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

Issue

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.

Solution

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 {}

Answered By - Micael Levi