前言
nest是一款兼容typescript和javascript的node.js框架.本文使用nest的一些基本模块，来搭建一个简单的web后端CURD应用程序。typeORM是一款比较成熟的对象关系映射器，它是由typescript写的。nest和typeORM的具体介绍，可以查看官方文档。
项目搭建
使用CLI搭建project:
npm i -g @nestjs/cli nest new nest-app
这样就创建了一个nest-app项目，创建完成后，在src文件夹中包含以下几个核心文件：
src├── app.controller.ts├── app.module.ts└── main.ts
main.ts问项目启动文件，默认监听端口3000，根模块app.module.ts,路由实例app.controller.ts.
现在执行以下命令运行项目：
npm run start
启动后，在浏览器中输入localhost:3000,可以看到Hello world.
typeORM的使用
安装typeorm:
npm install --save @nestjs/typeorm typeorm mysql
typeorm支持多种数据库，本项目使用的是mysql。
创建实体employee和company,文件目录:
entities├── employee.entity.ts├── company.entity.ts
import { Entity, Column, PrimaryGeneratedColumn, ManyToOne, JoinTable } from ‘typeorm‘;import { Company } from ‘./company.entity‘@Entity()export class Employee { ???@PrimaryGeneratedColumn() ???id: number ???@Column() ???name: string ???@Column() ???age: number ???@Column() ???address: string ???@ManyToOne(type => Company, company => company.employees, { cascade: true }) ???@JoinTable() ???company: Company}company.entity.ts:
import { Entity, Column, PrimaryGeneratedColumn, OneToMany } from ‘typeorm‘;import { Employee } from ‘./employee.entity‘@Entity()export class Company { ???@PrimaryGeneratedColumn() ???id: number ???@Column() ???name: string ???@OneToMany(type => Employee, employee => employee.company) ???employees: Employee[]}在typeorm中都是通过装饰器来指定对象映射关系，本项目实体中目前主要使用仅使用了自增长主键，数据列，一对多关系等基本功能，在定义实体对象之间的关系时，关系一定要清楚，本例使用了cascade,可以用于级联删除级联保存操作。注意：级联删除和级联保存仅在save()时会生效，在insert()时无效。
创建employee模块
employee├── employee.controller.ts├── employee.module.ts└── employee.service.ts
employee.service.ts:
import { Injectable } from ‘@nestjs/common‘;import { Employee } from ‘../entities/employee.entity‘import { InjectRepository } from ‘@nestjs/typeorm‘;import { Repository } from ‘typeorm‘;import { Company } from ‘../entities/company.entity‘@Injectable()export class EmployeeService { ???constructor(@InjectRepository(Employee) ???private readonly employeeRepository: Repository<Employee>) { } ???root(): string { ???????return ‘Hello World!‘; ???} ???async create(): Promise<string> { ???????let employee = new Employee(); ???????let company = new Company(); ???????company.name = ‘asc‘; ???????employee.name = ‘novak‘; ???????employee.age = 20; ???????employee.address = ‘shanghai‘; ???????employee.company = company; ???????return this.employeeRepository.save(employee) ???????????.then(res => { ???????????????return ‘create employee ...done‘ ???????????}) ???????????.catch(err => { ???????????????return err ???????????}); ???} ???async findOne(name: string): Promise<Employee> { ???????return await this.employeeRepository.findOne({ name: name }); ???}}employee.controller.ts:
import { Get, Controller,Param } from ‘@nestjs/common‘;
import { EmployeeService } from ‘./employee.service‘;
import { Employee } from ‘entities/employee.entity‘;
@Controller(‘employee‘)
export class EmployeeController {
???constructor(private readonly employeeService: EmployeeService) {}
???@Get()
???root():string{
???????console.log(123)
???????return this.employeeService.root();
???}
???@Get(‘findOne/:name‘)
???async findOne(@Param() params):Promise<Employee>{
???????console.log(params.name);
???????return this.employeeService.findOne(params.name);
???}
???@Get(‘create‘)
???async create():Promise<string>{
???????console.log(‘1323‘)
???????return this.employeeService.create();
???}
}
employee.module.ts:
import { Module } from ‘@nestjs/common‘;import { TypeOrmModule } from ‘@nestjs/typeorm‘;import { EmployeeController } from ‘./employee.controller‘import { EmployeeService } from ‘./employee.service‘import { Employee } from ‘../entities/employee.entity‘@Module({ ???imports: [TypeOrmModule.forFeature([Employee])], ???providers: [EmployeeService], ???controllers: [EmployeeController]})export class EmployeeModule { ?}在employee.module.ts中TypeOrmModule.forFeature（）是用于动态获取模块对象。在employee.controller.ts使用了基本的路由配置方式。
模块注入，数据库连接信息配置
在根目录中注入employee模块：
import { Module } from ‘@nestjs/common‘;import { AppController } from ‘./app.controller‘;import { AppService } from ‘./app.service‘;import { TypeOrmModule } from ‘@nestjs/typeorm‘;import {EmployeeModule} from ‘./employee/employee.module‘@Module({ ?imports: [ ???TypeOrmModule.forRoot(), ???EmployeeModule ?], ?controllers: [AppController], ?providers: [AppService],})export class AppModule { }可以看到，在imports中使用typeormmodule.forRoot()用于动态返回typeormmodule，typeormmodule连接数据库的方式有多种，可以使用配置文件，也可以在forRoot()中传入options参数信息，本例使用配置文件，在src目录下添加ormconfig.json文件：
{ ???"type": "mysql", ???"host": "localhost", ???"port": 3306, ???"username": "root", ???"password": "root", ???"database": "nest-app", ???"entities": ["src/**/**.entity{.ts,.js}"], ???"synchronize": true ?}至此一个基本的带有employee的创建和查询功能的service程序已搭建完毕，浏览器输入：localhost:3000/employee/create看看效果吧。
源码github
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nest.js + typeORM:基本使用
原文地址：https://www.cnblogs.com/novak12/p/9249688.html