I want to create an instance of this class which has arguments in its constructor as follows? - constructor

Question

export class AuthService {
constructor(
private readonly usersService: UsersService,
#InjectModel('User') private readonly userModel: PassportLocalModel<IUser>,
) {}
async register(user: CreateUserDto) {
let status: RegistrationStatus = {
success: true,
message: 'user registerd',
};
await this.userModel.register(
new this.userModel({
username: user.email,
firstName: user.firstName,
lastName: user.lastName,
}),
user.password,
err => {
if (err) {
console.log(err);
status = { success: false, message: err };
}
},
);
return status;
}
}
I want to create an instance of this class but I am not able to figure out how to pass the arguments. How to handle the arguments for passport local model containing Iuser?

Answer 1

Looks like you lack on comprehension of the Dependency Injection of NestJS.
You should never instantiate a Service, but import it in the constructor of other class in the same way you are doing it with the UsersService.
For example, having your AuthServiceannotated with #Service decorator:
#Service
export class AuthService { ... }
You can then use it, let's say, in your AuthController
#Controller()
export class AuthController{
constructor (private readonly authService: AuthService) {}
register(user: UserDTO): RegistrationStatus {
this.authService.register(user);
}
}
NestJS will handle the instantiation of the Service and all its dependencies.
Just remember to add the AuthService in the providers property of the AuthModule, and, if you are going to use outside this module, export it adding it to the exports property.
Is a good practice to specify return types in methods.