Nest can't resolve dependencies of the AppModule (?) After set a middleware-CodePudding

I try to follow the documentation of nestjs middleware and I have a problem on my nest application after adding and set a middleware. I've seen the FAQ about the same common error from nestjs itself but still confused to solve this problem.

Error on my terminal

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

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

    at Injector.lookupComponentInParentModules (c:\codelab\nestlab\node_modules\@nestjs\core\injector\injector.js:230:19)
    at Injector.resolveComponentInstance (c:\codelab\nestlab\node_modules\@nestjs\core\injector\injector.js:184:33)
    at resolveParam (c:\codelab\nestlab\node_modules\@nestjs\core\injector\injector.js:106:38)
    at async Promise.all (index 0)
    at Injector.resolveConstructorParams (c:\codelab\nestlab\node_modules\@nestjs\core\injector\injector.js:121:27)
    at Injector.loadInstance (c:\codelab\nestlab\node_modules\@nestjs\core\injector\injector.js:52:9)
    at Injector.loadProvider (c:\codelab\nestlab\node_modules\@nestjs\core\injector\injector.js:74:9)
    at async Promise.all (index 0)
    at InstanceLoader.createInstancesOfProviders (c:\codelab\nestlab\node_modules\@nestjs\core\injector\instance-loader.js:44:9)
    at c:\codelab\nestlab\node_modules\@nestjs\core\injector\instance-loader.js:29:13

the problem is while I set AuthMiddleware on my AppModule constructor like this

  constructor(consumer: MiddlewareConsumer) {
    consumer
      .apply(AuthMiddleware)
      .forRoutes({
        path: '*',
        method: RequestMethod.GET,
      });
  }

and this my related code.

AuthMiddleware.ts

import { Injectable, NestMiddleware } from '@nestjs/common';

@Injectable()
export class AuthMiddleware implements NestMiddleware {
  use(req: any, res: any, next: () => void) {
    console.log('AuthMiddleware passed');
    next();
  }
}

app.module.ts

import { MiddlewareConsumer, Module, RequestMethod } from '@nestjs/common';
import { AppController } from './app.controller';
import { AppService } from './app.service';
import { AuthMiddleware } from './auth.middleware';

@Module({
  imports: [],
  controllers: [AppController],
  providers: [AppService],
})

export class AppModule {
  constructor(consumer: MiddlewareConsumer) {
    consumer
      .apply(AuthMiddleware)
      .forRoutes({
        path: '*',
        method: RequestMethod.GET,
      });
  }
}

Thanks for your attention & your help.

CodePudding user response：

the Object is provider means that you're injecting using an interface (the MiddlewareConsumer one)

If you read the docs on middleware consumer, you'll notice that the
consumer: MiddlewareConsumer parameter should be used in configure method, not in constructor

Also, do this to improve the type checking:

class AppModule implements NestModule {}