NestJS无法在AuthGuard中注入服务问题求助

尝试在JwtAccessTokenGuard中注入JwtTokenService时触发依赖解析错误，相关代码及报错信息如下：

守卫代码 #

@Injectable()
export class JwtAccessTokenGuard implements CanActivate {
  constructor(
    @Inject(JwtTokenService) private readonly jwtTokenService: JwtTokenService,
  ) {}

  async canActivate(context: ExecutionContext): Promise<boolean> {
    const request = context.switchToHttp().getRequest();
    const token = this.extractTokenFromHeader(request);
    if (!token) throw new UnauthorizedException();
    try {
      return true;
    } catch {
      throw new UnauthorizedException();
    }
  }

  private extractTokenFromHeader(request: Request): string | undefined {
    const [type, token] = request.headers.authorization?.split(' ') ?? [];
    return type === 'Bearer' ? token : undefined;
  }
}

AppModule全局守卫配置 #

@Module({
  imports: [
    ConfigModule.forRoot({ isGlobal: true }),
    AuthModule,
    UserModule,
    PrismaModule,
    BcryptModule,
    JwtTokenModule,
    LibModule,
    TwoFaModule,
  ],
  providers: [
    {
      provide: APP_GUARD,
      useClass: JwtAccessTokenGuard,
    },
  ],
})
export class AppModule {}

UserModule代码 #

@Module({
  controllers: [UserController, JwtTokenModule],
  providers: [UserService, PrismaService],
  exports: [UserService],
})
export class UserModule {}

JwtTokenModule代码 #

import { Module } from '@nestjs/common';
import { JwtTokenService } from './jwtToken.service';
import { JwtModule } from '@nestjs/jwt';

@Module({
  imports: [JwtModule],
  providers: [JwtTokenService],
  exports: [JwtTokenService],
})
export class JwtTokenModule {}

报错信息 #

[Nest] 79549  - 09/28/2023, 12:35:42 AM   ERROR [ExceptionHandler] Nest can't resolve dependencies of the JwtAccessTokenGuard (?). Please make sure that the argument JwtTokenService at index [0] is available in the UserModule context.

Potential solutions:
- Is UserModule a valid NestJS module?
- If JwtTokenService is a provider, is it part of the current UserModule?
- If JwtTokenService is exported from a separate @Module, is that module imported within UserModule?
  @Module({
    imports: [ /* the Module containing JwtTokenService */ ]
  })

Error: Nest can't resolve dependencies of the JwtAccessTokenGuard (?). Please make sure that the argument JwtTokenService at index [0] is available in the UserModule context.

1. 修复UserModule的错误配置 #

UserModule中错误地将JwtTokenModule放在了controllers数组里，这是核心问题。全局守卫作用于UserModule的路由时，Nest会检查UserModule上下文是否能提供守卫的依赖，因此需要将JwtTokenModule移到imports数组中：

@Module({
  controllers: [UserController],
  imports: [JwtTokenModule], // 修正：将JwtTokenModule移到这里
  providers: [UserService, PrismaService],
  exports: [UserService],
})
export class UserModule {}

2. 简化守卫的注入写法 #

@Inject(JwtTokenService)是多余的，Nest默认会以类作为注入令牌，直接简化构造函数即可：

constructor(private readonly jwtTokenService: JwtTokenService) {}

3. （可选）优化全局守卫的组织方式 #

如果项目规模较大，建议将JwtAccessTokenGuard放到单独的AuthModule中，并在AuthModule中导入JwtTokenModule，然后在AppModule中导入AuthModule。这样依赖关系更清晰，避免其他模块重复导入依赖：

// AuthModule示例
@Module({
  imports: [JwtTokenModule],
  providers: [
    JwtAccessTokenGuard,
    {
      provide: APP_GUARD,
      useClass: JwtAccessTokenGuard,
    },
  ],
})
export class AuthModule {}

内容的提问来源于stack exchange，提问作者user16715270