【NestJS】03 全局模块与生命周期解析

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import { Module } from '@nestjs/common'
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import { AaaService } from './aaa.service'
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@Module({
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  providers: [AaaService],
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  exports: [AaaService], // 导出AaaService，供其他模块使用
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})
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export class AaaModule {}

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import { Module } from '@nestjs/common'
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import { BbbService } from './bbb.service'
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import { AaaModule } from '../aaa/aaa.module' // 必须Import
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@Module({
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  imports: [AaaModule], // 引入AaaModule才能用AaaService
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  providers: [BbbService],
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})
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export class BbbModule {}

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import { Injectable } from '@nestjs/common'
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import { AaaService } from '../aaa/aaa.service'
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@Injectable()
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export class BbbService {
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  constructor(private readonly aaaService: AaaService) {} // 注入成功
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  doSomething() {
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    return this.aaaService.getInfo() // 使用AaaService的方法
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  }
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}

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import { Module, Global } from '@nestjs/common' // 引入Global装饰器
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import { AaaService } from './aaa.service'
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@Global() // 声明为全局模块
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@Module({
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  providers: [AaaService],
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  exports: [AaaService], // 依然需要导出，否则全局也拿不到
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})
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export class AaaModule {}

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import { Module } from '@nestjs/common'
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import { BbbService } from './bbb.service'
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@Module({
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  providers: [BbbService], // 不用Import AaaModule！
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})
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export class BbbModule {}

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import { Module, OnApplicationShutdown } from '@nestjs/common'
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import { TypeOrmModule, TypeOrmModuleOptions } from '@nestjs/typeorm'
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import { ModuleRef } from '@nestjs/core'
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import { Connection } from 'typeorm'
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@Module({
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  imports: [
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    TypeOrmModule.forRoot({
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      /* TypeORM配置 */
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    } as TypeOrmModuleOptions),
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  ],
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})
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export class DatabaseModule implements OnApplicationShutdown {
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  constructor(private moduleRef: ModuleRef) {}
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  onApplicationShutdown() {
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    const connection = this.moduleRef.get<Connection>(Connection) // 获取TypeORM连接
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    if (connection.isConnected) {
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      await connection.close() // 关闭连接
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      console.log('💾 TypeORM连接已关闭')
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    }
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  }
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}