Access a repo in a guard in nestjs

Question

Before upgrading to typeorm 0.3 I could use getConnection().getRepository<User>(User) in my guard to get a repo for a type and operate on it. With 0.3 however that is deprecated (see also https://newreleases.io/project/github/typeorm/typeorm/release/0.3.0) and now I cannot get access to the db in my guard anymore. I tried to use

 @InjectRepository(User)
 private userRepo: Repository<User>,

in the guard's constructor and then tried to make the guard a provider from a module that I exported but also that didnt work.

So I wonder how to get access to a repo or connection there. Otherwise I would probably need to pass my connection details to the Guard and create a new connecion ther which seems aweful.

Answer 1

You can try with mixin https://wanago.io/2021/12/13/api-nestjs-mixin-pattern/. Check the section Passing additional arguments.

I have done it with DataSource you can use Repository as well.

//scope.guard.ts
import { CanActivate, ExecutionContext, NotFoundException, Inject, Type, mixin } from "@nestjs/common";
import { DataSource, getRepository, ObjectType } from "typeorm";
import { Request } from "express";

const ScopeGuard = (entityClass): Type<CanActivate> => {
class ScopeGuardMixin {
constructor(@Inject(DataSource) private readonly dataSource: DataSource) {}

async canActivate(context: ExecutionContext): Promise<boolean> {
  console.log("here 1");
  console.log(entityClass);
  console.log("here 2");
  const request = context.switchToHttp().getRequest<Request>();
  console.log(await this.dataSource.getRepository(entityClass).findOneBy({ id: Number(request.params.id) }));
  return true;
}
}
return mixin(ScopeGuardMixin);
};
export default ScopeGuard;

Controller code

import ScopeGuard from "app/modules/guards/scope.guard";

@UseGuards(ScopeGuard(User))