使用NestJS开发Node.js应用的方法

import { Module } from '@nestjs/common';
import { CatsController } from './cats.controller';
import { CatsService } from './cats.service';
import { OtherModule } from '../OtherModule';

@Module({
 imports: [OtherModule],
 controllers: [CatsController],
 providers: [CatsService],
})
export class CatsModule {}

// 创建一个服务
@Inject()
export class TestService {
 public find() {
 return 'hello world';
 }
}

// 创建一个 controller
@Controller()
export class TestController {
 controller(
 private readonly testService: TestService
 ) {}
 
 @Get()
 public findInfo() {
 return this.testService.find()
 }
}

@Module({
 controllers: [TestController],
 providers: [TestService],
})
export class TestModule {}

@Catch()
export class AllExceptionsFilter implements ExceptionFilter {
 catch(exception: any, host: ArgumentsHost) {
 const ctx = host.switchToHttp();
 const response = ctx.getResponse();
 const request = ctx.getRequest();
 const status = exception.getStatus();

 // 一些其他做的事情，如使用日志

 response
  .status(status)
  .json({
  statusCode: status,
  timestamp: new Date().toISOString(),
  path: request.url,
  });
 }
}

import { Injectable, NestInterceptor, ExecutionContext } from '@nestjs/common';
import { Observable } from 'rxjs';
import { map } from 'rxjs/operators';

export interface Response<T> {
 data: T;
}

@Injectable()
export class TransformInterceptor<T>
 implements NestInterceptor<T, Response<T>> {
 intercept(
 context: ExecutionContext,
 call$: Observable<T>,
 ): Observable<Response<T>> {
 return call$.pipe(map(data => ({ data })));
 }
}

import { ReflectMetadata } from '@nestjs/common';
export const Roles = (...roles: string[]) => ReflectMetadata('roles', roles);

@Post()
@Roles('admin')
async create(@Body() createCatDto: CreateCatDto) {
 this.catsService.create(createCatDto);
}

// 创建 Dto
export class ContentDto {
 @IsString()
 text: string
}

@Controller()
export class TestController {
 controller(
 private readonly testService: TestService
 ) {}
 
 @Get()
 public findInfo(
 @Param() param: ContentDto  // 使用
 ) {
 return this.testService.find()
 }
}

const express = require('express');
const { ApolloServer, gql } = require('apollo-server-express');

// Construct a schema, using GraphQL schema language
const typeDefs = gql`
 type Query {
 hello: String
 }
`;

// Provide resolver functions for your schema fields
const resolvers = {
 Query: {
 hello: () => 'Hello world!',
 },
};

const server = new ApolloServer({ typeDefs, resolvers });

const app = express();
server.applyMiddleware({ app });

const port = 4000;

app.listen({ port }, () =>
 console.log(`Server ready at http://localhost:${port}${server.graphqlPath}`),
);

// test.graphql
type Query {
 hello: string;
}


// test.resolver.ts
@Resolver()
export class {
 @Query()
 public hello() {
 return 'Hello wolrd';
 }
}