问题 nestjs - Nest 无法解析 AuthenticationService 的依赖项（？）

Question

The application stops immediately at startup, other modules have not been checked yet, so the error is unlikely in them.

authentication.service.ts

import { HttpException, HttpStatus, Inject, Injectable } from '@nestjs/common';
import { CreateUserDto } from 'src/users/dto/createUser.dto';
import { UserService } from 'src/users/user/user.service';
import bcrypt from 'bcrypt';

@Injectable()
export class AuthenticationService {
    constructor(@Inject() private readonly userService: UserService){}
    public async regiser(registartionData:CreateUserDto){
    const hashingPassword = await bcrypt.hash(registartionData.passwordHash, 10);
    try{
        const createUser = await this.userService.create({
            ...registartionData,
            passwordHash: hashingPassword
        })
        createUser.passwordHash = undefined;
        return createUser;
    }
    catch(err){
        throw new HttpException('Something went wrong', HttpStatus.INTERNAL_SERVER_ERROR);
    }
}
public async getAuthenticationUser(email:string, textPassword:string){
    try{
        const user = await this.userService.findByEmail(email);
        await this.verifyPassword(textPassword,user.passwordHash);
        user.passwordHash = undefined;
        return user;
    }
    catch(err){
        throw new HttpException('Wrong credentials provided', HttpStatus.BAD_REQUEST);
    }
}
private async verifyPassword(password:string, hashingPassword:string){
    const isMatching = await bcrypt.compare(password, hashingPassword);
    if(!isMatching) throw new HttpException('Wrong credentials provided', HttpStatus.BAD_REQUEST);
}
}

auth.module.ts

import { Module } from '@nestjs/common';
import { PassportModule } from '@nestjs/passport';
import { UsersModule } from 'src/users/users.module';
import { AuthController } from '../controllers/auth/auth.controller';
import { AuthenticationService } from './authentication/authentication.service';
import { LocalStrategy } from './authentication/local.strategy';

@Module({
  imports:[UsersModule, PassportModule, ],
  providers: [AuthenticationService, LocalStrategy],
  controllers:[AuthController],
  exports: [AuthenticationService]
})
export class AuthModule {}

this error

 Nest can't resolve dependencies of the AuthenticationService (?). Please make sure that the argument dependency at index [0] is available in the AuthModule context.

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

I don't understand error, export and provide auth service. I don't use auth service in other modules.

Answer 1

All my services use the mongodb model. Therefore, you need to do the following in modules and services.

user.module.ts

@Module({
*imports: [MongooseModule.forFeature([{ name: 'User', schema: UserSchema }])],*
  providers: [UserService],
  exports: [UserService],
})
export class UsersModule {}

user.service.ts

@Injectable()
export class UserService implements IUserService {
  constructor(
*@InjectModel(User.name) private userModel: Model<User>*
) {}

good example https://wanago.io/2021/08/23/api-nestjs-relationships-mongodb/

Answer 2

The code in yours repo cannot be even compiled, so cannot help you almost at all. There are lack of things, ts-errors etc.

but from what i see:

• UsersModule has provider UserService but its not exporting it. Therefore NO OTHER MODULE would have access to it. You need to export the UserService too.
• AuthModule do not imports UserService (and nothing exports it) so its not found at the time of Nest trying to match injects. What you can do is to add imports: [UserModule] in AuthModule (and also export UserService in UserModule).

And read again the documentation of modules and example project to see how imports, exports, controllers and providers works.