationConfig} from '@loopback/core';
    import {RestApplication} from '@loopback/rest';
    import {exampleMiddleware} from './middleware/example.middleware';

    export class MyApplication extends RestApplication {
      constructor(config: ApplicationConfig) {
        // register your middleware
        this.middleware(exampleMiddleware);
      }
    }

运行应用并检查您的控制台。

Reference doc

如@Rifa所述，您需要更新MySequence类

之前，它具有以下内容-

import { inject } from '@loopback/context';
import {
  FindRoute,InvokeMethod,ParseParams,Reject,RequestContext,RestBindings,Send,SequenceHandler,InvokeMiddleware
} from '@loopback/rest';

const SequenceActions = RestBindings.SequenceActions;

export class MySequence implements SequenceHandler {
  /**
   * Optional invoker for registered middleware in a chain.
   * To be injected via SequenceActions.INVOKE_MIDDLEWARE.
   */
  @inject(SequenceActions.INVOKE_MIDDLEWARE,{ optional: true })
  protected invokeMiddleware: InvokeMiddleware = () => false;

  constructor(
    @inject(SequenceActions.FIND_ROUTE) protected findRoute: FindRoute,@inject(SequenceActions.PARSE_PARAMS) protected parseParams: ParseParams,@inject(SequenceActions.INVOKE_METHOD) protected invoke: InvokeMethod,@inject(SequenceActions.SEND) public send: Send,@inject(SequenceActions.REJECT) public reject: Reject
  ) {}

  async handle(context: RequestContext) {
    try {
      const { request,response } = context;
      // Invoke registered Express middleware
      const finished = await this.invokeMiddleware(context);
      if (finished) {
        // The response been produced by the middleware chain
        return;
      }
      const route = this.findRoute(request);
      const args = await this.parseParams(request,route);
      const result = await this.invoke(route,args);
      this.send(response,result);
    } catch (err) {
      this.reject(context,err);
    }
  }
}

替换为-

import { MiddlewareSequence } from '@loopback/rest';

export class MySequence extends MiddlewareSequence {}

Loopback 4中间件未注册

如何解决Loopback 4中间件未注册

解决方法

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