nest.js - geting start

Installation

npm i -g @nestjs/cli

Create a new project

nest new project-name

Create a new module

nest g module module-name

Create a new controller

nest g controller controller-name

Create a new service

nest g service service-name

Create a new pipe

nest g pipe pipe-name

Create a new resource

nest g resource resource-name

Database

Nest.js is database agnostic, you can use any database you want. For example, you can use TypeORM, Sequelize, Mongoose, etc.

Install TypeORM with mysql driver

npm install --save @nestjs/typeorm typeorm mysql2

Troubleshooting

Error: Nest can’t resolve dependencies of the SearchHistoryService (?). Please make sure that the argument “SearchHistoryRepository” at index [0] is available in the SearchHistoryModule context.

1. 如果这个错误发生在一个module中（即不存在Module之间相互引用的情况），那么很可能是Module文件中缺少imports。加上下面这句：

import { Module } from '@nestjs/common';
import { SearchHistoryService } from './search_history.service';
import { SearchHistoryController } from './search_history.controller';
import { TypeOrmModule } from '@nestjs/typeorm';
import { SearchHistory } from './entities/search_history.entity';

@Module({
  imports: [TypeOrmModule.forFeature([SearchHistory])], // 这一句不能少！！！这个问题困扰了我一整天！
  controllers: [SearchHistoryController],
  providers: [SearchHistoryService],
})
export class SearchHistoryModule {}

2. 如果这个错误发生在module交叉引用中，比如A module中的service引用了B module的service，那么需
   要：

• 在B module中exports需要被引用的service
• 在A module中imports B module

// A module
imports: [BModule],

// B module
exports: [BService],

Database data was deleted after start nest.js

将app.module.ts中的synchronize设置为false，这样每次启动都不会删除数据。

@Module({
  imports: [
    TypeOrmModule.forRoot({
      type: 'xxx',
      host: 'xxx',
      port: 1234,
      username: 'xxx',
      password: 'xxx',
      database: 'xxx',
      entities: [xxx],
      logging: true,
      synchronize: false, // 这里设置为false！！！切记
    }),
    XXXModule,
  ],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}